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Sato T, Sugaya T, Talukder AH, Tsushima Y, Sasaki S, Uchida K, Sato T, Ikoma Y, Sakimura K, Fukuda A, Matsui K, Itoi K. Dual action of serotonin on local excitatory and inhibitory neural circuits regulating the corticotropin-releasing factor neurons in the paraventricular nucleus of the hypothalamus. J Neuroendocrinol 2023; 35:e13351. [PMID: 37901949 DOI: 10.1111/jne.13351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2022] [Revised: 10/06/2023] [Accepted: 10/10/2023] [Indexed: 10/31/2023]
Abstract
Serotonergic neurons originating from the raphe nuclei have been proposed to regulate corticotropin-releasing factor (CRF) neurons in the paraventricular nucleus of the hypothalamus (PVH). Since glutamate- and γ-aminobutyric acid (GABA)-containing neurons, constituting the hypothalamic local circuits, innervate PVH CRF neurons, we examined whether they mediate the actions of serotonin (5-hydroxytryptamine [5-HT]) on CRF neurons. Spontaneous excitatory postsynaptic currents (sEPSCs) or spontaneous inhibitory postsynaptic currents (sIPSCs) were recorded in PVH CRF neurons, under whole cell patch-clamp, using the CRF-modified yellow fluorescent protein (Venus) ΔNeo mouse. Serotonin elicited an increase in the frequency of sEPSCs in 77% of the cells and a decrease in the frequency of sIPSCs in 71% of the cells, tested in normal medium. Neither the amplitude nor decay time of sEPSC and sIPSC was affected, thus the site(s) of action of serotonin may be presynaptic. In the presence of tetrodotoxin (TTX), serotonin had no significant effects on either parameter of sEPSC or sIPSC, indicating that the effects of serotonin are action potential-dependent, and that the presynaptic interneurons are largely intact within the slice; distant neurons may exist, though, since some 20%-30% of neurons did not respond to serotonin without TTX. We next examined through what receptor subtype(s) serotonin exerts its effects on presynaptic interneurons. DOI (5-HT2A/2C agonist) mimicked the action of serotonin on the sIPSCs, and the serotonin-induced decrease in sIPSC frequency was inhibited by a selective 5-HT2C antagonist RS102221. 8-OH-DPAT (5-HT1A/7 agonist) mimicked the action of serotonin on the sEPSCs, and the serotonin-induced increase in sEPSC frequency was inhibited by a selective 5-HT7 antagonist SB269970. Thus, serotonin showed a dual action on PVH CRF neurons, by upregulating glutamatergic- and downregulating GABAergic interneurons; the former may partly be mediated by 5-HT7 receptors, whereas the latter by 5-HT2C receptors. The CRF-Venus ΔNeo mouse was useful for the electrophysiological examination.
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Affiliation(s)
- Takayuki Sato
- Laboratory of Information Biology, Graduate School of Information Sciences, Tohoku University, Sendai, Japan
| | - Takuma Sugaya
- Laboratory of Information Biology, Graduate School of Information Sciences, Tohoku University, Sendai, Japan
| | - Ashraf Hossain Talukder
- Laboratory of Information Biology, Graduate School of Information Sciences, Tohoku University, Sendai, Japan
| | - Yuki Tsushima
- Laboratory of Information Biology, Graduate School of Information Sciences, Tohoku University, Sendai, Japan
| | - Shotaro Sasaki
- Laboratory of Information Biology, Graduate School of Information Sciences, Tohoku University, Sendai, Japan
| | - Katsuya Uchida
- Laboratory of Information Biology, Graduate School of Information Sciences, Tohoku University, Sendai, Japan
| | - Tatsuya Sato
- Laboratory of Information Biology, Graduate School of Information Sciences, Tohoku University, Sendai, Japan
| | - Yoko Ikoma
- Super-Network Brain Physiology, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Kenji Sakimura
- Department of Animal Model Development, Brain Research Institute, Niigata University, Niigata, Japan
| | - Atsuo Fukuda
- Department of Physiology, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Ko Matsui
- Super-Network Brain Physiology, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Keiichi Itoi
- Laboratory of Information Biology, Graduate School of Information Sciences, Tohoku University, Sendai, Japan
- Super-Network Brain Physiology, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
- Department of Neuroendocrinology, Graduate School of Medicine, Tohoku University, Sendai, Japan
- Department of Nursing, Tohoku Fukushi University, Sendai, Japan
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Fares J, Mohamed F, Yosra Z, Oumaya H, Riadh B, Jihenne M. Influence of Antipsychotic Agents on the Sexuality of Patients Diagnosed with Schizophrenia. CURRENT THERAPEUTIC RESEARCH 2023; 99:100722. [PMID: 38021266 PMCID: PMC10654135 DOI: 10.1016/j.curtheres.2023.100722] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 10/16/2023] [Indexed: 12/01/2023]
Abstract
Background Sexuality is a natural component of human behavior. The general population has been extensively studied since the first half of the 20th century. On the other hand, regarding patients treated for schizophrenia, discussing sexual disorders was initially considered inappropriate because it was believed they should not be sexually active. Given these findings, this work proposes to study the sexuality of patients with schizophrenia. Objectives Our objectives were to assess the sexuality of patients with schizophrenia, to identify factors associated with sexual dysfunction among these patients, and to determine practitioners' attitudes toward the sexuality of our study population. Methods This is a cross-sectional study carried out in the Psychiatry Department of Kairouan (outpatient department), including 46 patients diagnosed with schizophrenia. A pre-established information sheet was completed for each patient recruited, including sociodemographic and clinical data; on the other hand, 3 scales ensured a sexual psychometric evaluation: Psychotropic-Related Sexual Dysfunction Questionnaire, Arizona Sexual Experiences Scale, and Changes in Sexual Functioning Questionnaire-Male Clinical Version. Results Concerning the evaluation of sexuality according to the scales used, sexual dysfunction according to Psychotropic-Related Sexual Dysfunction Questionnaire scores was observed in 31 patients (67.4%). According to Arizona Sexual Experiences Scale scores, 24 patients (52%) had a sexual dysfunction, and for the total score of the Changes in Sexual Functioning Questionnaire-Male Clinical Version, 27 patients (58.7%) had a sexual dysfunction. We cannot confirm the existence of a relationship between the dose of the current treatment (in chlorpromazine equivalent) used and the results of the test assessing sexuality. In addition to these results, we can deduce the existence of a statistically significant association between the antipsychotic agent used and the results of the Psychotropic-Related Sexual Dysfunction Questionnaire only. Conclusions We recommend that screening for sexual dysfunction in patients followed for schizophrenia should be systematic, regardless of the antipsychotic molecule type and dosage. In this regard, we recommend the establishment of a better therapeutic relationship between caregivers and patients with schizophrenia, based on empathy and trust, so that the latter feel comfortable enough to address the sexual dimension in general and sexual dysfunction in particular.
