1
|
Herrera-Pérez JJ, Hernández-Hernández OT, Flores-Ramos M, Cueto-Escobedo J, Rodríguez-Landa JF, Martínez-Mota L. The intersection between menopause and depression: overview of research using animal models. Front Psychiatry 2024; 15:1408878. [PMID: 39081530 PMCID: PMC11287658 DOI: 10.3389/fpsyt.2024.1408878] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2024] [Accepted: 06/28/2024] [Indexed: 08/02/2024] Open
Abstract
Menopausal women may experience symptoms of depression, sometimes even progressing clinical depression requiring treatment to improve quality of life. While varying levels of estrogen in perimenopause may contribute to an increased biological vulnerability to mood disturbances, the effectiveness of estrogen replacement therapy (ERT) in the relief of depressive symptoms remains controversial. Menopausal depression has a complex, multifactorial etiology, that has limited the identification of optimal treatment strategies for the management of this psychiatric complaint. Nevertheless, clinical evidence increasingly supports the notion that estrogen exerts neuroprotective effects on brain structures related to mood regulation. Indeed, research using preclinical animal models continues to improve our understanding of menopause and the effectiveness of ERT and other substances at treating depression-like behaviors. However, questions regarding the efficacy of ERT in perimenopause have been raised. These questions may be answered by further investigation using specific animal models of reduced ovarian function. This review compares and discusses the advantages and pitfalls of different models emulating the menopausal stages and their relationship with the onset of depressive-like signs, as well as the efficacy and mechanisms of conventional and novel ERTs in treating depressive-like behavior. Ovariectomized young rats, middle-to-old aged intact rats, and females treated with reprotoxics have all been used as models of menopause, with stages ranging from surgical menopause to perimenopause. Additionally, this manuscript discusses the impact of organistic and therapeutic variables that may improve or reduce the antidepressant response of females to ERT. Findings from these models have revealed the complexity of the dynamic changes occurring in brain function during menopausal transition, reinforcing the idea that the best approach is timely intervention considering the opportunity window, in addition to the careful selection of treatment according to the presence or absence of reproductive tissue. Additionally, data from animal models has yielded evidence to support new promising estrogens that could be considered as ERTs with antidepressant properties and actions in endocrine situations in which traditional ERTs are not effective.
Collapse
Affiliation(s)
- José Jaime Herrera-Pérez
- Laboratorio de Farmacología Conductual, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City, Mexico
| | - Olivia Tania Hernández-Hernández
- Consejo Nacional de Humanidades, Ciencias y Tecnologías Research Fellow. Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City, Mexico
| | - Mónica Flores-Ramos
- Subdirección de Investigaciones Clínicas, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City, Mexico
| | - Jonathan Cueto-Escobedo
- Departamento de Investigación Clínica, Instituto de Ciencias de la Salud, Universidad Veracruzana, Xalapa-Enríquez, Mexico
| | | | - Lucía Martínez-Mota
- Laboratorio de Farmacología Conductual, Dirección de Investigaciones en Neurociencias, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City, Mexico
| |
Collapse
|
2
|
Caputo R, Poirel VJ, Challet E, Meijer JH, Raison S. Bimodal serotonin synthesis in the diurnal rodent, Arvicanthis ansorgei. FASEB J 2022; 36:e22255. [PMID: 35294080 DOI: 10.1096/fj.202101726r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 02/05/2022] [Accepted: 03/04/2022] [Indexed: 11/11/2022]
Abstract
In mammals, behavioral activity is regulated both by the circadian system, orchestrated by the suprachiasmatic nucleus (SCN), and by arousal structures, including the serotonergic system. While the SCN is active at the same astronomical time in diurnal and nocturnal species, little data are available concerning the serotonergic (5HT) system in diurnal mammals. In this study, we investigated the functioning of the 5HT system, which is involved both in regulating the sleep/wake cycle and in synchronizing the SCN, in a diurnal rodent, Arvicanthis ansorgei. Using in situ hybridization, we characterized the anatomical extension of the raphe nuclei and we investigated 24 h mRNA levels of the serotonin rate-limiting enzyme, tryptophan hydroxylase 2 (tph2). Under both 12 h:12 h light/dark (LD) and constant darkness (DD) conditions, tph2 mRNA expression varies significantly over 24 h, displaying a bimodal profile with higher values around the (projected) light transitions. Furthermore, we considered several SCN outputs, namely melatonin, corticosterone, and locomotor activity. In both LD and DD, melatonin profiles display peak levels during the biological night. Corticosterone plasma levels show a bimodal rhythmic profile in both conditions, with higher levels preceding the two peaks of Arvicanthis locomotor activity, occurring at dawn and dusk. These data demonstrate that serotonin synthesis in Arvicanthis is rhythmic and reflects its bimodal behavioral phenotype, but differs from what has been previously described in nocturnal species.
Collapse
Affiliation(s)
- Rosanna Caputo
- Institute of Cellular and Integrative Neurosciences, CNRS and University of Strasbourg, Strasbourg, France.,Department of Molecular Cell Biology, Division of Neurophysiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Vincent-Joseph Poirel
- Institute of Cellular and Integrative Neurosciences, CNRS and University of Strasbourg, Strasbourg, France
| | - Etienne Challet
- Institute of Cellular and Integrative Neurosciences, CNRS and University of Strasbourg, Strasbourg, France
| | - Johanna H Meijer
- Department of Molecular Cell Biology, Division of Neurophysiology, Leiden University Medical Center, Leiden, the Netherlands
| | - Sylvie Raison
- Institute of Cellular and Integrative Neurosciences, CNRS and University of Strasbourg, Strasbourg, France
| |
Collapse
|
3
|
McDevitt RA, Marino RAM, Tejeda HA, Bonci A. Serotonergic inhibition of responding for conditioned but not primary reinforcers. Pharmacol Biochem Behav 2021; 205:173186. [PMID: 33836219 DOI: 10.1016/j.pbb.2021.173186] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 02/19/2021] [Accepted: 03/29/2021] [Indexed: 10/21/2022]
Abstract
Serotonin is widely implicated as a modulator of brain reward function. However, laboratory studies have not yielded a consensus on which specific reward-related processes are influenced by serotonin and in what manner. Here we explored the role of serotonin in cue-reward learning in mice. In a first series of experiments, we found that acute administration of the serotonin reuptake inhibitors citalopram, fluoxetine, or duloxetine all reduced lever pressing reinforced on an FR1 schedule with presentation of a cue that had been previously paired with delivery of food. However, citalopram had no effect on responding that was reinforced with both cue and food on an FR1 schedule. Furthermore, citalopram did not affect nose poke responses that produced no auditory, visual, or proprioceptive cues but were reinforced with food pellets on a progressive ratio schedule. We next performed region-specific knock out of tryptophan hydroxylase-2 (Tph2), the rate-limiting enzyme in serotonin synthesis. Viral delivery of Cre recombinase was targeted to dorsal or median raphe nuclei (DRN, MRN), the major sources of ascending serotonergic projections. MRN but not DRN knockouts were impaired in development of cue-elicited approach during Pavlovian conditioning; both groups were subsequently hyper-responsive when lever pressing for cue presentation. The inhibitory effect of citalopram was attenuated in DRN but not MRN knockouts. Our findings are in agreement with prior studies showing serotonin to suppress responding for conditioned reinforcers. Furthermore, these results suggest an inhibitory role of MRN serotonin neurons in the initial attribution of motivational properties to a reward-predictive cue, but not in its subsequent maintenance. In contrast, the DRN appears to promote the reduction of motivational value attached to a cue when it is presented repeatedly in the absence of primary reward.
Collapse
Affiliation(s)
- Ross A McDevitt
- Synaptic Plasticity Section, National Institute on Drug Abuse, Baltimore, MD, United States of America; Comparative Medicine Section, National Institute on Aging, Baltimore, MD, United States of America.
| | - Rosa Anna M Marino
- Synaptic Plasticity Section, National Institute on Drug Abuse, Baltimore, MD, United States of America; Department of Anatomy and Neurobiology, University of Maryland School of Medicine, Baltimore, MD, United States of America
| | - Hugo A Tejeda
- Synaptic Plasticity Section, National Institute on Drug Abuse, Baltimore, MD, United States of America; Neuromodulation and Synaptic Integration Unit, National Institute on Mental Health, Bethesda, MD, United States of America
| | - Antonello Bonci
- Global Institutes on Addictions, Miami, FL, United States of America
| |
Collapse
|
4
|
Sepulveda M, Manning EE, Gogos A, Hale M, van den Buuse M. Long-term effects of young-adult methamphetamine on dorsal raphe serotonin systems in mice: Role of brain-derived neurotrophic factor. Brain Res 2021; 1762:147428. [PMID: 33737066 DOI: 10.1016/j.brainres.2021.147428] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 02/15/2021] [Accepted: 03/08/2021] [Indexed: 01/21/2023]
Abstract
To assess the long-term effects of chronic adolescent methamphetamine (METH) treatment on the serotonin system in the brain, we used serotonin-1A receptor (5-HT1A) and serotonin transporter (SERT) autoradiography, and quantitative tryptophan-hydroxylase 2 (TPH2) immunohistochemistry in the raphe nuclei of mice. Because of the modulatory role of brain-derived neurotrophic factor (BDNF) on the serotonin system and the effects of METH, we included both BDNF heterozygous (HET) mice and wildtype (WT) controls. Male and female mice of both genotypes were treated with an escalating METH dose regimen from the age of 6-9 weeks. At least two weeks later, acute locomotor hyperactivity induced by a 5 mg/kg D-amphetamine challenge was significantly enhanced in METH-pretreated mice, showing long-term sensitisation. METH pretreatment caused a small, but significant decrease of 5-HT1A receptor binding in the dorsal raphe nucleus (DRN) of males independent of genotype, but there were no changes in the median raphe nucleus (MRN) or in SERT binding density. METH treatment reduced the number of TPH2 positive cells in ventral subregions of the rostral and medial DRN independent of genotype. METH treatment selectively reduced DRN cell counts in BDNF HET mice compared to wildtype mice in medial and caudal ventrolateral subregions previously associated with panic-like behaviour. The data increase our understanding of the long-term and selective effects of METH on brain serotonin systems. These findings could be relevant for some of the psychosis-like symptoms associated with long-term METH use.
Collapse
Affiliation(s)
- Mauricio Sepulveda
- Florey Institute for Neuroscience and Mental Health, University of Melbourne, Australia
| | - Elizabeth E Manning
- Florey Institute for Neuroscience and Mental Health, University of Melbourne, Australia
| | - Andrea Gogos
- Florey Institute for Neuroscience and Mental Health, University of Melbourne, Australia
| | - Matthew Hale
- School of Psychology and Public Health, La Trobe University, Melbourne, Australia
| | - Maarten van den Buuse
- School of Psychology and Public Health, La Trobe University, Melbourne, Australia; Department of Pharmacology, University of Melbourne, Australia; College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Australia.
| |
Collapse
|
5
|
Haleem DJ. Targeting Serotonin1A Receptors for Treating Chronic Pain and Depression. Curr Neuropharmacol 2020; 17:1098-1108. [PMID: 31418663 PMCID: PMC7057205 DOI: 10.2174/1570159x17666190811161807] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 07/31/2019] [Accepted: 08/02/2019] [Indexed: 02/07/2023] Open
Abstract
The association of chronic pain with depression is becoming increasingly recognized. Treating both the conditions together is essential for an effective treatment outcome. In this regard, it is important to identify a shared mechanism involved in the association of chronic pain with depression. Central serotonin (5-hydroxytryptamine; 5-HT) neurotransmission has long been known to participate in the processing of signals related to pain. It also plays a key role in the pathogenesis and treatment of depression. Although functional responses to serotonin are mediated via the activation of multiple receptor types and subtypes, the 5-HT1A subtype is involved in the processing of nociception as well as the pathogenesis and treatment of depression. This receptor is located presynaptically, as an autoreceptor, on the perikaryon and dendritic spines of serotonin-containing neurons. It is also expressed as a heteroreceptor on neurons receiving input from serotonergic neurons. This arti-cle targets the 5-HT1A receptors to show that indiscriminate activation of pre and postsynaptic 5-HT1A receptors is likely to produce no therapeutic benefits; biased activation of the 5-HT heteroreceptors may be a useful strategy for treating chronic pain and depression individually as well as in a comorbid condition.
