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Mercier C, Rollason V, Eshmawey M, Mendes A, Frisoni GB. The treatment of behavioural and psychological symptoms in dementia: pragmatic recommendations. Psychogeriatrics 2024; 24:968-982. [PMID: 38638077 DOI: 10.1111/psyg.13116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Revised: 02/20/2024] [Accepted: 03/19/2024] [Indexed: 04/20/2024]
Abstract
Behavioural and psychological symptoms of dementia (BPSD) are a clinical challenge for the lack of a sound taxonomy, frequent presentation with comorbid BPSD, lack of specific pharmacologic interventions, poor base of methodologically sound evidence with randomized clinical trials, contamination from the treatment of behavioural disturbances of young and adult psychiatric conditions, and small efficacy window of psychotropic drugs. We present here a treatment workflow based on a concept-driven literature review based on the notions that (i) the aetiology of BPSD can be mainly neurobiological (so-called 'primary' symptoms) or mainly environmental and functional ('secondary' symptoms) and that this drives treatment; (ii) the clinical efficacy of psychotropic drugs is driven by their specific profile of receptor affinity; (iii) drug treatment should follow the rules of 'start low-go slow, prescribe and revise'. This article argues in support of the distinction between primary and secondary BPSD, as well as their characteristics, which until now have been just sketchily described in the literature. It also offers comprehensive and pragmatic clinician-oriented recommendations for the treatment of BPSD.
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Affiliation(s)
- Camille Mercier
- Laboratory of Neuroimaging of Aging (LANVIE), University of Geneva, Geneva, Switzerland
- Memory Center, Department of Rehabilitation and Geriatrics, University Hospitals of Geneva, Geneva, Switzerland
| | - Victoria Rollason
- Department of Acute Medicine, Clinical Pharmacology and Toxicology Service, University Hospitals of Geneva, Geneva, Switzerland
| | - Mohamed Eshmawey
- Department of Psychiatry, Geriatric Psychiatry Service, University Hospitals of Geneva, Geneva, Switzerland
| | - Aline Mendes
- Geriatrics and Rehabilitation Department, Department of Rehabilitation and Geriatrics, University Hospitals of Geneva and University of Geneva, Geneva, Switzerland
| | - Giovanni B Frisoni
- Laboratory of Neuroimaging of Aging (LANVIE), University of Geneva, Geneva, Switzerland
- Memory Center, Department of Rehabilitation and Geriatrics, University Hospitals of Geneva, Geneva, Switzerland
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Huang Z, Wu J, Guan Y, Wei Y, Xie F, Shen Y. PET/CT study of dopamine transporter (DAT) binding with the triple reuptake inhibitor toludesvenlafaxine in rats and humans. Eur J Nucl Med Mol Imaging 2024; 51:2638-2648. [PMID: 38587645 DOI: 10.1007/s00259-024-06700-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 03/19/2024] [Indexed: 04/09/2024]
Abstract
PURPOSE Toludesvenlafaxine is a recently developed antidepressant that belongs to the triple reuptake inhibitor class. Despite the in vitro evidence that toludesvenlafaxine inhibits the reuptake of serotonin (5-HT), norepinephrine (NE) and dopamine (DA), there is no in vivo evidence that toludesvenlafaxine binds to DAT and increases DA level, a mechanism thought to contribute to its favorable clinical performance. METHODS Positron emission tomography/computed tomography (PET/CT) was used to examine the DAT binding capacity in healthy rats and human subjects and microdialysis was used to examine the striatal DA level in rats. [18F]FECNT and [11C]CFT were used as PET/CT radioactive tracer for rat and human studies, respectively. RESULTS In rats, 9 mg/kg of toludesvenlafaxine hydrochloride (i.v.) followed by an infusion of 3 mg/kg via minipump led to the binding rate to striatum DAT at 3.7 - 32.41% and to hypothalamus DAT at 5.91 - 17.52% during the 45 min scanning period. 32 mg/kg oral administration with toludesvenlafaxine hydrochloride significantly increased the striatal DA level with the AUC0 - 180 min increased by 63.9%. In healthy volunteers, 160 mg daily toludesvenlafaxine hydrochloride sustained-release tablets for 4 days led to an average occupancy rates of DAT at 8.04% ± 7.75% and 8.09% ± 7.00%, respectively, in basal ganglion 6 h and 10 h postdose. CONCLUSION These results represent the first to confirm the binding of toludesvenlafaxine to DAT in both rats and humans using PET/CT, and its elevation of brain DA level, which may help understand the unique pharmacological and functional effects of triple reuptake inhibitors such as toludesvenlafaxine. CLINICALTRIALS GOV IDENTIFIERS NCT05905120. Registered 14 June 2023. (retrospectively registered).