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Affiliation(s)
- Jaballah Fares
- Department of Psychiatry, Avicenna, Razi Hospital-Mannouba, Tunis El Manar University, Tunis, Tunisia
| | - Ferhi Mohamed
- Department of Psychiatry, Ibn el Jazzar Hospital-Kairouan, Sousse University, Sousse, Tunisia
| | - Zgueb Yosra
- Department of Psychiatry, Avicenna, Razi Hospital-Mannouba, Tunis El Manar University, Tunis, Tunisia
| | - Hazem Oumaya
- Department of Psychiatry, Taher Maamouri Hospital, Nabeul, Tunisia
| | - Bouzid Riadh
- Department of Psychiatry, Taher Maamouri Hospital, Nabeul, Tunisia
| | - Mannaii Jihenne
- Department of Psychiatry, Ibn el Jazzar Hospital-Kairouan, Sousse University, Sousse, Tunisia
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Argiolas A, Argiolas FM, Argiolas G, Melis MR. Erectile Dysfunction: Treatments, Advances and New Therapeutic Strategies. Brain Sci 2023; 13:802. [PMID: 37239274 PMCID: PMC10216368 DOI: 10.3390/brainsci13050802] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 05/08/2023] [Accepted: 05/11/2023] [Indexed: 05/28/2023] Open
Abstract
Erectile dysfunction (ED) is the inability to get and maintain an adequate penile erection for satisfactory sexual intercourse. Due to its negative impacts on men's life quality and increase during aging (40% of men between 40 and 70 years), ED has always attracted researchers of different disciplines, from urology, andrology and neuropharmacology to regenerative medicine, and vascular and prosthesis implant surgery. Locally and/or centrally acting drugs are used to treat ED, e.g., phosphodiesterase 5 inhibitors (first in the list) given orally, and phentolamine, prostaglandin E1 and papaverine injected intracavernously. Preclinical data also show that dopamine D4 receptor agonists, oxytocin and α-MSH analogues may have a role in ED treatment. However, since pro-erectile drugs are given on demand and are not always efficacious, new strategies are being tested for long lasting cures of ED. These include regenerative therapies, e.g., stem cells, plasma-enriched platelets and extracorporeal shock wave treatments to cure damaged erectile tissues. Although fascinating, these therapies are laborious, expensive and not easily reproducible. This leaves old vacuum erection devices and penile prostheses as the only way to get an artificial erection and sexual intercourse with intractable ED, with penile prosthesis used only by accurately selected patients.
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Affiliation(s)
- Antonio Argiolas
- Department of Biomedical Sciences, Section of Neuroscience and Clinical Pharmacology, University of Cagliari, 09042 Monserrato, Italy; (F.M.A.); (M.R.M.)
| | - Francesco Mario Argiolas
- Department of Biomedical Sciences, Section of Neuroscience and Clinical Pharmacology, University of Cagliari, 09042 Monserrato, Italy; (F.M.A.); (M.R.M.)
| | - Giacomo Argiolas
- General Medicine Unit, Hospital San Michele, ARNAS“G. Brotzu”, Piazzale Ricchi 1, 09100 Cagliari, Italy;
| | - Maria Rosaria Melis
- Department of Biomedical Sciences, Section of Neuroscience and Clinical Pharmacology, University of Cagliari, 09042 Monserrato, Italy; (F.M.A.); (M.R.M.)
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Melis MR, Sanna F, Argiolas A. Dopamine, Erectile Function and Male Sexual Behavior from the Past to the Present: A Review. Brain Sci 2022; 12:brainsci12070826. [PMID: 35884633 PMCID: PMC9312911 DOI: 10.3390/brainsci12070826] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 06/08/2022] [Accepted: 06/21/2022] [Indexed: 11/16/2022] Open
Abstract
Early and recent studies show that dopamine through its neuronal systems and receptor subtypes plays different roles in the control of male sexual behavior. These studies show that (i) the mesolimbic/mesocortical dopaminergic system plays a key role in the preparatory phase of sexual behavior, e.g., in sexual arousal, motivation and reward, whereas the nigrostriatal system controls the sensory-motor coordination necessary for copulation, (ii) the incertohypothalamic system is involved in the consummatory aspects of sexual behavior (penile erection and copulation), but evidence for its role in sexual motivation is also available, (iii) the pro-sexual effects of dopamine occur in concert with neural systems interconnecting the hypothalamus and preoptic area with the spinal cord, ventral tegmental area and other limbic brain areas and (iv) D2 and D4 receptors play a major role in the pro-sexual effects of dopamine. Despite some controversy, increases or decreases, respectively, of brain dopamine activity induced by drugs or that occur physiologically, usually improves or worsens, respectively, sexual activity. These findings suggest that an altered central dopaminergic tone plays a role in mental pathologies characterized by aberrant sexual behavior, and that pro-erectile D4 receptor agonists may be considered a new strategy for the treatment of erectile dysfunction in men.