Collapse
Affiliation(s)
- Darakhshan Jabeen Haleem
- Neuroscience Research Laboratory, Dr. Panjwani Center for Molecular Medicine & Drug Research (PCMD), International Center for Chemical and Biological Science (ICCBS), University of Karachi, Karachi 75270, Pakistan
| |
Collapse
|
6
|
Moriya S, Yamashita A, Masukawa D, Kambe Y, Sakaguchi J, Setoyama H, Yamanaka A, Kuwaki T. Involvement of supralemniscal nucleus (B9) 5-HT neuronal system in nociceptive processing: a fiber photometry study. Mol Brain 2020; 13:14. [PMID: 32005128 PMCID: PMC6993514 DOI: 10.1186/s13041-020-0553-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2019] [Accepted: 01/19/2020] [Indexed: 12/15/2022] Open
Abstract
Nociception is important perception that has harmful influence on daily life of humans. As to main pain management system, some descending pathways are called descending antinociceptive systems (DAS). As main pathways of DAS, it is well known that dorsal raphe (B6/B7) - rostral ventromedial medulla (B3) - spinal dorsal horn includes serotonergic system. However, possible role of supralemniscal (B9) serotonin (5-HT) cell group in pain management is still open question. In this study, we measured activities of B9 5-HT neuronal cell bodies and B9 5-HT neuron-derived axons located in the locus coeruleus (LC) and ventral tegmental area (VTA), which are also main players of pain management, using fiber photometry system. We introduced the G-CaMP6 in B9 5-HT neurons using transgenic mice carrying a tetracycline-controlled transactivator transgene (tTA) under the control of a tryptophan hydroxylase-2 (TPH2) promoter and site-specific injection of adeno associated virus (AAV-TetO(3G)-G-CaMP6). After confirmation of specific expression of G-CaMP6 in the target population, G-CaMP6 fluorescence intensity in B9 group and LC/VTA groups was measured in awake mice exposed to acute tail pinch and heat stimuli. G-CaMP6 fluorescence intensity rapidly increased by both stimuli in all groups, but not significantly reacted by nonnociceptive control stimuli. The present results clearly indicate that acute nociceptive stimuli cause a rapid increase in the activities of B9-LC/B9-VTA 5-HTergic pathways, suggesting that B9 5-HT neurons play important roles in nociceptive processing.
Collapse
Affiliation(s)
- Shunpei Moriya
- Department of Physiology, Kagoshima University Graduate School of Medical and Dental Science, Kagoshima, 890-8544 Japan
| | - Akira Yamashita
- Department of Physiology, Kagoshima University Graduate School of Medical and Dental Science, Kagoshima, 890-8544 Japan
| | - Daiki Masukawa
- Department of Molecular Pharmacology and Neurobiology, Yokohama City University Graduate School of Medicine, Yokohama, 236-0004 Japan
| | - Yuki Kambe
- Department of Pharmacology, Kagoshima University Graduate School of Medical and Dental Science, Kagoshima, 890-8544 Japan
| | - Junichi Sakaguchi
- Department of Physiology, Kagoshima University Graduate School of Medical and Dental Science, Kagoshima, 890-8544 Japan
| | - Honami Setoyama
- Department of Physiology, Kagoshima University Graduate School of Medical and Dental Science, Kagoshima, 890-8544 Japan
| | - Akihiro Yamanaka
- Research Institute of Environmental Medicine, Nagoya University, Nagoya, 464-8601 Japan
| | - Tomoyuki Kuwaki
- Department of Physiology, Kagoshima University Graduate School of Medical and Dental Science, Kagoshima, 890-8544 Japan
| |
Collapse
|
7
|
Dornellas APS, Boldarine VT, Pedroso AP, Carvalho LOT, de Andrade IS, Vulcani-Freitas TM, dos Santos CCC, do Nascimento CMDPO, Oyama LM, Ribeiro EB. High-Fat Feeding Improves Anxiety-Type Behavior Induced by Ovariectomy in Rats. Front Neurosci 2018; 12:557. [PMID: 30233288 PMCID: PMC6129615 DOI: 10.3389/fnins.2018.00557] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 07/24/2018] [Indexed: 12/11/2022] Open
Abstract
Menopause-induced changes may include increased incidence of both depression/anxiety and obesity. We hypothesized that behavioral changes that may develop after ovarian failure could be related to neurochemical and metabolic aspects affected by this condition and that high-fat intake may influence these associations. The present study investigated in rats the effects of ovariectomy, either alone or combined with high-fat diets enriched with either lard or fish-oil, on metabolic, behavioral and monoaminergic statuses, and on gene expression of neuropeptides and receptors involved in energy balance and mood regulation. Female rats had their ovaries removed and received either standard chow (OvxC) or high-fat diets enriched with either lard (OvxL) or fish-oil (OvxF) for 8 weeks. The Sham group received only chow diet. Ovariectomy increased feed efficiency and body weight gain and impaired glucose homeostasis and serotonin-induced hypophagia, effects either maintained or even accentuated by the lard diet but counteracted by the fish diet. The OvxL group developed obesity and hyperleptinemia. Regarding components of hypothalamic serotonergic system, both ovariectomy alone or combined with the fish diet increased 5-HT2C expression while the lard diet reduced 5-HT1B mRNA. Ovariectomy increased the anxiety index, as derived from the elevated plus maze test, while both high-fat groups showed normalization of this index. In the forced swimming test, ovariectomy allied to high-lard diet, but not to fish-oil diet, reduced the latency to immobility, indicating vulnerability to a depressive-like state. Linear regression analysis showed hippocampal AgRP to be negatively associated with the anxiety index and hypothalamic AgRP to be positively associated with the latency to immobility. These AgRp gene expression associations are indicative of a beneficial involvement of this neuropeptide on both depression and anxiety measures. The present findings demonstrate metabolic, neurochemical and behavioral alterations after ovaries removal and highlight a positive effect of high-fat feeding on the anxiety-like behavior shown by ovariectomized animals. Since the polyunsaturated ômega-3 intake (fish diet), unlike the saturated fat intake (lard diet), failed to induce deleterious metabolic or neurochemical consequences, further studies are needed focusing on the potential of this dietary component as an adjuvant anxiolytic agent after menopause.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | - Eliane B. Ribeiro
- Physiology Department, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, Brazil
| |
Collapse
|
8
|
Garcia R, Cotter AR, Leslie K, Olive MF, Neisewander JL. Preclinical Evidence That 5-HT1B Receptor Agonists Show Promise as Medications for Psychostimulant Use Disorders. Int J Neuropsychopharmacol 2017; 20:644-653. [PMID: 28444326 PMCID: PMC5570061 DOI: 10.1093/ijnp/pyx025] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 04/18/2017] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND 5-HT1B receptor agonists enhance cocaine intake during daily self-administration sessions but decrease cocaine intake when tested after prolonged abstinence. We examined if 5-HT1B receptor agonists produce similar abstinence-dependent effects on methamphetamine intake. METHODS Male rats were trained to self-administer methamphetamine (0.1 mg/kg, i.v.) on low (fixed ratio 5 and variable ratio 5) and high (progressive ratio) effort schedules of reinforcement until intake was stable. Rats were then tested for the effects of the selective 5-HT1B receptor agonist, CP 94,253 (5.6 or 10 mg/kg), or the less selective but clinically available 5-HT1B/1D receptor agonist, zolmitriptan (10 mg/kg), on methamphetamine self-administration both before and after a 21-day forced abstinence period during which the rats remained in their home cages. RESULTS The inverted U-shaped, methamphetamine dose-response function for intake on the fixed ratio 5 schedule was shifted downward by CP 94,253 both before and after abstinence. The CP 94,253-induced decrease in methamphetamine intake was replicated in rats tested on a variable ratio 5 schedule, and the 5-HT1B receptor antagonist SB 224,289 (10 mg/kg) reversed this effect. CP 94,253 also attenuated methamphetamine intake on a progressive ratio schedule both pre- and postabstinence. Similarly, zolmitriptan attenuated methamphetamine intake on a variable ratio 5 schedule both pre- and postabstinence, and the latter effect was sustained after each of 2 more treatments given every 2 to 3 days prior to daily sessions. CONCLUSIONS Unlike the abstinence-dependent effect of 5-HT1B receptor agonists on cocaine intake reported previously, both CP 94,253 and zolmitriptan decreased methamphetamine intake regardless of abstinence. These findings suggest that 5-HT1B receptor agonists may have clinical efficacy for psychostimulant use disorders.
Collapse
Affiliation(s)
- Raul Garcia
- School of Life Sciences (Mr Garcia, Mr Cotter, Mr Leslie, and Dr Neisewander), and Psychology Department (Dr Olive), Arizona State University, Tempe, Arizona
| | - Austin R Cotter
- School of Life Sciences (Mr Garcia, Mr Cotter, Mr Leslie, and Dr Neisewander), and Psychology Department (Dr Olive), Arizona State University, Tempe, Arizona
| | - Kenneth Leslie
- School of Life Sciences (Mr Garcia, Mr Cotter, Mr Leslie, and Dr Neisewander), and Psychology Department (Dr Olive), Arizona State University, Tempe, Arizona
| | - M Foster Olive
- School of Life Sciences (Mr Garcia, Mr Cotter, Mr Leslie, and Dr Neisewander), and Psychology Department (Dr Olive), Arizona State University, Tempe, Arizona
| | - Janet L Neisewander
- School of Life Sciences (Mr Garcia, Mr Cotter, Mr Leslie, and Dr Neisewander), and Psychology Department (Dr Olive), Arizona State University, Tempe, Arizona
| |
Collapse
|
9
|
Abstract
The role of serotonin in major depressive disorder (MDD) is the focus of accumulating clinical and preclinical research. The results of these studies reflect the complexity of serotonin signaling through many receptors, in a large number of brain regions, and throughout the lifespan. The role of the serotonin transporter in MDD has been highlighted in gene by environment association studies as well as its role as a critical player in the mechanism of the most effective antidepressant treatments – selective serotonin reuptake inhibitors. While the majority of the 15 known receptors for serotonin have been implicated in depression or depressive-like behavior, the serotonin 1A (5-HT
1A) and 1B (5-HT
1B) receptors are among the most studied. Human brain imaging and genetic studies point to the involvement of 5-HT
1A and 5-HT
1B receptors in MDD and the response to antidepressant treatment. In rodents, the availability of tissue-specific and inducible knockout mouse lines has made possible the identification of the involvement of 5-HT
1A and 5-HT
1B receptors throughout development and in a cell-type specific manner. This, and other preclinical pharmacology work, shows that autoreceptor and heteroreceptor populations of these receptors have divergent roles in modulating depression-related behavior as well as responses to antidepressants and also have different functions during early postnatal development compared to during adulthood.