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Affiliation(s)
- Zhiwei Huang
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Junhao Wu
- Department of Nuclear Medicine & PET Center, Huashan Hospital, Fudan University, Shanghai, China
| | - Yihui Guan
- Department of Nuclear Medicine & PET Center, Huashan Hospital, Fudan University, Shanghai, China
| | - Yumei Wei
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Fang Xie
- Department of Nuclear Medicine & PET Center, Huashan Hospital, Fudan University, Shanghai, China.
| | - Yifeng Shen
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
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3
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Szukiewicz D. Current Insights in Prolactin Signaling and Ovulatory Function. Int J Mol Sci 2024; 25:1976. [PMID: 38396659 PMCID: PMC10889014 DOI: 10.3390/ijms25041976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 01/31/2024] [Accepted: 02/03/2024] [Indexed: 02/25/2024] Open
Abstract
Prolactin (PRL) is a pleiotropic hormone released from lactotrophic cells of the anterior pituitary gland that also originates from extrapituitary sources and plays an important role in regulating lactation in mammals, as well as other actions. Acting in an endocrine and paracrine/autocrine manner, PRL regulates the hypothalamic-pituitary-ovarian axis, thus influencing the maturation of ovarian follicles and ovulation. This review provides a detailed discussion of the current knowledge on the role of PRL in the context of ovulation and ovulatory disorders, particularly with regard to hyperprolactinemia, which is one of the most common causes of infertility in women. Much attention has been given to the PRL structure and the PRL receptor (PRLR), as well as the diverse functions of PRLR signaling under normal and pathological conditions. The hormonal regulation of the menstrual cycle in connection with folliculogenesis and ovulation, as well as the current classifications of ovulation disorders, are also described. Finally, the state of knowledge regarding the importance of TIDA (tuberoinfundibular dopamine), KNDγ (kisspeptin/neurokinin B/dynorphin), and GnRH (gonadotropin-releasing hormone) neurons in PRL- and kisspeptin (KP)-dependent regulation of the hypothalamic-pituitary-gonadal (HPG) axis in women is reviewed. Based on this review, a rationale for influencing PRL signaling pathways in therapeutic activities accompanying ovulation disorders is presented.
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Affiliation(s)
- Dariusz Szukiewicz
- Department of Biophysics, Physiology & Pathophysiology, Faculty of Health Sciences, Medical University of Warsaw, 02-004 Warsaw, Poland
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Giatti S, Diviccaro S, Cioffi L, Cosimo Melcangi R. Post-Finasteride Syndrome And Post-Ssri Sexual Dysfunction: Two Clinical Conditions Apparently Distant, But Very Close. Front Neuroendocrinol 2024; 72:101114. [PMID: 37993021 DOI: 10.1016/j.yfrne.2023.101114] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 10/31/2023] [Accepted: 11/19/2023] [Indexed: 11/24/2023]
Abstract
Post-finasteride syndrome and post-SSRI sexual dysfunction, are two poorly explored clinical conditions in which men treated for androgenetic alopecia with finasteride or for depression with SSRI antidepressants show persistent side effects despite drug suspension (e.g., sexual dysfunction, psychological complaints, sleep disorders). Because of some similarities in the symptoms, common pathological mechanisms are proposed here. Indeed, as discussed, clinical studies and preclinical data obtained so far suggest an important role for brain modulators (i.e., neuroactive steroids), neurotransmitters (i.e., serotonin, and cathecolamines), and gut microbiota in the context of the gut-brain axis. In particular, the observed interconnections of these signals in these two clinical conditions may suggest similar etiopathogenetic mechanisms, such as the involvement of the enzyme converting norepinephrine into epinephrine (i.e., phenylethanolamine N-methyltransferase). However, despite the current efforts, more work is still needed to advance the understanding of these clinical conditions in terms of diagnostic markers and therapeutic strategies.
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Affiliation(s)
- Silvia Giatti
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy
| | - Silvia Diviccaro
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy
| | - Lucia Cioffi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy
| | - Roberto Cosimo Melcangi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milano, Italy.
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Fiala L, Lenz J, Havelka P, Vetvicka V. Delayed ejaculation in men with depressive disorders. Andrologia 2022; 54:e14412. [PMID: 35243671 DOI: 10.1111/and.14412] [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: 01/17/2022] [Revised: 02/16/2022] [Accepted: 02/25/2022] [Indexed: 11/30/2022] Open
Abstract
Delayed ejaculation belongs to the group of sexual disorders in men. The causes of delayed ejaculation or anejaculation are not exactly known. It is assumed that it can be caused by psychogenic or organic influences or their combinations. One of the causes of delayed ejaculation may be elevated prolactin levels, which may be increased by psychosocial stress, pituitary disorders or also treatment with selective serotonin reuptake inhibitors in the treatment of depression. We tested a selected group of 50 men who were diagnosed with a depressive disorder and whose antidepressant treatment lasted for at least 24 weeks. These patients reported long-term delayed ejaculation or, in some cases, anejaculation as comorbidity. The results showed significant Spearman's correlation between elevated prolactin levels and intravaginal ejaculation latency values (R = 0.45), as well as between Beck's Depression-II inventory and intravaginal ejaculation latency and latency values (R = 0.48).