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Neuregulin and Dopamine D4 Receptors Contribute Independently to Depotentiation of Schaffer Collateral LTP by Temperoammonic Path Stimulation. eNeuro 2017; 4:eN-NWR-0176-17. [PMID: 28828402 PMCID: PMC5563842 DOI: 10.1523/eneuro.0176-17.2017] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 07/14/2017] [Accepted: 08/07/2017] [Indexed: 11/21/2022] Open
Abstract
Prior studies have found that dopamine (DA), acting at D4 receptors, and neuregulin (NRG), likely acting at ErbB4 receptors, are involved in a form of depotentiation of long-term potentiation (LTP) at Schaffer collateral (SC) synapses in the hippocampus. Furthermore, DA and NRG actions are intertwined in that NRG induces DA release. We previously found that low-frequency stimulation (LFS) of temperoammonic (TA) inputs to area CA1 also depotentiates previously established SC LTP through a complex signaling pathway involving endocannabinoids, GABA, adenosine, and mitogen-activated protein kinases (MAPKs), but not glutamate. In the present studies, we found that TA-induced SC depotentiation in hippocampal slices from Sprague-Dawley albino rats also involves activation of both D4 receptors and NRG-activated ErbB receptors, but that the roles of these two modulator systems are independent with D4 receptor antagonism failing to alter chemical depotentiation by NRG1β. Furthermore, a selective D4 receptor agonist was unable to depotentiate SC LTP when administered alone, suggesting that D4 receptor activation is necessary but not sufficient for TA-induced SC depotentiation. Chemical depotentiation by NRG1β was inhibited by a Pan-ErbB antagonist and by picrotoxin (PTX), an antagonist of GABA-A receptors (GABAARs), indicating that NRG likely promotes SC depotentiation via effects on GABA and interneurons. These findings have implications for understanding the role of DA and NRG in cognitive dysfunction associated with neuropsychiatric illnesses.
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Sanna F, Contini A, Melis MR, Argiolas A. Role of dopamine D4 receptors in copulatory behavior: Studies with selective D4 agonists and antagonists in male rats. Pharmacol Biochem Behav 2015; 137:110-8. [DOI: 10.1016/j.pbb.2015.08.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2015] [Revised: 07/30/2015] [Accepted: 08/13/2015] [Indexed: 01/14/2023]
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Roberts-Crowley ML, Rittenhouse AR. Characterization of ST14A Cells for Studying Modulation of Voltage-Gated Calcium Channels. PLoS One 2015; 10:e0132469. [PMID: 26147123 PMCID: PMC4492559 DOI: 10.1371/journal.pone.0132469] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 06/15/2015] [Indexed: 11/19/2022] Open
Abstract
In medium spiny neurons (MSNs) of the striatum, dopamine D2 receptors (D2Rs) specifically inhibit the Cav1.3 subtype of L-type Ca2+ channels (LTCs). MSNs are heterogeneous in their expression of dopamine receptors making the study of D2R pathways difficult in primary neurons. Here, we employed the ST14A cell line, derived from embryonic striatum and characterized to have properties of MSNs, to study Cav1.3 current and its modulation by neurotransmitters. Round, undifferentiated ST14A cells exhibited little to no endogenous Ca2+ current while differentiated ST14A cells expressed endogenous Ca2+ current. Transfection with LTC subunits produced functional Cav1.3 current from round cells, providing a homogeneous model system compared to native MSNs for studying D2R pathways. However, neither endogenous nor recombinant Cav1.3 current was modulated by the D2R agonist quinpirole. We confirmed D2R expression in ST14A cells and also detected D1Rs, D4Rs, D5Rs, Gq, calcineurin and phospholipase A2 using RT-PCR and/or Western blot analysis. Phospholipase C β-1 (PLCβ-1) expression was not detected by Western blot analysis which may account for the lack of LTC modulation by D2Rs. These findings raise caution about the assumption that the presence of G-protein coupled receptors in cell lines indicates the presence of complete signaling cascades. However, exogenous arachidonic acid inhibited recombinant Cav1.3 current indicating that channels expressed in ST14A cells are capable of modulation since they respond to a known signaling molecule downstream of D2Rs. Thus, ST14A cells provide a MSN-like cell line for studying channel modulation and signaling pathways that do not involve activation of PLCβ-1.
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Affiliation(s)
- Mandy L. Roberts-Crowley
- Department of Physiology, Program in Neuroscience, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
| | - Ann R. Rittenhouse
- Department of Physiology, Program in Neuroscience, University of Massachusetts Medical School, Worcester, Massachusetts, United States of America
- * E-mail:
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Maegawa H, Morimoto Y, Kudo C, Hanamoto H, Boku A, Sugimura M, Kato T, Yoshida A, Niwa H. Neural mechanism underlying hyperalgesic response to orofacial pain in Parkinson's disease model rats. Neurosci Res 2015; 96:59-68. [PMID: 25637312 DOI: 10.1016/j.neures.2015.01.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Revised: 01/14/2015] [Accepted: 01/19/2015] [Indexed: 11/16/2022]
Abstract
To investigate the neural mechanism of pain originating from the orofacial region in PD patients, we used PD model rats produced by unilateral injection of 6-hydroxydopamine (6-OHDA) into the medial forebrain bundle. We investigated effects of nigrostriatal lesions on the behavioral response (face rubbing) to formalin injection into the upper lip. We also examined expression of c-Fos and phosphorylated extracellular signal-regulated kinase (pERK) in the trigeminal spinal subnucleus caudalis (Vc) and expression of c-Fos in the periaqueductal gray matter (PAG). Face rubbings following formalin injection showed a biphasic profile, with the first phase for the first 5 min and the second phase from 10 to 90 min. Rats with 6-OHDA lesions showed increased face rubbings in the second phase when formalin was injected ipsilaterally to the lesion, and c-Fos expression in the Vc increased. When formalin was injected contralaterally, face rubbings were reduced in the first phase, however, expression levels of c-Fos and pERK in the Vc were unchanged. No significant difference was found in c-Fos expression in the PAG between 6-OHDA- and saline-injected rats. These results suggest that unilateral dopamine depletion in the nigrostriatal pathway may be involved in hypersensitivity to noxious stimulation delivered to the orofacial region.