Collapse
Affiliation(s)
- Katherine M Nautiyal
- Division of Integrative Neuroscience, New York State Psychiatric Institute, and Department of Psychiatry, Columbia University, NY, USA
| | - René Hen
- Division of Integrative Neuroscience, New York State Psychiatric Institute, and Department of Psychiatry, Columbia University, NY, USA; Departments of Neuroscience and Pharmacology, Columbia University, NY, USA
| |
Collapse
|
10
|
Nautiyal KM, Tritschler L, Ahmari SE, David DJ, Gardier AM, Hen R. A Lack of Serotonin 1B Autoreceptors Results in Decreased Anxiety and Depression-Related Behaviors. Neuropsychopharmacology 2016; 41:2941-2950. [PMID: 27353308 PMCID: PMC5061886 DOI: 10.1038/npp.2016.109] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 06/17/2016] [Accepted: 06/21/2016] [Indexed: 12/11/2022]
Abstract
The effects of serotonin (5-HT) on anxiety and depression are mediated by a number of 5-HT receptors, including autoreceptors that act to inhibit 5-HT release. While the majority of anxiety and depression-related research has focused on the 5-HT1A receptor, the 5-HT1B receptor has a lesser known role in modulating emotional behavior. 5-HT1B receptors are inhibitory GPCRs located on the presynaptic terminal of both serotonin and non-serotonin neurons, where they act to inhibit neurotransmitter release. The autoreceptor population located on the axon terminals of 5-HT neurons is a difficult population to study due to their diffuse localization throughout the brain that overlaps with 5-HT1B heteroreceptors (receptors located on non-serotonergic neurons). In order to study the contribution of 5-HT1B autoreceptors to anxiety and depression-related behaviors, we developed a genetic mouse model that allows for selective ablation of 5-HT1B autoreceptors. Mice lacking 5-HT1B autoreceptors displayed the expected increases in extracellular serotonin levels in the ventral hippocampus following administration of a selective serotonin reuptake inhibitor. In behavioral studies, they displayed decreased anxiety-like behavior in the open field and antidepressant-like effects in the forced swim and sucrose preference tests. These results suggest that strategies aimed at blocking 5-HT1B autoreceptors may be useful for the treatment of anxiety and depression.
Collapse
Affiliation(s)
- Katherine M Nautiyal
- Department of Psychiatry, Columbia University, New York, NY, USA,Division of Integrative Neuroscience, The New York State Psychiatric Institute, New York, NY, USA
| | - Laurent Tritschler
- Université Paris-Saclay, University Paris-Sud, Faculté de Pharmacie, CESP, INSERM UMRS1178, Chatenay-Malabry, France
| | - Susanne E Ahmari
- Department of Psychiatry, Translational Neuroscience Program, Center for Neuroscience Program, Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA, USA
| | - Denis J David
- Université Paris-Saclay, University Paris-Sud, Faculté de Pharmacie, CESP, INSERM UMRS1178, Chatenay-Malabry, France
| | - Alain M Gardier
- Université Paris-Saclay, University Paris-Sud, Faculté de Pharmacie, CESP, INSERM UMRS1178, Chatenay-Malabry, France
| | - René Hen
- Department of Psychiatry, Columbia University, New York, NY, USA,Division of Integrative Neuroscience, The New York State Psychiatric Institute, New York, NY, USA,Department of Neuroscience, Columbia University, New York, NY, USA,Center for Neurobiology and Behavior, Columbia University, 722 W 168th St, P.I. Annex 731, 1051 Riverside Drive, Unit 87, New York, NY 10032-2695, USA, Tel: +1 646 774 7108, Fax: +1 646 774 7102, E-mail:
| |
Collapse
|
11
|
Hiroi R, Carbone DL, Zuloaga DG, Bimonte-Nelson HA, Handa RJ. Sex-dependent programming effects of prenatal glucocorticoid treatment on the developing serotonin system and stress-related behaviors in adulthood. Neuroscience 2016; 320:43-56. [PMID: 26844389 PMCID: PMC4840233 DOI: 10.1016/j.neuroscience.2016.01.055] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Revised: 01/12/2016] [Accepted: 01/26/2016] [Indexed: 12/25/2022]
Abstract
Prenatal stress and overexposure to glucocorticoids (GC) during development may be associated with an increased susceptibility to a number of diseases in adulthood including neuropsychiatric disorders, such as depression and anxiety. In animal models, prenatal overexposure to GC results in hyper-responsiveness to stress in adulthood, and females appear to be more susceptible than males. Here, we tested the hypothesis that overexposure to GC during fetal development has sex-specific programming effects on the brain, resulting in altered behaviors in adulthood. We examined the effects of dexamethasone (DEX; a synthetic GC) during prenatal life on stress-related behaviors in adulthood and on the tryptophan hydroxylase-2 (TpH2) gene expression in the adult dorsal raphe nucleus (DRN). TpH2 is the rate-limiting enzyme for serotonin (5-HT) synthesis and has been implicated in the etiology of human affective disorders. Timed-pregnant rats were treated with DEX from gestational days 18-22. Male and female offspring were sacrificed on the day of birth (postnatal day 0; P0), P7, and in adulthood (P80-84) and brains were examined for changes in TpH2 mRNA expression. Adult animals were also tested for anxiety- and depressive- like behaviors. In adulthood, prenatal DEX increased anxiety- and depressive- like behaviors selectively in females, as measured by decreased time spent in the center of the open field and increased time spent immobile in the forced swim test, respectively. Prenatal DEX increased TpH2 mRNA selectively in the female caudal DRN at P7, whereas it decreased TpH2 mRNA selectively in the female caudal DRN in adulthood. In animals challenged with restraint stress in adulthood, TpH2 mRNA was significantly lower in rostral DRN of prenatal DEX-treated females compared to vehicle-treated females. These data demonstrated that prenatal overexposure to GC alters the development of TpH2 gene expression and these alterations correlated with lasting behavioral changes found in adult female offspring.
Collapse
Affiliation(s)
- R Hiroi
- Basic Medical Sciences, University of Arizona College of Medicine - Phoenix, 550 E. Van Buren Street, Phoenix, AZ 85004, USA; Department of Psychology, Arizona State University, 950 S. McAllister Avenue, Tempe, AZ 85287, USA.
| | - D L Carbone
- Basic Medical Sciences, University of Arizona College of Medicine - Phoenix, 550 E. Van Buren Street, Phoenix, AZ 85004, USA.
| | - D G Zuloaga
- Basic Medical Sciences, University of Arizona College of Medicine - Phoenix, 550 E. Van Buren Street, Phoenix, AZ 85004, USA.
| | - H A Bimonte-Nelson
- Department of Psychology, Arizona State University, 950 S. McAllister Avenue, Tempe, AZ 85287, USA.
| | - R J Handa
- Basic Medical Sciences, University of Arizona College of Medicine - Phoenix, 550 E. Van Buren Street, Phoenix, AZ 85004, USA.
| |
Collapse
|
12
|
Pickard GE, So KF, Pu M. Dorsal raphe nucleus projecting retinal ganglion cells: Why Y cells? Neurosci Biobehav Rev 2015; 57:118-31. [PMID: 26363667 PMCID: PMC4646079 DOI: 10.1016/j.neubiorev.2015.08.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 06/30/2015] [Accepted: 08/01/2015] [Indexed: 10/23/2022]
Abstract
Retinal ganglion Y (alpha) cells are found in retinas ranging from frogs to mice to primates. The highly conserved nature of the large, fast conducting retinal Y cell is a testament to its fundamental task, although precisely what this task is remained ill-defined. The recent discovery that Y-alpha retinal ganglion cells send axon collaterals to the serotonergic dorsal raphe nucleus (DRN) in addition to the lateral geniculate nucleus (LGN), medial interlaminar nucleus (MIN), pretectum and the superior colliculus (SC) has offered new insights into the important survival tasks performed by these cells with highly branched axons. We propose that in addition to its role in visual perception, the Y-alpha retinal ganglion cell provides concurrent signals via axon collaterals to the DRN, the major source of serotonergic afferents to the forebrain, to dramatically inhibit 5-HT activity during orientation or alerting/escape responses, which dis-facilitates ongoing tonic motor activity while dis-inhibiting sensory information processing throughout the visual system. The new data provide a fresh view of these evolutionarily old retinal ganglion cells.
Collapse
Affiliation(s)
- Gary E Pickard
- School of Veterinary Medicine and Biomedical Sciences, University of Nebraska, Lincoln, NE, 68583, United States; Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE, 68198, United States; GHM Institute of CNS Regeneration, Jinan University, Guangzhou, China
| | - Kwok-Fai So
- Department of Biomedical Sciences, The University of Hong Kong, Pokfulam, Hong Kong, China; Department of Ophthalmology, The University of Hong Kong, Hong Kong, China; GHM Institute of CNS Regeneration, Jinan University, Guangzhou, China; State Key Laboratory for Brain and Cognitive Sciences, The University of Hong Kong, Hong Kong, China.
| | - Mingliang Pu
- Department of Anatomy and Embryology, School of Basic Medical Sciences, Peking University, Beijing, China; Key Laboratory on Machine Perception (Ministry of Education), Peking University, Beijing, China; Key Laboratory for Visual Impairment and Restoration (Ministry of Education), Peking University, Beijing, China.
| |
Collapse
|
13
|
5-HT1A receptor-dependent control of nigrostriatal dopamine neurotransmission in the pharmacotherapy of Parkinson’s disease and schizophrenia. Behav Pharmacol 2015; 26:45-58. [DOI: 10.1097/fbp.0000000000000123] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
14
|
Serotonin in anxiety and panic: Contributions of the elevated T-maze. Neurosci Biobehav Rev 2014; 46 Pt 3:397-406. [DOI: 10.1016/j.neubiorev.2014.03.007] [Citation(s) in RCA: 93] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 02/05/2014] [Accepted: 03/03/2014] [Indexed: 11/21/2022]
|
15
|
Chung S, Kim HJ, Kim HJ, Choi SH, Cho JH, Cho YH, Kim DH, Shin KH. Desipramine and citalopram attenuate pretest swim-induced increases in prodynorphin immunoreactivity in the dorsal bed nucleus of the stria terminalis and the lateral division of the central nucleus of the amygdala in the forced swimming test. Neuropeptides 2014; 48:273-80. [PMID: 25129807 DOI: 10.1016/j.npep.2014.07.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/09/2013] [Revised: 07/03/2014] [Accepted: 07/15/2014] [Indexed: 01/02/2023]
Abstract
Dynorphin in the nucleus accumbens shell plays an important role in antidepressant-like effect in the forced swimming test (FST), but it is unclear whether desipramine and citalopram treatments alter prodynorphin levels in other brain areas. To explore this possibility, we injected mice with desipramine and citalopram 0.5, 19, and 23 h after a 15-min pretest swim and observed changes in prodynorphin expression before the test swim, which was conducted 24 h after the pretest swim. The pretest swim increased prodynorphin immunoreactivity in the dorsal bed nucleus of the stria terminalis (dBNST) and lateral division of the central nucleus of the amygdala (CeL). This increase in prodynorphin immunoreactivity in the dBNST and CeL was blocked by desipramine and citalopram treatments. Similar changes in prodynorphin mRNA levels were observed in the dBNST and CeL, but these changes did not reach significance. To understand the underlying mechanism, we assessed changes in phosphorylated CREB at Ser(133) (pCREB) immunoreactivity in the dBNST and central nucleus of the amygdala (CeA). Treatment with citalopram but not desipramine after the pretest swim significantly increased pCREB immunoreactivity only in the dBNST. These results suggest that regulation of prodynorphin in the dBNST and CeL before the test swim may be involved in the antidepressant-like effect of desipramine and citalopram in the FST and suggest that changes in pCREB immunoreactivity in these areas may not play an important role in the regulation of prodynorphin in the dBNST and CeA.