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Affiliation(s)
- Ludek Fiala
- Department of Sexology, Psychiatric Clinic, Faculty of Medicine, Charles University, Pilsen, Czech Republic.,First Faculty of Medicine, Institute of Sexology, Charles University, Prague, Czech Republic
| | - Jiri Lenz
- Department of Pathology, Znojmo Hospital, Znojmo, Czech Republic.,Department of Anatomy, Histology and Embryology, Faculty of Veterinary Medicine, University of Veterinary and Pharmaceutical Sciences Brno, Brno, Czech Republic
| | - Pavel Havelka
- Department of Gynecology and Sexology, Bata Hospital, Zlin, Czech Republic
| | - Vaclav Vetvicka
- Department of Pathology, University of Louisville, Louisville, Kentucky, USA
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Georgescu T, Swart JM, Grattan DR, Brown RSE. The Prolactin Family of Hormones as Regulators of Maternal Mood and Behavior. Front Glob Womens Health 2021; 2:767467. [PMID: 34927138 PMCID: PMC8673487 DOI: 10.3389/fgwh.2021.767467] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Accepted: 11/01/2021] [Indexed: 12/30/2022] Open
Abstract
Transition into motherhood involves profound physiological and behavioral adaptations that ensure the healthy development of offspring while maintaining maternal health. Dynamic fluctuations in key hormones during pregnancy and lactation induce these maternal adaptations by acting on neural circuits in the brain. Amongst these hormonal changes, lactogenic hormones (e.g., prolactin and its pregnancy-specific homolog, placental lactogen) are important regulators of these processes, and their receptors are located in key brain regions controlling emotional behaviors and maternal responses. With pregnancy and lactation also being associated with a marked elevation in the risk of developing mood disorders, it is important to understand how hormones are normally regulating mood and behavior during this time. It seems likely that pathological changes in mood could result from aberrant expression of these hormone-induced behavioral responses. Maternal mental health problems during pregnancy and the postpartum period represent a major barrier in developing healthy mother-infant interactions which are crucial for the child's development. In this review, we will examine the role lactogenic hormones play in driving a range of specific maternal behaviors, including motivation, protectiveness, and mother-pup interactions. Understanding how these hormones collectively act in a mother's brain to promote nurturing behaviors toward offspring will ultimately assist in treatment development and contribute to safeguarding a successful pregnancy.
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Affiliation(s)
- Teodora Georgescu
- Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - Judith M. Swart
- Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
| | - David R. Grattan
- Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand
- Department of Anatomy, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, Auckland, New Zealand
| | - Rosemary S. E. Brown
- Centre for Neuroendocrinology, University of Otago, Dunedin, New Zealand
- Department of Physiology, School of Biomedical Sciences, University of Otago, Dunedin, New Zealand
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Zhu H, Wang W, Sha C, Guo W, Li C, Zhao F, Wang H, Jiang W, Tian J. Pharmacological Characterization of Toludesvenlafaxine as a Triple Reuptake Inhibitor. Front Pharmacol 2021; 12:741794. [PMID: 34594228 PMCID: PMC8476831 DOI: 10.3389/fphar.2021.741794] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 08/30/2021] [Indexed: 11/13/2022] Open
Abstract
Toludesvenlafaxine hydrochloride dihydrate is a novel chemical entity and a potential triple monoamine reuptake inhibitor. This study characterized the in vitro triple reuptake inhibition activity, antidepressant-like activity in animals, and pharmacokinetic profiles in rats of toludesvenlafaxine. Binding affinity was determined using human serotonin transporter (SERT) protein, norepinephrine transporter (NET) protein and dopamine transporter (DAT) protein, and the reuptake inhibition was determined using Chinese hamster ovary cells expressing human SERT, NET and DAT. The antidepressant-like activity was examined in rat chronic unpredictable mild stress model and olfactory bulbectomized model. In rats, the tissue distribution and pharmacokinetic parameters were determined. Toludesvenlafaxine had high binding affinity on SERT, NET and DAT, and significantly inhibited the reuptake of serotonin (IC50 = 31.4 ± 0.4 nM), norepinephrine (IC50 = 586.7 ± 83.6 nM) and dopamine (IC50 = 733.2 ± 10.3 nM) in vitro. Toludesvenlafaxine demonstrated significant antidepressant-like effects in rat models at 8-16 mg/kg. In addition, toludesvenlafaxine significantly reduced serum corticosterone and significantly increased testosterone levels in rats. Toludesvenlafaxine was quickly absorbed and converted to O-desvenlafaxine (ODV) after oral administration, both of which were selectively distributed into the hypothalamus with high concentration. Plasma ODV exposure was proportionally related to the doses after oral dosing. These results suggest that toludesvenlafaxine is a triple reuptake inhibitor with relatively fast-acting antidepressant-like activity and good therapeutic profile including improvement of anhedonia and sexual function.