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Affiliation(s)
- Hiroharu Maegawa
- Department of Dental Anesthesiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan.
| | - Yoshinari Morimoto
- Special Patient Oral Care Unit, Kyushu University Hospital, Fukuoka, Fukuoka 812-8582, Japan
| | - Chiho Kudo
- Department of Dental Anesthesiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Hiroshi Hanamoto
- Department of Dental Anesthesiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Aiji Boku
- Department of Dental Anesthesiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Mitsutaka Sugimura
- Department of Dental Anesthesiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Takafumi Kato
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Atsushi Yoshida
- Department of Oral Anatomy and Neurobiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
| | - Hitoshi Niwa
- Department of Dental Anesthesiology, Osaka University Graduate School of Dentistry, Suita, Osaka 565-0871, Japan
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Stimulation of dopamine D4 receptors in the paraventricular nucleus of the hypothalamus of male rats induces hyperphagia: Involvement of glutamate. Physiol Behav 2014; 133:272-81. [DOI: 10.1016/j.physbeh.2014.04.040] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2014] [Accepted: 04/29/2014] [Indexed: 11/18/2022]
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Abstract
Leptin receptors (ObRs) in the forebrain and hindbrain have been independently recognized as important mediators of leptin responses. It is unclear how leptin activity in these areas is integrated. We tested whether both forebrain and hindbrain ObRs have to be activated simultaneously to change energy balance and to maintain metabolic homeostasis. Previous studies used acute leptin injections in either the third ventricle (1-5 μg) or the fourth ventricle (3-10 μg); here we used 12-day infusions of low doses of leptin in one or both ventricles (0.1 μg/24 h in third, 0.6 μg/24 h in fourth). Male Sprague Dawley rats were fitted with third and fourth ventricle cannulas, and saline or leptin was infused from Alzet pumps for 6 or 12 days. Rats that received leptin into only the third or the fourth ventricle were not different from controls that received saline in both ventricles. By contrast, rats with low-dose leptin infusions into both the third and fourth ventricle showed a dramatic 60% reduction in food intake that was reversed on day 6, a 20% weight loss that stabilized on day 6, and a 50% decrease in body fat at day 12 despite the correction of food intake. They displayed normal activity and maintained energy expenditure despite weight loss, indicating inappropriately high thermogenesis that coincided with increased signal transducer and activator of transcription 3 (STAT3) phosphorylation in the brainstem. Altogether, these findings show that with low doses of leptin, chronic activation of both hypothalamic and brainstem ObRs is required to reduce body fat.
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Affiliation(s)
- Bhavna N Desai
- Department of Physiology, Georgia Regents University, Augusta, GA 30912, USA.
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Sanna F, Succu S, Melis MR, Argiolas A. Dopamine agonist-induced penile erection and yawning: Differential role of D2-like receptor subtypes and correlation with nitric oxide production in the paraventricular nucleus of the hypothalamus of male rats. Behav Brain Res 2012; 230:355-64. [DOI: 10.1016/j.bbr.2012.02.033] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 02/11/2012] [Accepted: 02/16/2012] [Indexed: 10/28/2022]
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Hazell GG, Hindmarch CC, Pope GR, Roper JA, Lightman SL, Murphy D, O’Carroll AM, Lolait SJ. G protein-coupled receptors in the hypothalamic paraventricular and supraoptic nuclei--serpentine gateways to neuroendocrine homeostasis. Front Neuroendocrinol 2012; 33:45-66. [PMID: 21802439 PMCID: PMC3336209 DOI: 10.1016/j.yfrne.2011.07.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2011] [Revised: 06/24/2011] [Accepted: 07/06/2011] [Indexed: 12/31/2022]
Abstract
G protein-coupled receptors (GPCRs) are the largest family of transmembrane receptors in the mammalian genome. They are activated by a multitude of different ligands that elicit rapid intracellular responses to regulate cell function. Unsurprisingly, a large proportion of therapeutic agents target these receptors. The paraventricular nucleus (PVN) and supraoptic nucleus (SON) of the hypothalamus are important mediators in homeostatic control. Many modulators of PVN/SON activity, including neurotransmitters and hormones act via GPCRs--in fact over 100 non-chemosensory GPCRs have been detected in either the PVN or SON. This review provides a comprehensive summary of the expression of GPCRs within the PVN/SON, including data from recent transcriptomic studies that potentially expand the repertoire of GPCRs that may have functional roles in these hypothalamic nuclei. We also present some aspects of the regulation and known roles of GPCRs in PVN/SON, which are likely complemented by the activity of 'orphan' GPCRs.
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Affiliation(s)
| | | | | | | | | | | | | | - Stephen J. Lolait
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, Dorothy Hodgkin Building, School of Clinical Sciences, University of Bristol, Whitson Street, Bristol BS1 3NY, UK
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Abdel-Hamid IA, Andersson KE, Salonia A. Exploration of therapeutic targets for sexual dysfunctions: lessons learned from the failed stories. Expert Opin Ther Targets 2011; 15:325-40. [DOI: 10.1517/14728222.2011.551008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Melis MR, Argiolas A. Central control of penile erection: A re-visitation of the role of oxytocin and its interaction with dopamine and glutamic acid in male rats. Neurosci Biobehav Rev 2011; 35:939-55. [DOI: 10.1016/j.neubiorev.2010.10.014] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2010] [Revised: 10/08/2010] [Accepted: 10/26/2010] [Indexed: 11/28/2022]
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Rondou P, Haegeman G, Van Craenenbroeck K. The dopamine D4 receptor: biochemical and signalling properties. Cell Mol Life Sci 2010; 67:1971-86. [PMID: 20165900 PMCID: PMC11115718 DOI: 10.1007/s00018-010-0293-y] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 01/19/2010] [Accepted: 01/26/2010] [Indexed: 01/20/2023]
Abstract
Dopamine is an important neurotransmitter that regulates several key functions in the brain, such as motor output, motivation and reward, learning and memory, and endocrine regulation. Dopamine does not mediate fast synaptic transmission, but rather modulates it by triggering slow-acting effects through the activation of dopamine receptors, which belong to the G-protein-coupled receptor superfamily. Besides activating different effectors through G-protein coupling, dopamine receptors also signal through interaction with a variety of proteins, collectively termed dopamine receptor-interacting proteins. We focus on the dopamine D4 receptor, which contains an important polymorphism in its third intracellular loop. This polymorphism has been the subject of numerous studies investigating links with several brain disorders, such as attention-deficit hyperactivity disorder and schizophrenia. We provide an overview of the structure, signalling properties and regulation of dopamine D4 receptors, and briefly discuss their physiological and pathophysiological role in the brain.