Collapse
Affiliation(s)
- Sung Chung
- Department of Pharmacology, Korea University College of Medicine, Anam-Dong, Sungbuk-Gu, Seoul, Republic of Korea
| | - Hee Jeong Kim
- Department of Pharmacology, Korea University College of Medicine, Anam-Dong, Sungbuk-Gu, Seoul, Republic of Korea
| | - Hyun Ju Kim
- Department of Pharmacology, Korea University College of Medicine, Anam-Dong, Sungbuk-Gu, Seoul, Republic of Korea
| | - Sun Hye Choi
- Department of Pharmacology, Korea University College of Medicine, Anam-Dong, Sungbuk-Gu, Seoul, Republic of Korea
| | - Jin Hee Cho
- Department of Pharmacology, Korea University College of Medicine, Anam-Dong, Sungbuk-Gu, Seoul, Republic of Korea
| | - Yun Ha Cho
- Department of Pharmacology, Korea University College of Medicine, Anam-Dong, Sungbuk-Gu, Seoul, Republic of Korea
| | - Dong-Hoon Kim
- Department of Pharmacology, Korea University College of Medicine, Anam-Dong, Sungbuk-Gu, Seoul, Republic of Korea
| | - Kyung Ho Shin
- Department of Pharmacology, Korea University College of Medicine, Anam-Dong, Sungbuk-Gu, Seoul, Republic of Korea.
| |
Collapse
|
16
|
Navailles S, Guillem K, Vouillac-Mendoza C, Ahmed SH. Coordinated Recruitment of Cortical–Subcortical Circuits and Ascending Dopamine and Serotonin Neurons During Inhibitory Control of Cocaine Seeking in Rats. Cereb Cortex 2014; 25:3167-81. [DOI: 10.1093/cercor/bhu112] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
|
17
|
Vasudeva RK, Waterhouse BD. Cellular profile of the dorsal raphe lateral wing sub-region: relationship to the lateral dorsal tegmental nucleus. J Chem Neuroanat 2014; 57-58:15-23. [PMID: 24704911 DOI: 10.1016/j.jchemneu.2014.03.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2013] [Revised: 02/25/2014] [Accepted: 03/04/2014] [Indexed: 01/09/2023]
Abstract
As one of the main serotonergic (5HT) projections to the forebrain, the dorsal raphe nucleus (DRN) has been implicated in disorders of anxiety and depression. Although the nucleus contains the densest population of 5HT neurons in the brain, at least 50% of cells within this structure are non-serotonergic, including a large population of nitric oxide synthase (NOS) containing neurons. The DRN has a unique topographical efferent organization and can also be divided into sub-regions based on rostro-caudal and medio-lateral dimensions. NOS is co-localized with 5HT in the midline DRN but NOS-positive cells in the lateral wing (LW) of the nucleus do not express 5HT. Interestingly, the NOS LW neuronal population is immediately rostral to and in line with the cholinergic lateral dorsal tegmental nucleus (LDT). We used immunohistochemical methods to investigate the potential serotonergic regulation of NOS LW neurons and also the association of this cell grouping to the LDT. Our results indicate that >75% of NOS LW neurons express the inhibitory 5HT1A receptor and are cholinergic (>90%). The findings suggest this assembly of cells is a rostral extension of the LDT, one that it is subject to regulation by 5HT release. As such the present study suggests a link between 5HT signaling, activation of cholinergic/NOS neurons, and the stress response including the pathophysiology underlying anxiety and depression.
Collapse
Affiliation(s)
- Rani K Vasudeva
- Temple University School of Medicine, Center for Substance Abuse Research, MERB 8th Floor, Philadelphia, PA 19140, United States; Drexel University College of Medicine, Department of Neurobiology & Anatomy, Queen Lane Campus, Philadelphia, PA 19129, United States.
| | - Barry D Waterhouse
- Drexel University College of Medicine, Department of Neurobiology & Anatomy, Queen Lane Campus, Philadelphia, PA 19129, United States.
| |
Collapse
|
18
|
Zepf FD, Sánchez CL, Biskup CS, Kötting WF, Bubenzer S, Helmbold K, Eisert A, Gaber TJ, Landgraf M, Dahmen B, Poustka F, Wöckel L, Stadler C, Grabemann M, Mette C, Heinrich V, Uekermann J, Abdel-Hamid M, Kis B, Zimmermann M, Wiltfang J, Kuhn CM. Acute tryptophan depletion - converging evidence for decreasing central nervous serotonin synthesis in rodents and humans. Acta Psychiatr Scand 2014; 129:157-9. [PMID: 24237607 DOI: 10.1111/acps.12215] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- F D Zepf
- Clinic for Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, RWTH Aachen University, Aachen, Germany; JARA Translational Brain Medicine, Aachen, Jülich, Germany; Institute for Neuroscience and Medicine, Jülich Research Centre, Jülich, Germany.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Abstract
Although the role of the median raphe nucleus (MRN) in the regulation of anxiety has received less attention than that of the dorsal raphe nucleus (DRN) there is substantial evidence supporting this function. Reported results with different animal models of anxiety in rats show that whereas inactivation of serotonergic neurons in the MRN causes anxiolysis, the stimulation of the same neurons is anxiogenic. In particular, studies using the elevated T-maze comparing serotonergic interventions in the MRN and in the DRN indicate that the former affect only the inhibitory avoidance task, which has been related to generalized anxiety. In contrast, similar operations in the DRN change both the inhibitory avoidance and the one-way escape task, the latter being representative of panic disorder. Simultaneous injections of 5-HT-acting drugs in the MRN and in the dorsal hippocampus (DH) suggest that the MRN-DH pathway mediates the regulatory function of the MRN in anxiety. Overall, the results discussed in this review point to a relevant role of the MRN in the regulation of anxiety, but not panic, through the 5-HT pathway that innervates the DH.
Collapse
Affiliation(s)
- Telma Gcs Andrade
- 1Department of Biological Science, São Paulo State University-UNESP, Assis, Brazil
| | | | | |
Collapse
|
20
|
Haleem DJ. Extending therapeutic use of psychostimulants: focus on serotonin-1A receptor. Prog Neuropsychopharmacol Biol Psychiatry 2013; 46:170-80. [PMID: 23906987 DOI: 10.1016/j.pnpbp.2013.07.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Revised: 07/02/2013] [Accepted: 07/16/2013] [Indexed: 11/19/2022]
Abstract
INTRODUCTION Despite a number of medicinally important pharmacological effects, the therapeutic use of psychostimulants is limited because of abuse potential and psychosis following long term use. Development of pharmacological agents for improving and extending therapeutic use of psychostimulants in narcolepsy, attention deficit hyperactivity disorder, Parkinson's disease, obesity and as cognitive enhancer is an important research imperative. In this regard, one potential target system is the 5-hydroxytryptamine (5-HT; serotonin) neurotransmitter system. The focus of the present article is to evaluate a potential role of 5-HT-1A receptor in the alleviation of abuse potential and psychosis-induced by prescription psychostimulants amphetamines and apomorphine. METHOD Synaptic contacts between dopamine systems and 5-HT-1A receptors are traced. Studies on serotonin-1A influences on the modulation of dopamine neurotransmission and psychostimulant-induced behavioral sensitization are accumulated. RESULTS Inhibition of amphetamine and apomorphine-induced behavioral sensitization by co administration of 5-HT-1A agonists cannot be explained in terms of direct activation of 5-HT-1A receptors, because activation of pre- as well as postsynaptic 5-HT-1A receptors tends to increase dopamine neurotransmission. CONCLUSION Long term use of amphetamine and apomorphine produces adaptive changes in 5-HT-1A receptor mediated functions, which are prevented by the co-use of 5-HT-1A agonists. In view of extending medicinal use of psychostimulants, it is important to evaluate the effects of co-use of 5-HT-1A agonists on potential therapeutic profile of amphetamine and apomorphine in preclinical research. It is also important to evaluate the functional significance of 5-HT-1A receptors on psychostimulant-induced behaviors in other addiction models such as drug self-administration and reinstatement of drug seeking behavior.
Collapse
Affiliation(s)
- Darakhshan Jabeen Haleem
- Neuroscience Research Laboratory, Dr Panjwani Center for Molecular Medicine & Drug Research (PCMD), International Center for Chemical and Biological Science (ICCBS), University of Karachi, Karachi 75270, Pakistan.
| |
Collapse
|
21
|
Schenk S, Abraham B, Aronsen D, Colussi-Mas J, Do J. Effects of repeated exposure to MDMA on 5HT1a autoreceptor function: behavioral and neurochemical responses to 8-OHDPAT. Psychopharmacology (Berl) 2013; 227:355-61. [PMID: 23354536 DOI: 10.1007/s00213-013-2980-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Accepted: 12/20/2012] [Indexed: 11/28/2022]
Abstract
A consistent effect of repeated exposure to 3,4 methylenedioxymethamphetamine (MDMA) is a decrease in the tissue levels of serotonin (5-HT). A variety of behavioural and neurochemical tests were conducted to determine whether the tissue deficits were accompanied by an increased sensitivity of the 5-HT1a autoreceptor. Tests were conducted 2 weeks following MDMA exposure (four injections of 10.0 mg/kg, IP, administered at 2-h intervals in a single day). The response to the 5-HT1a agonist, 8-OHDPAT (0.003-0.5 mg/kg, SC), was assessed using lower lip retraction (LLR), hypoactivity, and 5-hydroxytryptophan (5-HTP) accumulation following decarboxylase inhibition. The 8-OHDPAT produced a dose-dependent increase in LLR and hypoactivity, but these effects were comparable for MDMA and saline pretreated groups. MDMA decreased tissue levels of 5-HT and the accumulation of 5-HTP, but these effects were not reflected in the changes in autoreceptor sensitivity. The data suggest that the decrease in tissue levels of 5-HT produced by MDMA is accompanied by a decrease in tryptophan hydroxylase activity but cannot be explained by supersensitivity of the 5-HT1a autoreceptor.
Collapse
Affiliation(s)
- Susan Schenk
- School of Psychology, Victoria University of Wellington, P.O. Box 600, Wellington, New Zealand.
| | | | | | | | | |
Collapse
|
22
|
Lesch KP, Araragi N, Waider J, van den Hove D, Gutknecht L. Targeting brain serotonin synthesis: insights into neurodevelopmental disorders with long-term outcomes related to negative emotionality, aggression and antisocial behaviour. Philos Trans R Soc Lond B Biol Sci 2012; 367:2426-43. [PMID: 22826343 DOI: 10.1098/rstb.2012.0039] [Citation(s) in RCA: 91] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Aggression, which comprises multi-faceted traits ranging from negative emotionality to antisocial behaviour, is influenced by an interaction of biological, psychological and social variables. Failure in social adjustment, aggressiveness and violence represent the most detrimental long-term outcome of neurodevelopmental disorders. With the exception of brain-specific tryptophan hydroxylase-2 (Tph2), which generates serotonin (5-HT) in raphe neurons, the contribution of gene variation to aggression-related behaviour in genetically modified mouse models has been previously appraised (Lesch 2005 Novartis Found Symp. 268, 111-140; Lesch & Merschdorf 2000 Behav. Sci. Law 18, 581-604). Genetic inactivation of Tph2 function in mice led to the identification of phenotypic changes, ranging from growth retardation and late-onset obesity, to enhanced conditioned fear response, increased aggression and depression-like behaviour. This spectrum of consequences, which are amplified by stress-related epigenetic interactions, are attributable to deficient brain 5-HT synthesis during development and adulthood. Human data relating altered TPH2 function to personality traits of negative emotionality and neurodevelopmental disorders characterized by deficits in cognitive control and emotion regulation are based on genetic association and are therefore not as robust as the experimental mouse results. Mouse models in conjunction with approaches focusing on TPH2 variants in humans provide unexpected views of 5-HT's role in brain development and in disorders related to negative emotionality, aggression and antisocial behaviour.