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Affiliation(s)
- Haibo Zhu
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, China
| | - Wenyan Wang
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, China
| | - Chunjie Sha
- State Key Laboratory of Long-acting and Targeting Drug Delivery System, R&D of Luye Pharmaceutical Group, Yantai, China
| | - Wei Guo
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, China
| | - Chunmei Li
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, China
| | - Fengjuan Zhao
- State Key Laboratory of Long-acting and Targeting Drug Delivery System, R&D of Luye Pharmaceutical Group, Yantai, China
| | - Hongbo Wang
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, China
| | - Wanglin Jiang
- State Key Laboratory of Long-acting and Targeting Drug Delivery System, R&D of Luye Pharmaceutical Group, Yantai, China
| | - Jingwei Tian
- School of Pharmacy, Key Laboratory of Molecular Pharmacology and Drug Evaluation, Ministry of Education, Collaborative Innovation Center of Advanced Drug Delivery System and Biotech Drugs in Universities of Shandong, Yantai University, Yantai, China.,State Key Laboratory of Long-acting and Targeting Drug Delivery System, R&D of Luye Pharmaceutical Group, Yantai, China
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8
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Rahban R, Rehfeld A, Schiffer C, Brenker C, Egeberg Palme DL, Wang T, Lorenz J, Almstrup K, Skakkebaek NE, Strünker T, Nef S. The antidepressant Sertraline inhibits CatSper Ca2+ channels in human sperm. Hum Reprod 2021; 36:2638-2648. [PMID: 34486673 PMCID: PMC8450872 DOI: 10.1093/humrep/deab190] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Revised: 06/01/2021] [Indexed: 12/12/2022] Open
Abstract
STUDY QUESTION Do selective serotonin reuptake inhibitor (SSRI) antidepressants affect the function of human sperm? SUMMARY ANSWER The SSRI antidepressant Sertraline (e.g. Zoloft) inhibits the sperm-specific Ca2+ channel CatSper and affects human sperm function in vitro. WHAT IS KNOWN ALREADY In human sperm, CatSper translates changes of the chemical microenvironment into changes of the intracellular Ca2+ concentration ([Ca2+]i) and swimming behavior. CatSper is promiscuously activated by oviductal ligands, but also by synthetic chemicals that might disturb the fertilization process. It is well known that SSRIs have off-target actions on Ca2+, Na+ and K+ channels in somatic cells. Whether SSRIs affect the activity of CatSper is, however, unknown. STUDY DESIGN, SIZE, DURATION We studied the action of the seven drugs belonging to the most commonly prescribed class of antidepressants, SSRIs, on resting [Ca2+]i and Ca2+ influx via CatSper in human sperm. The SSRI Sertraline was selected for in-depth analysis of its action on steroid-, prostaglandin-, pH- and voltage-activation of human CatSper. Moreover, the action of Sertraline on sperm acrosomal exocytosis and penetration into viscous media was evaluated. PARTICIPANTS/MATERIALS, SETTING, METHODS The activity of CatSper was investigated in sperm of healthy volunteers, using kinetic Ca2+ fluorimetry and patch-clamp recordings. Acrosomal exocytosis was investigated using Pisum sativum agglutinin and image cytometry. Sperm penetration in viscous media was evaluated using the Kremer test. MAIN RESULTS AND THE ROLE OF CHANCE Several SSRIs affected [Ca2+]i and attenuated ligand-induced Ca2+ influx via CatSper. In particular, the SSRI Sertraline almost completely suppressed Ca2+ influx via CatSper. Remarkably, the drug was about four-fold more potent to suppress prostaglandin- versus steroid-induced Ca2+ influx. Sertraline also suppressed alkaline- and voltage-activation of CatSper, indicating that the drug directly inhibits the channel. Finally, Sertraline impaired ligand-induced acrosome reaction and sperm penetration into viscous media. LIMITATIONS, REASONS FOR CAUTION This is an in vitro study. Future studies have to assess the physiological relevance in vivo. WIDER IMPLICATIONS OF THE FINDINGS The off-target action of Sertraline on CatSper in human sperm might impair the fertilization process. In a research setting, Sertraline may be used to selectively inhibit prostaglandin-induced Ca2+ influx. STUDY FUNDING/COMPETING INTEREST(S) This work was supported by the Swiss Centre for Applied Human Toxicology (SCAHT), the Département de l’Instruction Publique of the State of Geneva, the German Research Foundation (CRU326), the Interdisciplinary Center for Clinical Research, Münster (IZKF; Str/014/21), the Innovation Fund Denmark (grant numbers 14-2013-4) and the EDMaRC research grant from the Kirsten and Freddy Johansen’s Foundation. The authors declare that no conflict of interest could be perceived as prejudicing the impartiality of the research reported. TRIAL REGISTRATION NUMBER NA.
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Affiliation(s)
- Rita Rahban
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland.,Swiss Centre for Applied Human Toxicology, Basel, Switzerland
| | - Anders Rehfeld
- Department of Growth and Reproduction, University of Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Christian Schiffer
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
| | - Christoph Brenker
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
| | | | - Tao Wang
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany.,Institute of Life Science and School of Life Science, Nanchang University, Nanchang, Jiangxi, PR China
| | - Johannes Lorenz
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
| | - Kristian Almstrup
- Department of Growth and Reproduction, University of Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Niels E Skakkebaek
- Department of Growth and Reproduction, University of Copenhagen, Rigshospitalet, Copenhagen, Denmark
| | - Timo Strünker
- Centre of Reproductive Medicine and Andrology, University Hospital Münster, University of Münster, Münster, Germany
| | - Serge Nef
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland.,Swiss Centre for Applied Human Toxicology, Basel, Switzerland
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Ammari R, Broberger C. Pre- and post-synaptic modulation by GABA B receptors of rat neuroendocrine dopamine neurones. J Neuroendocrinol 2020; 32:e12881. [PMID: 32803906 DOI: 10.1111/jne.12881] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 05/22/2020] [Accepted: 06/05/2020] [Indexed: 12/17/2022]
Abstract
The secretion of prolactin from the pituitary is negatively controlled by tuberoinfundibular dopamine (TIDA) neurones. The electrical properties of TIDA cells have recently been identified as a modulatory target of neurotransmitters and hormones in the lactotrophic axis. The role of the GABAB receptor in this control has received little attention, yet is of particular interest because it may act as a TIDA neurone autoreceptor. Here, this issue was explored in a spontaneously active rat TIDA in vitro slice preparation using whole-cell recordings. Application of the GABAB receptor agonist, baclofen, dose-dependently slowed down or abolished the network oscillations typical of this preparation. Pharmacological manipulations identify the underlying mechanism as an outward current mediated by G-protein-coupled inwardly rectifying K+ -like channels. In addition to this postsynaptic modulation, we describe a presynaptic modulation where GABAB receptors restrain the release of glutamate and GABA onto TIDA neurones. Our data identify both pre- and postsynaptic modulation of TIDA neurones by GABAB receptors that may play a role in the neuronal network control of pituitary prolactin secretion and lactation.