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Affiliation(s)
- Pieter Rondou
- Laboratory of Eukaryotic Gene Expression and Signal Transduction (LEGEST), Ghent University (UGent), K.L. Ledeganckstraat 35, 9000 Ghent, Belgium
- Present Address: Center for Medical Genetics Ghent (CMGG), Ghent University Hospital, Medical Research Building, De Pintelaan 185, 9000 Ghent, Belgium
| | - Guy Haegeman
- Laboratory of Eukaryotic Gene Expression and Signal Transduction (LEGEST), Ghent University (UGent), K.L. Ledeganckstraat 35, 9000 Ghent, Belgium
| | - Kathleen Van Craenenbroeck
- Laboratory of Eukaryotic Gene Expression and Signal Transduction (LEGEST), Ghent University (UGent), K.L. Ledeganckstraat 35, 9000 Ghent, Belgium
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Baskerville TA, Allard J, Wayman C, Douglas AJ. Dopamineâoxytocin interactions in penile erection. Eur J Neurosci 2009; 30:2151-64. [DOI: 10.1111/j.1460-9568.2009.06999.x] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Belda X, Armario A. Dopamine D1 and D2 dopamine receptors regulate immobilization stress-induced activation of the hypothalamus-pituitary-adrenal axis. Psychopharmacology (Berl) 2009; 206:355-65. [PMID: 19621214 DOI: 10.1007/s00213-009-1613-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/04/2009] [Accepted: 07/03/2009] [Indexed: 11/30/2022]
Abstract
RATIONALE Whereas the role of most biogenic amines in the control of the hypothalamus-pituitary-adrenal (HPA) response to stress has been extensively studied, the role of dopamine has not. OBJECTIVES We studied the effect of different dopamine receptor antagonists on HPA response to a severe stressor (immobilization, IMO) in adult male Sprague-Dawley rats. RESULTS Haloperidol administration reduced adrenocorticotropin hormone and corticosterone responses to acute IMO, particularly during the post-IMO period. This effect cannot be explained by a role of dopamine to maintain a sustained activation of the HPA axis as haloperidol did not modify the response to prolonged (up to 6 h) IMO. Administration of more selective D1 and D2 receptor antagonists (SCH23390 and eticlopride, respectively) also resulted in lower and/or shorter lasting HPA response to IMO. CONCLUSIONS Dopamine, acting through both D1 and D2 receptors, exerts a stimulatory role on the activation of the HPA axis in response to a severe stressor. The finding that dopamine is involved in the maintenance of post-stress activation of the HPA axis is potentially important because the actual pathological impact of HPA activation is likely to be related to the area under the curve of plasma glucocorticoid levels, which is critically dependent on how long after stress high levels of glucocorticoid are maintained.
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Affiliation(s)
- Xavier Belda
- Institut de Neurociències and Unitat de Fisiologia Animal (Facultat de Biociències), Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
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Bitner RS, Nikkel AL, Markosyan S, Otte S, Puttfarcken P, Gopalakrishnan M. Selective α7 nicotinic acetylcholine receptor activation regulates glycogen synthase kinase3β and decreases tau phosphorylation in vivo. Brain Res 2009; 1265:65-74. [DOI: 10.1016/j.brainres.2009.01.069] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2008] [Revised: 01/23/2009] [Accepted: 01/31/2009] [Indexed: 11/27/2022]
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Abstract
Psychopharmacological studies have implicated the mesolimbic dopamine (DA) system in the mediation of cost/benefit evaluations about delay or effort-related costs associated with larger rewards. However, the role of DA in risk-based decision making remains relatively unexplored. The present study investigated the effects of systemic manipulations of DA transmission on risky choice using a probabilistic discounting task. Over discrete trials, rats chose between two levers; a press on the 'small/certain' lever always delivered one reward pellet, whereas a press on the other, 'large/risky' lever delivered four pellets, but the probability of receiving reward decreased across the four trial blocks (100, 50, 25, 12.5%). In separate groups of well-trained rats we assessed the effects of the DA releaser amphetamine, as well as receptor selective agonists and antagonists. Amphetamine consistently increased preference for the large/risky lever; an effect that was blocked or attenuated by co-administration of either D(1) (SCH23390) or D(2) (eticlopride) receptor antagonists. Blockade of either of these receptors alone induced risk aversion. Conversely, stimulation of D(1) (SKF81297) or D(2) (bromocriptine) receptors also increased risky choice. In contrast, activation of D(3) receptors with PD128,907 reduced choice of the large/risky lever. Likewise, D(3) antagonism with nafadotride potentiated the amphetamine-induced increase in risky choice. Blockade or stimulation of D(4) receptors did not reliably alter behavior. These findings indicate that DA has a critical role in mediating risk-based decision making, with increased activation of D(1) and D(2) receptors biasing choice toward larger, probabilistic rewards, whereas D(3) receptors appear to exert opposing effects on this form of decision making.