Collapse
Affiliation(s)
- Klaus-Peter Lesch
- Division of Molecular Psychiatry (MP), Laboratory of Translational Neuroscience (LTN), Department of Psychiatry, Psychosomatics, and Psychotherapy, University of Wuerzburg, , Fuechsleinstrasse 15, 97080 Wuerzburg, Germany.
| | | | | | | | | |
Collapse
|
23
|
Zhang J, Fan Y, Li Y, Zhu H, Wang L, Zhu MY. Chronic social defeat up-regulates expression of the serotonin transporter in rat dorsal raphe nucleus and projection regions in a glucocorticoid-dependent manner. J Neurochem 2012; 123:1054-68. [PMID: 23061525 DOI: 10.1111/jnc.12055] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2012] [Revised: 09/27/2012] [Accepted: 10/02/2012] [Indexed: 01/10/2023]
Abstract
Chronic stress and dysfunction of the serotonergic system in the brain have been considered two of the major risks for development of depression. In this study, adult Fischer 344 rats were subjected to a regimen of chronic social defeat (CSD). To mimic stressful conditions, some rats were not exposed to CSD, but instead treated with corticosterone (CORT) in oral solution while maintained in their home cage. Protein levels of the serotonin transporter (SERT) in the dorsal raphe nucleus (DRN), hippocampus, frontal cortex, and amygdala were examined by Western blotting or immunofluorescence staining. The results showed that CSD up-regulated SERT protein levels in the DRN, hippocampus, frontal cortex, and amygdala regions. This up-regulation was abolished or prevented by adrenalectomy, or treatment with antagonists of corticosteroid receptors mifepristone and spironolactone, alone or in combination. Similarly, up-regulated SERT protein levels in these brain regions were also observed in rats treated with oral CORT ingestion, which was analogously prevented by treatment with mifepristone and spironolactone. Furthermore, both CSD- and CORT-induced up-regulation of SERT protein levels in the DRN and three brain regions were attenuated by simultaneous treatment with fluoxetine, an antidepressant that specifically inhibits serotonin reuptake. The results indicate that up-regulation in SERT protein levels in the DRN and forebrain limbic structures caused by CSD regimen was mainly motivated by CORT through corticosteroid receptors. The present findings demonstrate that chronic stress is closely correlated with the serotonergic system by acting on the regulation of the SERT expression in the DRN and its projection regions, which may contribute to the development of depression.
Collapse
Affiliation(s)
- Jia Zhang
- Departments of Biomedical Sciences, Quillen College of Medicine, East Tennessee State University, Johnson City, Tennessee 37604, USA
| | | | | | | | | | | |
Collapse
|
24
|
Henry AM, Hohmann JG. High-resolution gene expression atlases for adult and developing mouse brain and spinal cord. Mamm Genome 2012; 23:539-49. [DOI: 10.1007/s00335-012-9406-2] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2012] [Accepted: 06/21/2012] [Indexed: 01/29/2023]
|
25
|
Mansur SS, Terenzi MG, Neto JM, Faria MS, Paschoalini MA. Alpha1 receptor antagonist in the median raphe nucleus evoked hyperphagia in free-feeding rats. Appetite 2011; 57:498-503. [DOI: 10.1016/j.appet.2011.06.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Revised: 06/08/2011] [Accepted: 06/24/2011] [Indexed: 10/18/2022]
|
26
|
High novelty-seeking predicts aggression and gene expression differences within defined serotonergic cell groups. Brain Res 2011; 1419:34-45. [PMID: 21925645 DOI: 10.1016/j.brainres.2011.08.038] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2011] [Revised: 08/11/2011] [Accepted: 08/16/2011] [Indexed: 11/21/2022]
Abstract
Aggression frequently coincides with specific dimensions of emotionality, such as impulsivity, risk-taking, and drug abuse. Serotonergic (5-HTergic) neurotransmission contributes to the regulation of numerous neurobiological functions, and is thought to play a key role in modulating aggressive responses. The current study uses selectively-bred High (bHR) and Low (bLR) Responder rats that exhibit differences in emotionality and behavioral control, with bHRs exhibiting heightened novelty-induced exploration, impulsivity, and increased sensitivity to drugs of abuse, and with bLRs characterized by exaggerated depressive- and anxiety-like behaviors. Based on this behavioral profile we hypothesized that bHR rats exhibit increased aggression along with changes in testosterone and corticosterone secretion characteristic of aggression, and that these changes are accompanied by alterations in the expression of key genes that regulate 5-HTergic neurotransmission (Tph2 and Sert) as well as in the activation of 5-HTergic cell groups following aggressive encounter. Our data demonstrate that when compared to bLR rats, bHRs express increased baseline Tph2 and Sert in select brainstem nuclei, and when tested on the resident-intruder test they exhibited: 1) increased aggressive behavior; 2) potentiated corticosterone and testosterone secretion; and 3) diminished intrusion-induced c-fos expression in select 5-HTergic brainstem cell groups. The most prominent gene expression differences occurred in the B9 cell group, pontomesencephalic reticular formation, median raphe, and the gigantocellular nucleus pars α. These data are consistent with the notion that altered 5-HT neurotransmission contributes to bHRs' heightened aggression. Furthermore, they indicate that a specific subset of brainstem 5-HTergic cell groups contributes to the regulation of intrusion-elicited behavioral responses.
Collapse
|
27
|
Waselus M, Valentino RJ, Van Bockstaele EJ. Collateralized dorsal raphe nucleus projections: a mechanism for the integration of diverse functions during stress. J Chem Neuroanat 2011; 41:266-80. [PMID: 21658442 PMCID: PMC3156417 DOI: 10.1016/j.jchemneu.2011.05.011] [Citation(s) in RCA: 96] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2011] [Revised: 05/18/2011] [Accepted: 05/20/2011] [Indexed: 01/01/2023]
Abstract
The midbrain dorsal raphe nucleus (DR) is the origin of the central serotonin (5-HT) system, a key neurotransmitter system that has been implicated in the expression of normal behaviors and in diverse psychiatric disorders, particularly affective disorders such as depression and anxiety. One link between the DR-5-HT system and affective disorders is exposure to stressors. Stress is a major risk factor for affective disorders, and stressors alter activity of DR neurons in an anatomically specific manner. Stress-induced changes in DR neuronal activity are transmitted to targets of the DR via ascending serotonergic projections, many of which collateralize to innervate multiple brain regions. Indeed, the collateralization of DR efferents allows for the coordination of diverse components of the stress response. This review will summarize our current understanding of the organization of the ascending DR system and its collateral projections. Using the neuropeptide corticotropin-releasing factor (CRF) system as an example of a stress-related initiator of DR activity, we will discuss how topographic specificity of afferent regulation of ascending DR circuits serves to coordinate activity in functionally diverse target regions under appropriate conditions.
Collapse
Affiliation(s)
- Maria Waselus
- Molecular and Behavioral Neuroscience Institute, University of Michigan, Ann Arbor, MI 48109, United States.
| | | | | |
Collapse
|
28
|
Jahanshahi A, Le Maitre E, Temel Y, Lanfumey L, Hamon M, Lesch KP, Tordera RM, Del Río J, Aso E, Maldonado R, Hökfelt T, Steinbusch HW. Altered expression of neuronal tryptophan hydroxylase-2 mRNA in the dorsal and median raphe nuclei of three genetically modified mouse models relevant to depression and anxiety. J Chem Neuroanat 2011; 41:227-33. [DOI: 10.1016/j.jchemneu.2011.05.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2011] [Revised: 05/22/2011] [Accepted: 05/25/2011] [Indexed: 02/08/2023]
|
29
|
Furay AR, McDevitt RA, Miczek KA, Neumaier JF. 5-HT1B mRNA expression after chronic social stress. Behav Brain Res 2011; 224:350-7. [PMID: 21718722 DOI: 10.1016/j.bbr.2011.06.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2011] [Revised: 06/10/2011] [Accepted: 06/14/2011] [Indexed: 12/28/2022]
Abstract
Chronic stress contributes to vulnerability for depression and drug addiction. The function of the serotonergic system has been found to be modified by chronic stress and these changes may play an important role in stress-related relapses to drug craving. The 5-HT(1B) receptor is expressed in nucleus accumbens (NAc) projection neurons and modulates drug reward mechanisms and there is evidence suggesting that stress alters the regulation and function of these receptors. To examine the role of these receptors in integrating the effects of stress on reward mechanisms, we examined whether chronic or acute social defeat stress (SDS) regulates 5-HT(1B) mRNA in dorsal and ventral striatum, regions that are critical for integrating the effects of environmental stressors on reward motivated behavior. In addition, 5-HT(1B) mRNA regulation in response to another acute stressor, inescapable tailshock, was measured. Our results indicate that intermittent and daily SDS procedures attenuated body weight gain, induced adrenal hypertrophy, and reduced the preference for saccharin, a sweet solution preferred by normal rats. There was a trend for daily, but not intermittent SDS to increase 5-HT(1B) receptor mRNA levels in nucleus accumbens. Therefore, in the next experiment, we examined daily SDS in greater detail and found that it increased 5-HT(1B) receptor mRNA expression in rostral nucleus accumbens shell, an area especially associated with reward functions. Neither acute SDS, nor acute tailshock stress had a significant impact on 5-HT(1B) mRNA expression in the striatum. Since increased 5-HT(1B) receptor expression in nucleus accumbens shell neurons can facilitate cocaine and alcohol reward mechanisms, this adaptation in endogenous 5-HT(1B) mRNA may be involved in the SDS-associated increase in vulnerability for developing addiction.
Collapse
Affiliation(s)
- Amy R Furay
- Department of Psychiatry and Behavioral Sciences, University of Washington, Harborview Medical Center, 300 9th Avenue, Seattle, WA 98104, USA.
| | | | | | | |
Collapse
|
30
|
McDevitt RA, Neumaier JF. Regulation of dorsal raphe nucleus function by serotonin autoreceptors: a behavioral perspective. J Chem Neuroanat 2011; 41:234-46. [PMID: 21620956 DOI: 10.1016/j.jchemneu.2011.05.001] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Revised: 04/22/2011] [Accepted: 05/02/2011] [Indexed: 11/26/2022]
Abstract
Neurotransmission by serotonin (5-HT) is tightly regulated by several autoreceptors that fine-tune serotonergic neurotransmission through negative feedback inhibition at the cell bodies (predominantly 5-HT(1A)) or at the axon terminals (predominantly 5-HT(1B)); however, more subtle roles for 5-HT(1D) and 5-HT(2B) autoreceptors have also been detected. This review provides an overview of 5-HT autoreceptors, focusing on their contribution in animal behavioral models of stress and emotion. Experiments targeting 5-HT autoreceptors in awake, behaving animals have generally shown that increasing autoreceptor feedback is anxiolytic and rewarding, while enhanced 5-HT function is aversive and anxiogenic; however, the role of serotonergic activity in behavioral models of helplessness is more complex. The prevailing model suggests that 5-HT autoreceptors become desensitized in response to stress exposure and antidepressant administration, two seemingly opposite manipulations. Thus there are still unresolved questions regarding the role of these receptors-and serotonin in general-in normal and pathological states.