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Affiliation(s)
- Rachida Ammari
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Christian Broberger
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
- Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden
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10
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Zhuo C, Ji F, Tian H, Wang L, Jia F, Jiang D, Chen C, Zhou C, Lin X, Zhu J. Transient effects of multi-infusion ketamine augmentation on treatment-resistant depressive symptoms in patients with treatment-resistant bipolar depression - An open-label three-week pilot study. Brain Behav 2020; 10:e01674. [PMID: 32621379 PMCID: PMC7428494 DOI: 10.1002/brb3.1674] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Revised: 04/29/2020] [Accepted: 05/08/2020] [Indexed: 12/30/2022] Open
Abstract
INTRODUCTION While the psychiatric benefits of ketamine have been verified through clinical trials, there is limited information about ketamine augmentation in patients with treatment-resistant bipolar depression (TRBPD). Hence, in the present study, we investigate the therapeutic efficacy and functional brain alterations associated with multi-infusion ketamine augmentation in patients with TRBPD. METHODS The present three-week study included 38 patients with TRBPD, all of whom received a series of nine ketamine injections over the study period. The Hamilton Depression Rating Scale (HAMD) was used to assess the effects of multi-infusion ketamine combined with mood stabilizers. Brain function was evaluated by global functional connectivity density (gFCD). RESULTS Adjunctive treatment with multiple infusions of ketamine, when combined with a mood stabilizer, could effectively alleviate depressive symptoms for one week, yet the symptoms began to relapse during the second week. Functional brain alterations were detected via gFCD. Specifically, gFCD reductions were mainly found in the bilateral insula, right caudate nucleus, and bilateral inferior frontal gyrus, while increased gFCD was mainly located in the bilateral postcentral gyrus, subgenual anterior cingulate cortex, bilateral thalamus, and cerebellum. Although gFCD alterations were sustained for up to three weeks after the first ketamine infusion, the antidepressant effects of ketamine augmentation sharply declined from the end of the second week of treatment. CONCLUSIONS Multi-infusion ketamine augmentation can rapidly alleviate depressive symptoms in patients with TRBPD. The clinical effects were primarily visible in the first week after treatment and partially sustained for two weeks; however, the therapeutic effects and related functional brain alterations sharply decreased from the end of the second week. Based on these findings, we demonstrated that the clinical efficacy and functional brain alterations induced by ketamine augmentation are transient.
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Affiliation(s)
- Chuanjun Zhuo
- Department of Psychiatry, School of Mental Health, Jining Medical University, Jining, China.,Department of Psychiatry and Imaging-Genetics and Co-morbidity (PNGC-Lab), Tianjin Anding Hospital, Tianjin Mental Health Center, Mental Health Teaching Hospital, Tianjin Medical University, Tianjin, China.,Department of Psychiatry Wenzhou Seventh People's Hospital, Wenzhou, China
| | - Feng Ji
- Department of Psychiatry, School of Mental Health, Jining Medical University, Jining, China
| | - Hongjun Tian
- Department of Psychiatry and Imaging-Genetics and Co-morbidity (PNGC-Lab), Tianjin Anding Hospital, Tianjin Mental Health Center, Mental Health Teaching Hospital, Tianjin Medical University, Tianjin, China
| | - Lina Wang
- Department of Psychiatry and Imaging-Genetics and Co-morbidity (PNGC-Lab), Tianjin Anding Hospital, Tianjin Mental Health Center, Mental Health Teaching Hospital, Tianjin Medical University, Tianjin, China
| | - Feng Jia
- Department of Psychiatry and Imaging-Genetics and Co-morbidity (PNGC-Lab), Tianjin Anding Hospital, Tianjin Mental Health Center, Mental Health Teaching Hospital, Tianjin Medical University, Tianjin, China
| | - Deguo Jiang
- Department of Psychiatry Wenzhou Seventh People's Hospital, Wenzhou, China
| | - Ce Chen
- Department of Psychiatry Wenzhou Seventh People's Hospital, Wenzhou, China
| | - Chunhua Zhou
- Department of Pharmacy, First Hospital of Hebei Medical University, Shijiazhuang, China
| | - Xiaodong Lin
- Department of Psychiatry Wenzhou Seventh People's Hospital, Wenzhou, China
| | - Jingjing Zhu
- Department of Psychiatry Wenzhou Seventh People's Hospital, Wenzhou, China
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11
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Mörkl S, Seltenreich D, Letmaier M, Bengesser S, Wurm W, Grohmann R, Bleich S, Toto S, Stübner S, Butler MI, Kasper S. Extrapyramidal reactions following treatment with antidepressants: Results of the AMSP multinational drug surveillance programme. World J Biol Psychiatry 2020; 21:308-316. [PMID: 31347932 DOI: 10.1080/15622975.2019.1648871] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Objectives: Extrapyramidal symptoms (EPS) are a common adverse effect of antipsychotics. However, there are case reports describing EPS following treatment with antidepressants. It is not fully understood how antidepressants cause EPS, but a serotonergic input to dopaminergic pathways is a probable mechanism of action.Methods: Data from a multicenter drug-surveillance programme (AMSP, 'drug safety in psychiatry') which systemically documents severe drug reactions during psychiatric inpatient admissions, were reviewed to assess for EPS associated with antidepressant treatment. We identified 15 such cases, which were studied to detect similarities and to characterise risk factors.Results: We report on 15 patients with EPS following antidepressant-therapy between 1994 and 2016. EPS frequently occurred with selective serotonin reuptake inhibitor (SSRI) treatment alone (7/15 cases) or concomitant SSRI treatment (6/15 cases). EPS were most frequent with escitalopram-treatment (5 cases). The most common EPS was atypical dyskinesia (6/15 cases) followed by akathisia (4/15 cases). The mean age of onset for EPS was 54.93 years (SD 17.9). EPS occurred at any dosage and equally often in men and women.Conclusions: Our results highlight the possibility of EPS as an important, although uncommon, adverse effect of antidepressants. Clinicians should beware of this adverse effect and monitor early warning signs carefully.