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Jackson CR, Chaurasia SS, Zhou H, Haque R, Storm DR, Iuvone PM. Essential roles of dopamine D4 receptors and the type 1 adenylyl cyclase in photic control of cyclic AMP in photoreceptor cells. J Neurochem 2009; 109:148-57. [PMID: 19166506 DOI: 10.1111/j.1471-4159.2009.05920.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Light and dopamine regulate many physiological functions in the vertebrate retina. Light exposure decreases cyclic AMP formation in photoreceptor cells. Dopamine D(4) receptor (D(4)R) activation promotes light adaptation and suppresses the light-sensitive pool of cyclic AMP in photoreceptor cells. The key signaling pathways involved in regulating cyclic AMP in photoreceptor cells have not been identified. In the present study, we show that the light- and D(4)R-signaling pathways converge on the type 1 Ca(2+)/calmodulin-stimulated adenylyl cyclase (AC1) to regulate cyclic AMP synthesis in photoreceptor cells. In addition, we present evidence that D(4)R activation tonically regulates the expression of AC1 in photoreceptors. In retinas of mice with targeted deletion of the gene (Adcy1) encoding AC1, cyclic AMP levels and Ca(2+)/calmodulin-stimulated adenylyl cyclase activity are markedly reduced, and cyclic AMP accumulation is unaffected by either light or D(4)R activation. Similarly, in mice with disruption of the gene (Drd4) encoding D(4)R, cyclic AMP levels in the dark-adapted retina are significantly lower compared to wild-type retina and are unresponsive to light. These changes in Drd4-/- mice were accompanied by significantly lower Adcy1 mRNA levels in photoreceptor cells and lower Ca(2+)/calmodulin-stimulated adenylyl cyclase activity in retinal membranes compared with wild-type controls. Reduced levels of Adcy1 mRNA were also observed in retinas of wild-type mice treated chronically with a D(4)R antagonist, L-745870. Thus, activation of D(4)R is required for normal expression of AC1 and for the regulation of its catalytic activity by light. These observations illustrate a novel mechanism for cross-talk between dopamine and photic signaling pathways regulating cyclic AMP in photoreceptor cells.
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Affiliation(s)
- Chad R Jackson
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia 30322, USA
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Heusler P, Bruins Slot L, Rauly-Lestienne I, Palmier C, Tardif S, Tourette A, Ailhaud MC, Cussac D. Activation of G proteins and extracellular signal-regulated kinase 1/2 phosphorylation via human dopamine D4.4 receptors: differential pathway-dependent potencies of receptor agonists. Naunyn Schmiedebergs Arch Pharmacol 2008; 379:87-99. [PMID: 18682919 DOI: 10.1007/s00210-008-0333-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2008] [Accepted: 06/28/2008] [Indexed: 11/30/2022]
Abstract
Agonist activity at recombinant human dopamine D4.4 receptors was compared in stably transfected CHO cells using two functional readouts: G protein activation by [35S]GTPgammaS binding and phosphorylation of extracellular signal-regulated kinase 1/2 (pERK1/2). Results with a large series of agonists reveal markedly higher relative agonist efficacy in the pERK1/2 assay compared with [35S]GTPgammaS binding, while potencies were generally higher in the latter readout. Whereas efficacies were highly correlated when comparing both tests, potencies determined using the pERK1/2 assay were neither correlated with those for G protein activation nor with binding affinities. In order to examine if these differences may be attributable to distinct assay conditions (5 min incubation for pERK1/2 compared with binding equilibrium conditions for [35S]GTPgammaS), selected compounds were tested in a modified short-duration [35S]GTPgammaS binding assay. In these experiments, potencies were generally reduced; however, compounds exhibiting comparably high potency in the pERK1/2 assay were not affected by this duration-dependent potency shift. We conclude that assay parameters such as signal amplification and incubation time have to be considered with respect to the appropriate choice of experimental approaches that best reflect agonist activity at dopamine D4 receptors in vivo.
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Affiliation(s)
- Peter Heusler
- Department of Cellular and Molecular Biology, Centre de Recherche Pierre Fabre, 17, avenue Jean Moulin, F-81106, Castres Cedex, France.
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Newman-Tancredi A, Heusler P, Martel JC, Ormière AM, Leduc N, Cussac D. Agonist and antagonist properties of antipsychotics at human dopamine D4.4 receptors: G-protein activation and K+ channel modulation in transfected cells. Int J Neuropsychopharmacol 2008; 11:293-307. [PMID: 17897483 DOI: 10.1017/s1461145707008061] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Interaction at dopamine D4 receptors may improve cognitive function, which is highly impaired in individuals with schizophrenia, but comparative studies of recent antipsychotics in cellular models of D4 receptor activation are lacking. Here, we report the in-vitro profile of over 30 ligands at recombinant hD4.4 receptors. In [35S]GTPgammaS binding experiments using membranes of CHO-hD4.4 cells, apomorphine, preclamol and the selective D4 agonists, ABT724, CP226269, Ro-10-5824 and PD168077, behaved as partial agonists (Emax 20-60% vs. dopamine), whereas L745870 and RBI257, displayed antagonist properties. The 'conventional' antipsychotic, haloperidol and the 'atypicals', clozapine and risperidone, exhibited antagonist properties, while 'third generation' compounds bifeprunox, SLV313 and F15063, acted as partial agonists (10-30%). Aripiprazole and SSR181507 slightly stimulated [35S]GTPgammaS binding at micromolar concentrations. In Xenopus laevis oocytes co-expressing hD4.4 receptors with G-protein-coupled inwardly rectifying potassium (GIRK) channels, apomorphine, preclamol, ABT724, CP226269, and PD168077 stimulated GIRK currents (Emax 70-80%). The 5-HT1A receptor ligands, WAY100635 and flibanserin, also exhibited partial agonist activity (30% and 15%, respectively). Haloperidol, clozapine, olanzapine and nemonapride did not stimulate GIRK currents, whereas aripiprazole, bifeprunox, SLV313 and F15063, but not SSR181507, exhibited partial agonism (Emax 20-35%). In-vitro responses depended on experimental conditions: increasing NaCl concentration (30 mm to 100 mm) reduced agonist efficacy in [35S]GTPgammaS binding, whereas decreasing the amount of hD4.4 cRNA injected into oocytes (from 2.0 to 0.5 ng/oocyte) reduced agonist efficacy of several compounds. These data indicate that, unlike conventional or 'atypical' antipsychotics, several 'third generation' agents display D4 receptor partial agonism that may be sufficient to influence physiological D4 receptor activity in vivo.