Collapse
Affiliation(s)
- Ross A McDevitt
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA 98104, USA
| | | |
Collapse
|
31
|
Sperling R, Commons KG. Shifting topographic activation and 5-HT1A receptor-mediated inhibition of dorsal raphe serotonin neurons produced by nicotine exposure and withdrawal. Eur J Neurosci 2011; 33:1866-75. [PMID: 21501256 DOI: 10.1111/j.1460-9568.2011.07677.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nicotine activates serotonin [5-hydroxytryptamine (5-HT)] neurons innervating the forebrain, and this is thought to reduce anxiety. Nicotine withdrawal has also been associated with an activation of 5-HT neurotransmission, although withdrawal increases anxiety. In each case, 5-HT1A receptors have been implicated in the response. To determine whether there are different subgroups of 5-HT cells activated during nicotine administration and withdrawal, we mapped the appearance of Fos, a marker of neuronal activation, in 5-HT cells of the dorsal raphe nucleus (DR) and median raphe nucleus (MR). To understand the role of 5-HT1A receptor feedback inhibitory pathways in 5-HT cell activity during these conditions, we administered a selective 5-HT1A receptor antagonist and measured novel disinhibited Fos expression within 5-HT cells. Using these approaches, we found evidence that acute nicotine exposure activates 5-HT neurons rostrally and in the lateral wings of the DR, whereas there is 5-HT1A receptor-dependent inhibition of cells located ventrally at both the rostral level and mid-level. Previous chronic nicotine exposure did not modify the pattern of activation produced by acute nicotine exposure, but increased 5-HT1A receptor-dependent inhibition of 5-HT cells in the caudal DR. This pattern was nearly reversed during nicotine withdrawal, when there was evidence for caudal activation and mid-level and rostral 5-HT1A receptor-dependent inhibition. These results suggest that the distinct behavioral states produced by nicotine exposure and withdrawal correlate with reciprocal rostral-caudal patterns of activation and 5-HT1A receptor-mediated inhibition of DR 5-HT neurons. The complementary patterns of activation and inhibition suggest that 5-HT1A receptors may help to shape distinct topographic patterns of activation within the DR.
Collapse
Affiliation(s)
- Robin Sperling
- Department of Anesthesiology, Perioperative and Pain Medicine, Children's Hospital Boston, 300 Longwood Ave., Enders 307, Boston, MA 02115, USA
| | | |
Collapse
|
32
|
Serotonin 1B autoreceptors originating in the caudal dorsal raphe nucleus reduce expression of fear and depression-like behavior. Biol Psychiatry 2011; 69:780-7. [PMID: 21353664 PMCID: PMC3080128 DOI: 10.1016/j.biopsych.2010.12.029] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2010] [Revised: 12/15/2010] [Accepted: 12/15/2010] [Indexed: 12/27/2022]
Abstract
BACKGROUND Serotonin 1B (5-HT(1B)) autoreceptors regulate release of serotonin from terminals of dorsal raphe nucleus (DRN) projections. Expression of 5-HT(1B) in the DRN inversely correlates with behavioral measures of emotion, and viral-mediated overexpression of 5-HT(1B) receptors in the middle DRN inversely reduces measures of fear and anxiety in unstressed rats. Because the caudal subregion of the DRN is important in translating stress into emotional dysregulation, we explored behavioral functions of 5-HT(1B) autoreceptors in the caudal DRN. METHODS We manipulated 5-HT(1B) autoreceptor function in rats using either viral-mediated gene transfer into the caudal DRN or systemic injections of the 5-HT(1B) agonist 3-(1,2,5,6-tetrahydro-4-pyridyl)-5-propoxypyrrolo[3,2-b]pyridine (CP-94253). Rats were tested in forced swim test, open field test, and contextual fear conditioning. RESULTS Overexpression of 5-HT(1B) in the caudal DRN increased swimming in the forced swim test. It did not alter locomotion or thigmotaxis in the open field test but did reduce conditioned freezing. Freezing was reduced when 5-HT(1B) overexpression was present only during testing but not training. The CP-94253 exerted an inverted U-shaped dose response curve on conditioned freezing, with most pronounced effects seen at 1 mg/kg. At this dose, CP-94253 administered before a fear retention test reduced freezing both during that session and in subsequent drug-free testing, but only when drug was paired with re-exposure to the fear context. CONCLUSIONS The 5-HT(1B) autoreceptors originating in the caudal DRN regulate behavioral expression of helplessness and fear. Because systemic pharmacologic treatment with a 5-HT(1B) agonist facilitates reductions in fear, 5-HT(1B) receptors may be a target for the treatment of certain anxiety disorders.
Collapse
|
33
|
Monti JM. Serotonin control of sleep-wake behavior. Sleep Med Rev 2011; 15:269-81. [PMID: 21459634 DOI: 10.1016/j.smrv.2010.11.003] [Citation(s) in RCA: 343] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2010] [Revised: 11/27/2010] [Accepted: 11/28/2010] [Indexed: 11/19/2022]
Abstract
Based on electrophysiological, neurochemical, genetic and neuropharmacological approaches, it is currently accepted that serotonin (5-HT) functions predominantly to promote wakefulness (W) and to inhibit REM (rapid eye movement) sleep (REMS). Yet, under certain circumstances the neurotransmitter contributes to the increase in sleep propensity. Most of the serotonergic innervation of the cerebral cortex, amygdala, basal forebrain (BFB), thalamus, preoptic and hypothalamic areas, raphe nuclei, locus coeruleus and pontine reticular formation comes from the dorsal raphe nucleus (DRN). The 5-HT receptors can be classified into at least seven classes, designated 5-HT(1-7). The 5-HT(1A) and 5-HT(1B) receptor subtypes are linked to the inhibition of adenylate cyclase, and their activation evokes a membrane hyperpolarization. The actions of the 5-HT(2A), 5-HT(2B) and 5-HT(2C) receptor subtypes are mediated by the activation of phospholipase C, with a resulting depolarization of the host cell. The 5-HT(3) receptor directly activates a 5-HT-gated cation channel which leads to the depolarization of monoaminergic, aminoacidergic and cholinergic cells. The primary signal transduction pathway of 5-HT(6) and 5-HT(7) receptors is the stimulation of adenylate cyclase which results in the depolarization of the follower neurons. Mutant mice that do not express 5-HT(1A) or 5-HT(1B) receptor exhibit greater amounts of REMS than their wild-type counterparts, which could be related to the absence of a postsynaptic inhibitory effect on REM-on neurons of the laterodorsal and pedunculopontine tegmental nuclei (LDT/PPT). 5-HT(2A) and 5-HT(2C) receptor knock-out mice show a significant increase of W and a reduction of slow wave sleep (SWS) which has been ascribed to the increase of catecholaminergic neurotransmission involving mainly the noradrenergic and dopaminergic systems. Sleep variables have been characterized, in addition, in 5-HT(7) receptor knock-out mice; the mutants spend less time in REMS that their wild-type counterparts. Direct infusion of the 5-HT(1A) receptor agonists 8-OH-DPAT and flesinoxan into the DRN significantly enhances REMS in the rat. In contrast, microinjection of the 5-HT(1B) (CP-94253), 5-HT(2A/2C) (DOI), 5-HT(3) (m-chlorophenylbiguanide) and 5-HT(7) (LP-44) receptor agonists into the DRN induces a significant reduction of REMS. Systemic injection of full agonists at postsynaptic 5-HT(1A) (8-OH-DPAT, flesinoxan), 5-HT(1B) (CGS 12066B, CP-94235), 5-HT(2C) (RO 60-0175), 5-HT(2A/2C) (DOI, DOM), 5-HT(3) (m-chlorophenylbiguanide) and 5-HT(7) (LP-211) receptors increases W and reduces SWS and REMS. Of note, systemic administration of the 5-HT(2A/2C) receptor antagonists ritanserin, ketanserin, ICI-170,809 or sertindole at the beginning of the light period has been shown to induce a significant increase of SWS and a reduction of REMS in the rat. Wakefulness was also diminished in most of these studies. Similar effects have been described following the injection of the selective 5-HT(2A) receptor antagonists volinanserin and pruvanserin and of the 5-HT(2A) receptor inverse agonist nelotanserin in rodents. In addition, the effects of these compounds have been studied on the sleep electroencephalogram of subjects with normal sleep. Their administration was followed by an increase of SWS and, in most instances, a reduction of REMS. The administration of ritanserin to poor sleepers, patients with chronic primary insomnia and psychiatric patients with a generalized anxiety disorder or a mood disorder caused a significant increase in SWS. The 5-HT(2A) receptor inverse agonist APD-125 induced also an increase of SWS in patients with chronic primary insomnia. It is known that during the administration of benzodiazepine (BZD) hypnotics to patients with insomnia there is a further reduction of SWS and REMS, whereas both variables tend to remain decreased during the use of non-BZD derivatives (zolpidem, zopiclone, eszopiclone, zaleplon). Thus, the association of 5-HT(2A) antagonists or 5-HT(2A) inverse agonists with BZD and non-BZD hypnotics could be a valid alternative to normalize SWS in patients with primary or comorbid insomnia.
Collapse
Affiliation(s)
- Jaime M Monti
- Department of Pharmacology and Therapeutics, School of Medicine Clinics Hospital, Montevideo 11600, Uruguay.
| |
Collapse
|
34
|
Waider J, Araragi N, Gutknecht L, Lesch KP. Tryptophan hydroxylase-2 (TPH2) in disorders of cognitive control and emotion regulation: a perspective. Psychoneuroendocrinology 2011; 36:393-405. [PMID: 21257271 DOI: 10.1016/j.psyneuen.2010.12.012] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/02/2010] [Revised: 12/22/2010] [Accepted: 12/23/2010] [Indexed: 01/24/2023]
Abstract
Based on genetic variation, there is accumulating evidence that altered function of tryptophan hydroxylase-2 (TPH2), the enzyme critical for synthesis of serotonin (5-HT) in the brain, plays a role in anxiety-, aggression- and depression-related personality traits and in the pathogenesis of disorders featuring deficits in cognitive control and emotion regulation. Here, we appraise the genetic and neurobiological evidence to illustrate the critical role of TPH2 in central 5-HT system function and in the pathophysiology of a wide spectrum of disorders of cognitive control and emotion regulation, ranging from depression to attention-deficit/hyperactivity disorder (ADHD), a phenotype commonly associated with difficulties in the control of emotion and with a high co-morbidity of depression. Findings from psychophysiological and functional imaging studies are indicative of various TPH2 polymorphisms directly influencing serotonergic function and thus impacting on mood disorders and on the response to antidepressant treatment. Especially a combination with uncontrollable stress seems to potentiate these effects linking gene-environment interaction directly with behavioral dysfunction in human and animal models. TPH2-deficient mice display alterations in anxiety-like behavior which is accompanied by adaptational changes of 5-HT(1A) receptors and its associated signaling pathway. Mouse models in conjunction with cognitive neuroscience approaches in humans are providing unexpected results and it may well be that future research on TPH2 will provide an entirely new view of 5-HT in brain development and function related to neuropsychiatric disorders.
Collapse
Affiliation(s)
- Jonas Waider
- Molecular Psychiatry, Laboratory of Translational Neuroscience, Department of Psychiatry, Psychosomatics, and Psychotherapy, University of Wuerzburg, Fuechsleinstrasse 15, 97080 Wuerzburg, Germany
| | | | | | | |
Collapse
|
35
|
Hale MW, Lowry CA. Functional topography of midbrain and pontine serotonergic systems: implications for synaptic regulation of serotonergic circuits. Psychopharmacology (Berl) 2011; 213:243-64. [PMID: 21088958 DOI: 10.1007/s00213-010-2089-z] [Citation(s) in RCA: 174] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/17/2010] [Accepted: 10/29/2010] [Indexed: 12/20/2022]
Abstract
RATIONALE Dysfunction of serotonergic systems is thought to play an important role in a number of neurological and psychiatric disorders. Recent studies suggest that there is anatomical and functional diversity among serotonergic systems innervating forebrain systems involved in the control of physiologic and behavioral responses, including the control of emotional states. OBJECTIVE Here, we highlight the methods that have been used to investigate the heterogeneity of serotonergic systems and review the evidence for the unique anatomical, hodological, and functional properties of topographically organized subpopulations of serotonergic neurons in the midbrain and pontine raphe complex. CONCLUSION The emerging understanding of the topographically organized synaptic regulation of brainstem serotonergic systems, the topography of the efferent projections of these systems, and their functional properties, should enable identification of novel therapeutic approaches to treatment of neurological and psychiatric conditions that are associated with dysregulation of serotonergic systems.