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Affiliation(s)
- Sabrina Mörkl
- Department of Psychiatry and Psychotherapeutic Medicine, Medical University of Graz, Graz, Austria
| | - Daniel Seltenreich
- Department of Psychiatry and Psychotherapeutic Medicine, Medical University of Graz, Graz, Austria
| | - Martin Letmaier
- Department of Psychiatry and Psychotherapeutic Medicine, Medical University of Graz, Graz, Austria
| | - Susanne Bengesser
- Department of Psychiatry and Psychotherapeutic Medicine, Medical University of Graz, Graz, Austria
| | - Walter Wurm
- Department of Psychiatry and Psychotherapeutic Medicine, Medical University of Graz, Graz, Austria
| | - Renate Grohmann
- Department of Psychiatry and Psychotherapy, Ludwig-Maximilians-University, Munich, Germany
| | - Stefan Bleich
- Department of Psychiatry, Social Psychiatry and Psychotherapy, Hannover Medical School, Hannover, Germany
| | - Sermin Toto
- Department of Psychiatry, Social Psychiatry and Psychotherapy, Hannover Medical School, Hannover, Germany
| | - Susanne Stübner
- Department of Psychiatry and Psychotherapy, Ludwig-Maximilians-University, Munich, Germany
| | - Mary I Butler
- Department of Psychiatry and Neurobehavioral Science, University College Cork, Cork, Ireland
| | - Siegfried Kasper
- Department of Psychiatry and Psychotherapy, Medical University of Vienna, Vienna, Austria
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12
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Adaptive Resetting of Tuberoinfundibular Dopamine (TIDA) Network Activity during Lactation in Mice. J Neurosci 2020; 40:3203-3216. [PMID: 32209609 DOI: 10.1523/jneurosci.1553-18.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Revised: 02/26/2020] [Accepted: 02/27/2020] [Indexed: 01/22/2023] Open
Abstract
Giving birth triggers a wide repertoire of physiological and behavioral changes in the mother to enable her to feed and care for her offspring. These changes require coordination and are often orchestrated from the CNS, through as of yet poorly understood mechanisms. A neuronal population with a central role in puerperal changes is the tuberoinfundibular dopamine (TIDA) neurons that control release of the pituitary hormone, prolactin, which triggers key maternal adaptations, including lactation and maternal care. Here, we used Ca2+ imaging on mice from both sexes and whole-cell recordings on female mouse TIDA neurons in vitro to examine whether they adapt their cellular and network activity according to reproductive state. In the high-prolactin state of lactation, TIDA neurons shift to faster membrane potential oscillations, a reconfiguration that reverses upon weaning. During the estrous cycle, however, which includes a brief, but pronounced, prolactin peak, oscillation frequency remains stable. An increase in the hyperpolarization-activated mixed cation current, Ih, possibly through unmasking as dopamine release drops during nursing, may partially explain the reconfiguration of TIDA rhythms. These findings identify a reversible plasticity in hypothalamic network activity that can serve to adapt the dam for motherhood.SIGNIFICANCE STATEMENT Motherhood requires profound behavioral and physiological adaptations to enable caring for offspring, but the underlying CNS changes are poorly understood. Here, we show that, during lactation, neuroendocrine dopamine neurons, the "TIDA" cells that control prolactin secretion, reorganize their trademark oscillations to discharge in faster frequencies. Unlike previous studies, which typically have focused on structural and transcriptional changes during pregnancy and lactation, we demonstrate a functional switch in activity and one that, distinct from previously described puerperal modifications, reverses fully on weaning. We further provide evidence that a specific conductance (Ih) contributes to the altered network rhythm. These findings identify a new facet of maternal brain plasticity at the level of membrane properties and consequent ensemble activity.