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Tassorelli C, Armentero MT, Greco R, Fancellu R, Sandrini G, Nappi G, Blandini F. Behavioral responses and Fos activation following painful stimuli in a rodent model of Parkinson's disease. Brain Res 2007; 1176:53-61. [PMID: 17884026 DOI: 10.1016/j.brainres.2007.08.012] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2007] [Revised: 08/06/2007] [Accepted: 08/07/2007] [Indexed: 11/21/2022]
Abstract
In Parkinson's disease (PD), the motor dysfunction caused by degeneration of the nigrostriatal pathway is often associated with alterations of pain perception. This is likely related to the role that the nigrostriatal system may play in the processing of noxious, somatosensory stimuli. To further address this issue, we used a rodent model of PD, based on the unilateral, intrastriatal injection of neurotoxin 6-hydroxydopamine (6-OHDA). We investigated the effects of the nigrostriatal lesion on behavioral responses to pain tests designed to explore different aspects of nociception, such as the formalin test and the tail flick test; we also explored modifications in the expression of Fos protein, a marker of neuronal activation, in supraspinal nuclei involved in the integration of pain perception and stress-related behavior. Rats bearing the nigrostriatal lesion showed complex alterations in pain perception, including hyperalgesic responses to the tonic, inflammatory pain elicited by formalin injection, but only when the stimulus was delivered ipsilaterally to the lesion. This phenomenon was associated with delayed responses to the phasic, thermal stimulus induced by the tail flick test. The hyperalgesic response to the formalin test was accompanied by reduced Fos expression in the paraventricular nucleus of the hypothalamus, which is part of a network (the medial pain system) that mediates motivational-affective aspects of pain. Our results confirm that a unilateral alteration of central dopaminergic transmission disrupts the neural mechanisms underlying proper integration of painful stimuli, particularly in the hemibody ipsilateral to the dopaminergic denervation.
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Affiliation(s)
- Cristina Tassorelli
- Laboratory of Pathophysiology of Integrative Autonomic Systems, Neurological Institute C Mondino, Pavia, Italy
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Khan AM, Ponzio TA, Sanchez-Watts G, Stanley BG, Hatton GI, Watts AG. Catecholaminergic control of mitogen-activated protein kinase signaling in paraventricular neuroendocrine neurons in vivo and in vitro: a proposed role during glycemic challenges. J Neurosci 2007; 27:7344-60. [PMID: 17611287 PMCID: PMC6794600 DOI: 10.1523/jneurosci.0873-07.2007] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2007] [Revised: 05/30/2007] [Accepted: 05/31/2007] [Indexed: 11/21/2022] Open
Abstract
Paraventricular hypothalamic (PVH) corticotropin-releasing hormone (CRH) neuroendocrine neurons mount neurosecretory and transcriptional responses to glycemic challenges [intravenous 2-deoxyglucose (2-DG) or insulin]. Although these responses require signals from intact afferents originating from hindbrain CA (catecholaminergic) neurons, the identity of these signals and the mechanisms by which they are transduced by PVH neurons during glycemic challenge remain unclear. Here, we tested whether the prototypical catecholamine, norepinephrine (NE), can reproduce PVH neuroendocrine responses to glycemic challenge. Because these responses include phosphorylation of p44/42 mitogen-activated protein (MAP) kinases [extracellular signal-regulated kinases 1/2 (ERK1/2)], we also determined whether NE activates ERK1/2 in PVH neurons and, if so, by what mechanism. We show that systemic insulin and 2-DG, and PVH-targeted NE microinjections, rapidly elevated PVH phospho-ERK1/2 levels. NE increased Crh and c-fos expression, together with circulating ACTH/corticosterone. However, because injections also increased c-Fos mRNA in other brain regions, we used hypothalamic slices maintained in vitro to clarify whether NE activates PVH neurons without contribution of inputs from distal regions. In slices, bath-applied NE triggered robust phospho-ERK1/2 immunoreactivity in PVH (including CRH) neurons, which attenuated markedly in the presence of the alpha1 adrenoceptor antagonist, prazosin, or the MAP kinase kinase (MEK) inhibitor, U0126 (1,4-diamino-2,3-dicyano-1,4-bis[2-aminophenylthio]butadiene). Therefore, at a systems level, local PVH delivery of NE is sufficient to account for hindbrain activation of CRH neuroendocrine neurons during glycemic challenge. At a cellular level, these data provide the first demonstration that MAP kinase signaling cascades (MEK-->ERK) are intracellular transducers of noradrenergic signals in CRH neurons, and implicate this transduction mechanism as an important component of central neuroendocrine responses during glycemic challenge.
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Affiliation(s)
- Arshad M Khan
- Neuroscience Research Institute and Department of Biological Sciences, University of Southern California, Los Angeles, California 90089-2520, USA.
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Abstract
PURPOSE OF REVIEW Sexual dysfunctions have been described as being common in schizophrenia patients. The pathophysiology behind their development remains unclear. They can be secondary to the disease itself or an adverse event of antipsychotic medication. Therapeutic interventions are also not well studied. RECENT FINDINGS Earlier work has suggested that second-generation antipsychotics bear fewer risks for developing sexual dysfunction because of a lower propensity to elevate prolactin levels, although the latter does not apply to amisulpride and risperidone. Only a few controlled trials with larger patient samples have been performed in the past. SUMMARY The review covers studies published from March 2005 to June 2006 focusing on sexual dysfunctions in schizophrenia patients, as well as their possible causes. Treatment options and the impact of sexual dysfunction on quality of life are also covered. The reviewed papers show no clear consistency regarding potential advantages of one drug over another. Many trials suffer from small sample sizes. The field badly needs more and larger studies on this topic.