Collapse
Affiliation(s)
- Matthew W Hale
- Department of Integrative Physiology, University of Colorado, Boulder, CO 80309-0354, USA
| | | |
Collapse
|
36
|
Hiroi R, McDevitt RA, Morcos PA, Clark MS, Neumaier JF. Overexpression or knockdown of rat tryptophan hyroxylase-2 has opposing effects on anxiety behavior in an estrogen-dependent manner. Neuroscience 2010; 176:120-31. [PMID: 21182901 DOI: 10.1016/j.neuroscience.2010.12.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 11/10/2010] [Accepted: 12/14/2010] [Indexed: 12/23/2022]
Abstract
Previous studies showed that chronic estrogen treatment increases tryptophan hydroxylase-2 (TpH2) mRNA in the caudal dorsal raphe nucleus (DRN), and this increase was associated with decreased anxiety. The present study explored the interaction of estrogen and targeted, bidirectional manipulation of TpH2 expression in the caudal DRN by knockdown or viral overexpression, to decrease or increase tryptophan hydroxylase expression respectively, on anxiety behavior. Rats were ovariectomized and replaced with empty or estradiol capsules (OVX, OVX/E, respectively). Animals received microinfusions of either antisense TpH2 or control morpholino oligonucleotides into caudal DRN and were later tested in the open field test. A separate group of animals were microinfused with TpH2-GFP or GFP-only herpes simplex viral vectors into caudal DRN and tested in the open field. The bidirectional impact of manipulations on TpH2 expression was confirmed using a combination of quantitative protein and mRNA measurements; TpH2 expression changes were limited to discrete subregions of DRN that were targeted by the manipulations. Estradiol decreased anxiety in all behavioral measures. In the OVX/E group, TpH2 knockdown significantly decreased time spent in the center of the open field, but not in the OVX group, suggesting that TpH2 knockdown reduced the anxiolytic effects of estrogen. Conversely, TpH2 overexpression in the OVX group mimicked the effects of estrogen, as measured by increased time spent in the center of the open field. These results suggest that estrogen and TpH2 in the caudal DRN have a critical interaction in regulating anxiety-like behavior.
Collapse
Affiliation(s)
- R Hiroi
- Department of Psychiatry and Behavioral Sciences, University of Washington, Seattle, WA 98195, USA
| | | | | | | | | |
Collapse
|
37
|
Fu W, Le Maître E, Fabre V, Bernard JF, David Xu ZQ, Hökfelt T. Chemical neuroanatomy of the dorsal raphe nucleus and adjacent structures of the mouse brain. J Comp Neurol 2010; 518:3464-94. [PMID: 20589909 DOI: 10.1002/cne.22407] [Citation(s) in RCA: 126] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Serotonin neurons play a major role in many normal and pathological brain functions. In the rat these neurons have a varying number of cotransmitters, including neuropeptides. Here we studied, with histochemical techniques, the relation between serotonin, some other small-molecule transmitters, and a number of neuropeptides in the dorsal raphe nucleus (DRN) and the adjacent ventral periaqueductal gray (vPAG) of mouse, an important question being to establish possible differences from rat. Even if similarly distributed, the serotonin neurons in mouse lacked the extensive coexpression of nitric oxide synthase and galanin seen in rat. Although partly overlapping in the vPAG, no evidence was obtained for the coexistence of serotonin with dopamine, substance P, cholecystokinin, enkephalin, somatostatin, neurotensin, dynorphin, thyrotropin-releasing hormone, or corticotropin-releasing hormone. However, some serotonin neurons expressed the gamma-aminobutyric acid (GABA)-synthesizing enzyme glutamic acid decarboxylase (GAD). Work in other laboratories suggests that, as in rat, serotonin neurons in the mouse midline DRN express the vesicular glutamate transporter 3, presumably releasing glutamate. Our study also shows that many of the neuropeptides studied (substance P, galanin, neurotensin, dynorphin, and corticotropin-releasing factor) are present in nerve terminal networks of varying densities close to the serotonin neurons, and therefore may directly or indirectly influence these cells. The apparently low numbers of coexisting messengers in mouse serotonin neurons, compared to rat, indicate considerable species differences with regard to the chemical neuronatomy of the DRN. Thus, extrapolation of DRN physiology, and possibly pathology, from rat to mouse, and even human, should be made with caution.
Collapse
Affiliation(s)
- Wenyu Fu
- Department of Neuroscience, Karolinska Institutet, 17177 Stockholm, Sweden
| | | | | | | | | | | |
Collapse
|
38
|
Sidor MM, Amath A, MacQueen G, Foster JA. A developmental characterization of mesolimbocortical serotonergic gene expression changes following early immune challenge. Neuroscience 2010; 171:734-46. [PMID: 20816924 DOI: 10.1016/j.neuroscience.2010.08.060] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2010] [Revised: 08/25/2010] [Accepted: 08/30/2010] [Indexed: 12/15/2022]
Abstract
An immunogenic challenge during early postnatal development leads to long-term changes in behavioural and physiological measures reflecting enhanced emotionality and anxiety. Altered CNS serotonin (5-HT) signalling during the third postnatal week is thought to modify the developing neurocircuitry governing anxiety-like behaviour. Changes in 5-HT signalling during this time window may underlie increased emotionality reported in early immune challenge rodents. Here we examine both the spatial and temporal profile of 5-HT related gene expression, including 5HT1A, 2A, 2C receptors, the 5-HT transporter (5HTT), and tryptophan hydroxylase 2 (TPH2) during early development (postnatal day [P]14, P17, P21, P28) in mice challenged with lipopolysaccharide (LPS) during the first postnatal week. Expression levels were measured using in situ hybridization in regions associated with mediating emotive behaviours: the dorsal raphe (DR), hippocampus, amygdala, and prefrontal cortex (PFC). Increased TPH2 and 5HTT expression in the ventrolateral region of the DR of LPS-mice accompanied decreased expression of ventral DR 5HT1A and dorsal DR 5HTT. In the forebrain, 5HT1A and 2A receptors were increased, whereas 5HT2C receptors were decreased in the hippocampus. Decreased mRNA expression of 5HT2C was detected in the amygdala and PFC of LPS-treated pups; 5HT1A was increased in the PFC. The majority of these changes were restricted to P14-21. These transient changes in 5-HT expression coincide with the critical time window in which 5-HT disturbance leads to permanent modification of anxiety-related behaviours. This suggests that alterations in CNS 5-HT during development may underlie the enhanced emotionality associated with an early immune challenge.
Collapse
Affiliation(s)
- M M Sidor
- Department of Psychiatry and Behavioural Neurosciences, McMaster University, Hamilton, ON, Canada
| | | | | | | |
Collapse
|
39
|
MacGillivray L, Lagrou LM, Reynolds KB, Rosebush PI, Mazurek MF. Role of serotonin transporter inhibition in the regulation of tryptophan hydroxylase in brainstem raphe nuclei: time course and regional specificity. Neuroscience 2010; 171:407-20. [PMID: 20868730 DOI: 10.1016/j.neuroscience.2010.08.055] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Revised: 08/17/2010] [Accepted: 08/23/2010] [Indexed: 01/17/2023]
Abstract
Drugs that selectively inhibit the serotonin transporter (SERT) are widely prescribed for treatment of depression and a range of anxiety disorders. We studied the time course of changes in tryptophan hydroxylase (TPH) in four raphe nuclei after initiation of two different SERT inhibitors, citalopram and fluoxetine. In the first experiment, groups of Sprague-Dawley rats received daily meals of rice pudding either alone (n=9) or mixed with citalopram 5 mg/kg/day (n=27). Rats were sacrificed after 24 h, 7 days or 28 days of treatment. Sections of dorsal raphe nucleus (DRN), median raphe nucleus (MRN), raphe magnus nucleus (RMN) and caudal linear nucleus (CLN) were processed for TPH immunohistochemistry. Citalopram induced a significant reduction in DRN TPH-positive cell counts at 24 h (41%), 7 days (38%) and 28 days (52%). Similar reductions in TPH-positive cell counts were also observed at each timepoint in the MRN and in the RMN. In the MRN, citalopram resulted in significant reductions at 24 h (26%), 7 days (16%) and 28 days (23%). In the RMN, citalopram induced significant reductions of TPH-positive cell counts at 24 h (45%), 7 days (34%) and 28 days (43%). By contrast, no significant differences between control and treatment groups were observed in the CLN at any of the time points that we studied. To investigate whether these changes would occur with other SERT inhibitors, we conducted a second experiment, this time with a 28-day course of fluoxetine. As was observed with citalopram, fluoxetine induced significant reductions of TPH cell counts in the DRN (39%), MRN (38%) and RMN (41%), with no significant differences in the CLN. These results indicate that SERT inhibition can alter the regulation of TPH, the rate limiting enzyme for serotonin biosynthesis. This persistent and regionally specific downregulation of serotonin biosynthesis may account for some of the clinical withdrawal symptoms associated with drugs that inhibit SERT.
Collapse
Affiliation(s)
- L MacGillivray
- Department of Medicine-Neurology, McMaster University Medical Centre, 1200 Main Street West, Hamilton, ON, L8N 3Z5, Canada.
| | | | | | | | | |
Collapse
|
40
|
Monti JM. The structure of the dorsal raphe nucleus and its relevance to the regulation of sleep and wakefulness. Sleep Med Rev 2010; 14:307-17. [PMID: 20153669 DOI: 10.1016/j.smrv.2009.11.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2009] [Revised: 11/15/2009] [Accepted: 11/16/2009] [Indexed: 11/30/2022]
Abstract
Serotonergic (5-HT) cells in the rat dorsal raphe nucleus (DRN) appear in topographically organized groups. Based on cellular morphology, expression of other neurotransmitters, afferent and efferent connections and functional properties, 5-HT neurons of the DRN have been grouped into six cell clusters. The subdivisions comprise the rostral, ventral, dorsal, lateral, caudal and interfascicular parts of the DRN. In addition to 5-HT cells, neurons containing γ-aminobutyric acid (GABA), glutamate, dopamine, nitric oxide and the neuropeptides corticotropin-releasing factor, substance P, galanin, cholecystokinin, neurotensin, somatostatin, vasoactive intestinal peptide, neuropeptide Y, thyrotropin-releasing hormone, growth hormone, leu-enkephalin, met-enkephalin and gastrin have been characterized in the DRN. Moreover, numerous brain areas have neurons that project to the DRN and express monoamines (norepinephrine, histamine), amino acids (GABA, glutamate), acetylcholine or neuropeptides (orexin, melanin-concentrating hormone, corticotropin-releasing factor and substance P) that directly or indirectly, through local circuits, regulate the activity of 5-HT cells. The 5-HT cells predominate along the midline of the rostral, dorsal and ventral subdivisions of the DRN and outnumber the non-5-HT cells occurring in the raphe nucleus. The GABAergic and glutamatergic neurons are clustered mainly in the lateral and dorsal subdivisions of the DRN, respectively. The 5-HT(1A) receptor is located on the soma and the dendrites of 5-HT neurons and at postsynaptic sites (outside the DRN). It is expressed, in addition, by non-5-HT cells of the DRN. The 5-HT(1B) receptor is located at presynaptic and postsynaptic sites (outside the boundaries of the DRN). It has been described also in the ventromedial DRN where it is expressed by non-5-HT cells. The 5-HT(2A) and 5-HT(2C) receptors are located within postsynaptic structures. At the level of the DRN the 5-HT(2A) and 5-HT(2C) receptor-containing cells are predominantly GABAergic interneurons and projection neurons. Within the boundaries of the DRN the 5-HT(3) receptor is expressed by, among others, glutamatergic interneurons. 5-HT(7) receptors in the DRN are not localized to serotonergic neurons but, at least in part, to GABAergic cells and terminals. The complex structure of the DRN may have important implications for neural mechanisms underlying 5-HT modulation of wakefulness and REM sleep.