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13
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Leem YH, Park JS, Chang H, Park J, Kim HS. Exercise Prevents Memory Consolidation Defects Via Enhancing Prolactin Responsiveness of CA1 Neurons in Mice Under Chronic Stress. Mol Neurobiol 2019; 56:6609-6625. [DOI: 10.1007/s12035-019-1560-z] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 03/13/2019] [Indexed: 12/21/2022]
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14
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Aquino NSS, Kokay IC, Perez CT, Ladyman SR, Henriques PC, Silva JF, Broberger C, Grattan DR, Szawka RE. Kisspeptin Stimulation of Prolactin Secretion Requires Kiss1 Receptor but Not in Tuberoinfundibular Dopaminergic Neurons. Endocrinology 2019; 160:522-533. [PMID: 30668693 DOI: 10.1210/en.2018-00932] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 01/14/2019] [Indexed: 02/07/2023]
Abstract
Kisspeptin has been shown to stimulate prolactin secretion. We investigated whether kisspeptin acts through the Kiss1 receptor (Kiss1r) to regulate dopamine and prolactin. Initially, we evaluated prolactin response in a Kiss1r-deficient mouse line, in which Kiss1r had been knocked into GnRH neurons (Kiss1r-/-R). Intracerebroventricular kisspeptin-10 (Kp-10) increased prolactin release in wild-type but not in Kiss1r-/-R female mice. In ovariectomized, estradiol-treated rats, the Kiss1r antagonist kisspeptin-234 abolished the Kp-10-induced increase in prolactin release but failed to prevent the concomitant reduction in the activity of tuberoinfundibular dopaminergic (TIDA) neurons, as determined by the 3,4-dihydroxyphenylacetic acid/dopamine ratio in the median eminence. Using whole-cell patch clamp recordings in juvenile male rats, we found no direct effect of Kp-10 on the electrical activity of TIDA neurons. In addition, dual-label in situ hybridization in the hypothalamus of female rats showed that Kiss1r is expressed in the periventricular nucleus of the hypothalamus (Pe) and arcuate nucleus of the hypothalamus (ARC) but not in tyrosine hydroxylase (Th)-expressing neurons. Kisspeptin also has affinity for the neuropeptide FF receptor 1 (Npffr1), which was expressed in the majority of Pe dopaminergic neurons but only in a low proportion of TIDA neurons in the ARC. Our findings demonstrate that Kiss1r is necessary to the effect of kisspeptin on prolactin secretion, although TIDA neurons lack Kiss1r and are electrically unresponsive to kisspeptin. Thus, kisspeptin is likely to stimulate prolactin secretion via Kiss1r in nondopaminergic neurons, whereas the colocalization of Npffr1 and Th suggests that Pe dopaminergic neurons may play a role in the kisspeptin-induced inhibition of dopamine release.
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Affiliation(s)
- Nayara S S Aquino
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Ilona C Kokay
- Centre for Neuroendocrinology and Department of Anatomy, University of Otago, Dunedin, New Zealand
| | | | - Sharon R Ladyman
- Centre for Neuroendocrinology and Department of Anatomy, University of Otago, Dunedin, New Zealand
| | - Patricia C Henriques
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
| | - Juneo F Silva
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
- Departamento de Ciências Biológicas, Universidade Estadual de Santa Cruz, Ilhéus, Brazil
| | | | - David R Grattan
- Centre for Neuroendocrinology and Department of Anatomy, University of Otago, Dunedin, New Zealand
| | - Raphael E Szawka
- Departamento de Fisiologia e Biofísica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil
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15
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Santana Y, Montejo AL, Martín J, LLorca G, Bueno G, Blázquez JL. Understanding the Mechanism of Antidepressant-Related Sexual Dysfunction: Inhibition of Tyrosine Hydroxylase in Dopaminergic Neurons after Treatment with Paroxetine but Not with Agomelatine in Male Rats. J Clin Med 2019; 8:jcm8020133. [PMID: 30678046 PMCID: PMC6406445 DOI: 10.3390/jcm8020133] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Revised: 01/13/2019] [Accepted: 01/21/2019] [Indexed: 01/23/2023] Open
Abstract
Antidepressant-related sexual dysfunction is a frequent adverse event caused by serotonergic activation that intensely affects quality of life and adherence in depressed patients. The dopamine system has multiple effects promoting sexual behavior, but no studies have been carried out to confirm dopaminergic changes involved in animal models after antidepressant use. Methods: The sexual behavior-related dopaminergic system in the rat was studied by comparing two different antidepressants and placebo for 28 days. The antidepressants used were paroxetine (a serotonergic antidepressant that causes highly frequent sexual dysfunction in humans) and agomelatine (a non-serotonergic antidepressant without associated sexual dysfunction). The tyrosine hydroxylase immunoreactivity (THI) in the substantia nigra pars compacta, the ventral tegmental area, the zona incerta, and the hypothalamic arcuate nucleus, as well as the dopaminergic projections to the striatum, hippocampus, cortex, and median eminence were analyzed. Results: The THI decreased significantly in the substantia nigra and ventral tegmental area after treatment with paroxetine, and the labeling was reduced drastically in the zona incerta and mediobasal hypothalamus. The immunoreactive axons in the target regions (striatum, cortex, hippocampus, and median eminence) almost disappeared only in the paroxetine-treated rats. Conversely, after treatment with agomelatine, a moderate reduction in immunoreactivity in the substantia nigra was found without appreciable modifications in the ventral tegmental area, zona incerta, and mediobasal hypothalamus. Nevertheless, no sexual or copulatory behavior was observed in any of the experimental or control groups. Conclusion: Paroxetine but not agomelatine was associated with important decreased activity in dopaminergic areas such as the substantia nigra and ventral tegmental areas that could be associated with sexual performance impairment in humans after antidepressant treatment.