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Affiliation(s)
- Peter Malik
- Department of Biological Psychiatry, Medical University Innsbruck, Austria.
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Succu S, Sanna F, Melis T, Boi A, Argiolas A, Melis MR. Stimulation of dopamine receptors in the paraventricular nucleus of the hypothalamus of male rats induces penile erection and increases extra-cellular dopamine in the nucleus accumbens: Involvement of central oxytocin. Neuropharmacology 2007; 52:1034-43. [PMID: 17164075 DOI: 10.1016/j.neuropharm.2006.10.019] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2006] [Revised: 10/29/2006] [Accepted: 10/31/2006] [Indexed: 11/21/2022]
Abstract
The effect of a pro-erectile dose of apomorphine, a mixed dopamine receptor agonist, and of PD-168077 (N-[4-(2-cyanophenyl)piperazin-1-ylmethyl]-3-methylbenzamide maleate), a selective dopamine D4 receptor agonist, injected into the paraventricular nucleus of the hypothalamus on the concentration of extra-cellular dopamine and its main metabolite 3,4-dihydroxyphenylacetic acid (DOPAC) in the dialysate from the nucleus accumbens was studied in male rats. As expected, apomorphine (0.1microg) and PD-168077 (0.1microg) induced penile erection episodes, which occurred concomitantly to an increase in extra-cellular dopamine and DOPAC concentration in the dialysate from the shell of the nucleus accumbens, as measured by intracerebral microdialysis. When induced by apomorphine, these effects were reduced by 80% by raclopride, a selective D2/D3 receptor antagonist (1microg) and only by 40-45% by L-745,870 (1microg), a selective dopamine D4 receptor antagonist. When induced by PD-168077, these effects were reduced by more than 80% by L-745,870 (1microg), but only by 35-40% by raclopride. Irrespective of the dopamine agonist used to induce penile erection, the pro-erectile effect and the concomitant increase in dopamine and DOPAC concentration in the nucleus accumbens dialysate were almost completely abolished by d(CH(2))(5)Tyr(Me)(2)-Orn(8)-vasotocin(1microg), a potent oxytocin receptor antagonist, given into the lateral ventricles. The present results suggest that stimulation of dopamine receptors (mainly of the D2 to D4 subtype) in the paraventricular nucleus induces the release of oxytocin in brain areas that influence the activity of mesolimbic dopaminergic neurons mediating the appetitive and reinforcing effects of sexual activity. This provides evidence for a role of oxytocin in neural circuits that integrate the activity of neural pathways controlling the consummatory aspects of sexual behaviour (e.g., penile erection) with those controlling sexual motivation and sexual arousal.
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Affiliation(s)
- Salvatora Succu
- Bernard B Brodie Department of Neuroscience, Centre of Excellence for The Neurobiology of Addictions, University of Cagliari, S.P. Sestu-Monserrato, Km 0.700, 09042 Monserrato, CA, Italy
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Melis MR, Succu S, Sanna F, Melis T, Mascia MS, Enguehard-Gueiffier C, Hubner H, Gmeiner P, Gueiffier A, Argiolas A. PIP3EA and PD-168077, two selective dopamine D4 receptor agonists, induce penile erection in male rats: site and mechanism of action in the brain. Eur J Neurosci 2006; 24:2021-30. [PMID: 17067298 DOI: 10.1111/j.1460-9568.2006.05043.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PIP3EA (2-[4-(2-methoxyphenyl)piperazin-1-yl-methyl]imidazo[1,2-a]pyridine) and PD-168077 (N-[4-2-cyanophenylpiperazin-1-ylmethyl]-3-methylbenzamide maleate), two selective dopamine D4 agonists, administered systemically, intracerebroventricularly or into the paraventricular nucleus of the hypothalamus induce penile erection in male Sprague-Dawley rats. A U-inverted dose-response curve was found with either compound when given subcutaneously (1-100 microg/kg) or intracerebroventricularly (0.1-20 microg/rat), but not into the paraventricular nucleus (10-200 ng/rat). The pro-erectile effect of PIP3EA and of PD-168077 occurs concomitantly with an increased nitric oxide (NO) production in the paraventricular nucleus, as measured by the increased concentration of nitrites and nitrates found in the dialysate obtained from the paraventricular nucleus by intracerebral microdialysis. These effects of PIP3EA and PD-168077 were reduced by L-745,870 (3-[4-(4-chlorophenyl)piperazin-1-ylmethyl]-1H-pyrrolo[2,3-b]pyridine trihydrochloride), a selective dopamine D4 receptors antagonist, by omega-conotoxin, a blocker of voltage-dependent Ca2+ channels of the N-type, by S-methyl-thiocitrulline, a neuronal nitric oxide synthase inhibitor, and by d(CH2)5Tyr(Me)2-Orn8-vasotocin, an oxytocin receptor antagonist, given into the lateral ventricles, but not into the paraventricular nucleus. Comparison of the dose-response curves of PIP3EA and PD-168077 revealed that PIP3EA is as potent as PD-168077 when given into the paraventricular nucleus, but more potent when given systemically. However, both compounds are less efficacious (e.g. induce a lower number of penile erection episodes) than apomorphine, a classical mixed dopamine receptor agonist, irrespective of the route of administration. These results confirm previous findings showing that central D4 receptors mediate penile erection and show that dopamine D4 receptor agonists act in the paraventricular nucleus to facilitate penile erection by increasing central oxytocinergic neurotransmission.
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Affiliation(s)
- Maria Rosaria Melis
- Bernard B. Brodie Department of Neuroscience, Centre of Excellence for the Neurobiology of Addictions, University of Cagliari, Italy.
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