Collapse
Affiliation(s)
- Jaime M Monti
- Department of Pharmacology and Therapeutics, School of Medicine Clinics Hospital, Montevideo, Uruguay.
| |
Collapse
|
41
|
Guimarães FS, Zangrossi H, Del Ben CM, Graeff FG. Serotonin in Panic and Anxiety Disorders. HANDBOOK OF BEHAVIORAL NEUROSCIENCE 2010. [DOI: 10.1016/s1569-7339(10)70105-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
|
42
|
Nexon L, Poirel VJ, Clesse D, Pévet P, Raison S. Complex regional influence of photoperiod on the nycthemeral functioning of the dorsal and median raphé serotoninergic system in the Syrian hamster. Eur J Neurosci 2009; 30:1790-801. [DOI: 10.1111/j.1460-9568.2009.06986.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
|
43
|
Hioki H, Nakamura H, Ma YF, Konno M, Hayakawa T, Nakamura KC, Fujiyama F, Kaneko T. Vesicular glutamate transporter 3-expressing nonserotonergic projection neurons constitute a subregion in the rat midbrain raphe nuclei. J Comp Neurol 2009; 518:668-86. [DOI: 10.1002/cne.22237] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
44
|
Mitchell ES, McDevitt RA, Neumaier JF. Adaptations in 5-HT receptor expression and function: Implications for treatment of cognitive impairment in aging. J Neurosci Res 2009; 87:2803-11. [DOI: 10.1002/jnr.22100] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
45
|
Fonseca FV, Mecawi AS, Araujo IG, Almeida-Pereira G, Magalhães-Nunes AP, Badauê-Passos D, Reis LC. Role of the 5-HT1A somatodendritic autoreceptor in the dorsal raphe nucleus on salt satiety signaling in rats. Exp Neurol 2009; 217:353-60. [DOI: 10.1016/j.expneurol.2009.03.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Revised: 03/13/2009] [Accepted: 03/14/2009] [Indexed: 02/04/2023]
|
46
|
Rivera HM, Oberbeck DR, Kwon B, Houpt TA, Eckel LA. Estradiol increases Pet-1 and serotonin transporter mRNA in the midbrain raphe nuclei of ovariectomized rats. Brain Res 2009; 1259:51-8. [PMID: 19168037 PMCID: PMC2957819 DOI: 10.1016/j.brainres.2008.12.067] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 12/29/2008] [Accepted: 12/31/2008] [Indexed: 01/04/2023]
Abstract
Previous research has shown that estradiol increases the anorexia associated with serotonin (5-HT) neurotransmission. To examine further the putative relationship between estradiol and 5-HT, we investigated whether estradiol increases the expression of Pet-1 and the 5-HT transporter (5-HTT), two genes implicated in the development and regulation of the 5-HT system. Ovariectomized (OVX) rats (n=5-6/group) were treated with 0, 2, or 10 microg estradiol benzoate (EB) in sesame oil on 2 consecutive days. Food intake and body weight were recorded 2 days later when EB-treated rats typically display signs of behavioral estrus (e.g., reduced feeding). Following the collection of behavioral data, rats were perfused, brains were removed, and coronal sections were cut through the midbrain raphe nuclei. Pet-1 and 5-HTT mRNA levels were quantified throughout the dorsal and median raphe nuclei (DRN and MRN) by conducting in situ hybridization on free-floating tissue sections using (35)S-labeled cDNA probes. As expected, EB treatment decreased food intake and body weight on the day that modeled estrus. At this same time, EB treatment increased Pet-1 and 5-HTT mRNA levels within the DRN and MRN. We conclude that a physiologically relevant regimen of estradiol treatment in OVX rats increases Pet-1 and 5-HTT mRNA levels in the midbrain raphe nuclei at a time when the anorexigenic effect of estradiol is apparent. Further studies are required to determine whether the increased expression of Pet-1 and 5-HTT mRNA plays a causal role in the anorexigenic effect of estradiol.
Collapse
Affiliation(s)
- Heidi M. Rivera
- Department of Psychology, Florida State University, Tallahassee, FL 32306-4301
| | - Denesa R. Oberbeck
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4340, USA
| | - Bumsup Kwon
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4340, USA
| | - Thomas A. Houpt
- Department of Biological Science, Florida State University, Tallahassee, FL 32306-4340, USA
| | - Lisa A. Eckel
- Department of Psychology, Florida State University, Tallahassee, FL 32306-4301
| |
Collapse
|
47
|
Thompson AM, Thompson GC. Experimental evidence that the serotonin transporter mediates serotonin accumulation in LSO neurons of the postnatal mouse. Brain Res 2008; 1253:60-8. [PMID: 19070605 DOI: 10.1016/j.brainres.2008.11.054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Revised: 11/07/2008] [Accepted: 11/07/2008] [Indexed: 12/29/2022]
Abstract
During the same postnatal period of development when their terminal projection patterns in the midbrain are maturing, lateral superior olivary (LSO) neurons are immunoreactive for serotonin (5-HT). As there is no evidence that LSO neurons synthesize 5-HT, it is likely that they accumulate 5-HT via the 5-HT transporter. To determine if the 5-HT transporter is responsible for 5-HT inside postnatal mouse LSO neurons, pups (postnatal ages 5-6) were treated with fluoxetine and LSO neurons examined for 5-HT. We also evaluated whether LSO neurons containing 5-HT expressed the 5-HT transporter. To further rule out any potential synthesis of 5-HT, brainstem sections of mice at postnatal ages when 5-HT staining is the most robust were stained for the rate-limiting enzyme in the synthesis of 5-HT, tryptophan hydroxylase. Fluoxetine treatment reduced or in most cases, completely eliminated the number of neurons in the LSO stained for 5-HT. Postnatal LSO neurons containing 5-HT were immunoreactive for the 5-HT transporter; in older animals in which 5-HT was no longer observed in the LSO neurons, 5-HT transporter expression was similarly absent. Further, LSO neurons in mice at any age did not stain for tryptophan hydroxylase. These results indicate that LSO neurons express the functional 5-HT transporter to internalize 5-HT; this mechanism may serve to regulate extracellular 5-HT levels during maturation of their terminal endings in the inferior colliculus.
Collapse
Affiliation(s)
- Ann M Thompson
- The University of Oklahoma Health Sciences Center, Department of Otorhinolaryngology, Oklahoma City, OK 73126-0901, USA.
| | | |
Collapse
|
48
|
Estrogen decreases 5-HT1B autoreceptor mRNA in selective subregion of rat dorsal raphe nucleus: inverse association between gene expression and anxiety behavior in the open field. Neuroscience 2008; 158:456-64. [PMID: 19049819 DOI: 10.1016/j.neuroscience.2008.10.016] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2008] [Revised: 10/10/2008] [Accepted: 10/14/2008] [Indexed: 12/30/2022]
Abstract
We have recently shown that estrogen decreases anxiety and increases expression of tryptophan hydroxylase-2 (TPH2), the rate-limiting enzyme for 5-HT synthesis. However, the effects of estrogen on 5-HT release and reuptake may also affect the overall availability of 5-HT in the forebrain. Estrogen has been previously shown to have no effect on the inhibitory 5-HT 1A autoreceptor (5-HT(1A)) in the rat dorsal raphe nuclei (DRN); however the regulation of the inhibitory 5-HT 1B autoreceptor (5-HT(1B)) in the midbrain raphe by estrogen has not yet been investigated. Therefore, we examined the effects of estrogen on 5-HT(1B) mRNA in the rat DRN, focusing on specific subregions, and whether 5-HT(1B) mRNA levels correlated with TPH2 mRNA levels and with anxiety-like behavior. Ovariectomized rats were treated for 2 weeks with estrogen or placebo, exposed to the open field test, and 5-HT(1A) and 5-HT(1B) mRNA was quantified by in situ hybridization histochemistry. Estrogen had no effect on 5HT(1A) mRNA in any of the DRN subregions examined, confirming a previous report. In contrast, estrogen selectively decreased 5-HT(1B) mRNA in the mid-ventromedial subregion of the DRN, where 5-HT(1B) mRNA was associated with higher anxiety-like behavior and inversely correlated with TPH2 mRNA levels. These results suggest that estrogen may reduce 5-HT(1B) autoreceptor and increase TPH2 synthesis in a coordinated fashion, thereby increasing the capacity for 5-HT synthesis and release in distinct forebrain regions that modulate specific components of anxiety behavior.
Collapse
|
49
|
Colussi-Mas J, Schenk S. Acute and sensitized response to 3,4-methylenedioxymethamphetamine in rats: different behavioral profiles reflected in different patterns of Fos expression. Eur J Neurosci 2008; 28:1895-910. [DOI: 10.1111/j.1460-9568.2008.06467.x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
50
|
Clark JA, Flick RB, Pai LY, Szalayova I, Key S, Conley RK, Deutch AY, Hutson PH, Mezey E. Glucocorticoid modulation of tryptophan hydroxylase-2 protein in raphe nuclei and 5-hydroxytryptophan concentrations in frontal cortex of C57/Bl6 mice. Mol Psychiatry 2008; 13:498-506. [PMID: 17622221 PMCID: PMC3392182 DOI: 10.1038/sj.mp.4002041] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Considerable attention has focused on regulation of central tryptophan hydroxylase (TPH) activity and protein expression. At the time of these earlier studies, it was thought that there was a single central TPH isoform. However, with the recent identification of TPH2, it becomes important to distinguish between regulatory effects on the protein expression and activity of the two isoforms. We have generated a TPH2-specific polyclonal antiserum (TPH2-6361) to study regulation of TPH2 at the protein level and to examine the distribution of TPH2 expression in rodent and human brain. TPH2 immunoreactivity (IR) was detected throughout the raphe nuclei, in lateral hypothalamic nuclei and in the pineal body of rodent and human brain. In addition, a prominent TPH2-IR fiber network was found in the human median eminence. We recently reported that glucocorticoid treatment of C57/Bl6 mice for 4 days markedly decreased TPH2 messenger RNA levels in the raphe nuclei, whereas TPH1 mRNA was unaffected. The glucocorticoid-elicited inhibition of TPH2 gene expression was blocked by co-administration of the glucocorticoid receptor antagonist mifepristone (RU-486). Using TPH2-6361, we have extended these findings to show a dose-dependent decrease in raphe TPH2 protein levels in response to 4 days of treatment with dexamethasone; this effect was blocked by co-administration of mifepristone. Moreover, the glucocorticoid-elicited inhibition of TPH2 was functionally significant: serotonin synthesis was significantly reduced in the frontal cortex of glucocorticoid-treated mice, an effect that was blocked by mifepristone co-administration. This study provides further evidence for the glucocorticoid regulation of serotonin biosynthesis via inhibition of TPH2 expression, and suggest that elevated glucocorticoid levels may be relevant to the etiology of psychiatric diseases, such as depression, where hypothalamic-pituitary-adrenal axis dysregulation has been documented.
Collapse
Affiliation(s)
- J A Clark
- Stroke and Neurodegeneration, Merck Research Laboratories, West Point, PA 19486, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|