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Affiliation(s)
- Yanira Santana
- Department of Psychiatry, Hospital Universitario de Salamanca, 37007 Salamanca, Spain.
| | - Angel L Montejo
- University of Salamanca, IBSAL, Nursing School E.U.E.F., 37007 Salamanca, Spain.
| | - Javier Martín
- Department of Statistics, School of Medicine, University of Salamanca, 37007 Salamanca, Spain.
| | - Ginés LLorca
- Department of Psychiatry, School of Medicine, University of Salamanca, 37007 Salamanca, Spain.
| | - Gloria Bueno
- Department of Psychiatry, School of Medicine, University of Salamanca, 37007 Salamanca, Spain.
| | - Juan Luis Blázquez
- Department of Human Anatomy and Histology, IBSAL NEUR-2, School of Medicine, University of Salamanca, 37007 Salamanca, Spain.
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16
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Giatti S, Diviccaro S, Panzica G, Melcangi RC. Post-finasteride syndrome and post-SSRI sexual dysfunction: two sides of the same coin? Endocrine 2018; 61:180-193. [PMID: 29675596 DOI: 10.1007/s12020-018-1593-5] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2018] [Accepted: 04/05/2018] [Indexed: 12/27/2022]
Abstract
Sexual dysfunction is a clinical condition due to different causes including the iatrogenic origin. For instance, it is well known that sexual dysfunction may occur in patients treated with antidepressants like selective serotonin reuptake inhibitors (SSRI). A similar side effect has been also reported during treatment with finasteride, an inhibitor of the enzyme 5alpha-reductase, for androgenetic alopecia. Interestingly, sexual dysfunction persists in both cases after drug discontinuation. These conditions have been named post-SSRI sexual dysfunction (PSSD) and post-finasteride syndrome (PFS). In particular, feeling of a lack of connection between the brain and penis, loss of libido and sex drive, difficulty in achieving an erection and genital paresthesia have been reported by patients of both conditions. It is interesting to note that the incidence of these diseases is probably so far underestimated and their etiopathogenesis is not sufficiently explored. To this aim, the present review will report the state of art of these two different pathologies and discuss, on the basis of the role exerted by three different neuromodulators such as dopamine, serotonin and neuroactive steroids, whether the persistent sexual dysfunction observed could be determined by common mechanisms.
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Affiliation(s)
- Silvia Giatti
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - Silvia Diviccaro
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy
| | - Giancarlo Panzica
- Dipartimento di Neuroscienze "Rita Levi Montalcini", Università degli studi di Torino, Neuroscience Institute Cavallieri Ottolenghi (NICO), Orbassano, Italy
| | - Roberto Cosimo Melcangi
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano, Milan, Italy.
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Multiple-scale neuroendocrine signals connect brain and pituitary hormone rhythms. Proc Natl Acad Sci U S A 2017; 114:2379-2382. [PMID: 28193889 DOI: 10.1073/pnas.1616864114] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Small assemblies of hypothalamic "parvocellular" neurons release their neuroendocrine signals at the median eminence (ME) to control long-lasting pituitary hormone rhythms essential for homeostasis. How such rapid hypothalamic neurotransmission leads to slowly evolving hormonal signals remains unknown. Here, we show that the temporal organization of dopamine (DA) release events in freely behaving animals relies on a set of characteristic features that are adapted to the dynamic dopaminergic control of pituitary prolactin secretion, a key reproductive hormone. First, locally generated DA release signals are organized over more than four orders of magnitude (0.001 Hz-10 Hz). Second, these DA events are finely tuned within and between frequency domains as building blocks that recur over days to weeks. Third, an integration time window is detected across the ME and consists of high-frequency DA discharges that are coordinated within the minutes range. Thus, a hierarchical combination of time-scaled neuroendocrine signals displays local-global integration to connect brain-pituitary rhythms and pace hormone secretion.
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18
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Hypocretin/Orexin Peptides Excite Rat Neuroendocrine Dopamine Neurons through Orexin 2 Receptor-Mediated Activation of a Mixed Cation Current. Sci Rep 2017; 7:41535. [PMID: 28145492 PMCID: PMC5286397 DOI: 10.1038/srep41535] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 12/19/2016] [Indexed: 11/11/2022] Open
Abstract
Hypocretin/Orexin (H/O) neurons of the lateral hypothalamus are compelling modulator candidates for the chronobiology of neuroendocrine output and, as a consequence, hormone release from the anterior pituitary. Here we investigate the effects of H/O peptides upon tuberoinfundibular dopamine (TIDA) neurons – cells which control, via inhibition, the pituitary secretion of prolactin. In whole cell recordings performed in male rat hypothalamic slices, application of H/O-A, as well as H/O-B, excited oscillating TIDA neurons, inducing a reversible depolarising switch from phasic to tonic discharge. The H/O-induced inward current underpinning this effect was post-synaptic (as it endured in the presence of tetrodotoxin), appeared to be carried by a Na+-dependent transient receptor potential-like channel (as it was blocked by 2-APB and was diminished by removal of extracellular Na+), and was a consequence of OX2R receptor activation (as it was blocked by the OX2R receptor antagonist TCS OX2 29, but not the OX1R receptor antagonist SB 334867). Application of the hormone, melatonin, failed to alter TIDA membrane potential or oscillatory activity. This first description of the electrophysiological effects of H/Os upon the TIDA network identifies cellular mechanisms that may contribute to the circadian rhythmicity of prolactin secretion.
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