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Bialy M, Bogacki-Rychlik W, Przybylski J, Zera T. The Sexual Motivation of Male Rats as a Tool in Animal Models of Human Health Disorders. Front Behav Neurosci 2019; 13:257. [PMID: 31956302 PMCID: PMC6947634 DOI: 10.3389/fnbeh.2019.00257] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2019] [Accepted: 10/30/2019] [Indexed: 12/27/2022] Open
Abstract
Normal or dysfunctional sexual behavior seems to be an important indicator of health or disease. Many health disorders in male patients affect sexual activity by directly causing erectile dysfunction, affecting sexual motivation, or both. Clinical evidence indicates that many diseases strongly disrupt sexual motivation and sexual performance in patients with depression, addiction, diabetes mellitus and other metabolic disturbances with obesity and diet-related factors, kidney and liver failure, circadian rhythm disorders, sleep disturbances including obstructive sleep apnea syndrome, developmental and hormonal disorders, brain damages, cardiovascular diseases, and peripheral neuropathies. Preclinical studies of these conditions often require appropriate experimental paradigms, including animal models. Male sexual behavior and motivation have been intensively investigated over the last 80 years in animal rat model. Sexual motivation can be examined using such parameters as: anticipatory behavior and 50-kHz ultrasonic vocalizations reflecting the emotional state of rats, initiation of copulation, efficiency of copulation, or techniques of classical (pavlovian) and instrumental conditioning. In this review article, we analyze the behavioral parameters that describe the sexual motivation and sexual performance of male rats in the context of animal experimental models of human health disorders. Based on analysis of the parameters describing the heterogeneous and complex structure of sexual behavior in laboratory rodents, we propose an approach that is useful for delineating distinct mechanisms affecting sexual motivation and sexual performance in selected disease states and the efficacy of therapy in preclinical investigations.
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Affiliation(s)
- Michal Bialy
- Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw, Warsaw, Poland
| | - Wiktor Bogacki-Rychlik
- Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw, Warsaw, Poland
| | - Jacek Przybylski
- Department of Biophysics and Human Physiology, Medical University of Warsaw, Warsaw, Poland
| | - Tymoteusz Zera
- Department of Experimental and Clinical Physiology, Laboratory of Centre for Preclinical Research, Medical University of Warsaw, Warsaw, Poland
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Xia JD, Chen J, Yang BB, Sun HJ, Zhu GQ, Dai YT, Yang J, Wang ZJ. Differences in sympathetic nervous system activity and NMDA receptor levels within the hypothalamic paraventricular nucleus in rats with differential ejaculatory behavior. Asian J Androl 2019. [PMID: 29516873 PMCID: PMC6038171 DOI: 10.4103/aja.aja_4_18] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Differences in intravaginal ejaculation latency reflect normal biological variation, but the causes are poorly understood. Here, we investigated whether variation in ejaculation latency in an experimental rat model is related to altered sympathetic nervous system (SNS) activity and expression of N-methyl-D-aspartic acid (NMDA) receptors in the paraventricular nucleus of the hypothalamus (PVN). Male rats were classified as “sluggish,” “normal,” and “rapid” ejaculators on the basis of ejaculation frequency during copulatory behavioral testing. The lumbar splanchnic nerve activity baselines in these groups were not significantly different at 1460 ± 480 mV, 1660 ± 600 mV, and 1680 ± 490 mV, respectively (P = 0.71). However, SNS sensitivity was remarkably different between the groups (P < 0.01), being 28.9% ± 8.1% in “sluggish,” 48.4% ± 7.5% in “normal,” and 88.7% ± 7.4% in “rapid” groups. Compared with “normal” ejaculators, the percentage of neurons expressing NMDA receptors in the PVN of “rapid” ejaculators was significantly higher, whereas it was significantly lower in “sluggish” ejaculators (P = 0.01). In addition, there was a positive correlation between the expression of NMDA receptors in the PVN and SNS sensitivity (r = 0.876, P = 0.02). This study shows that intravaginal ejaculatory latency is associated with SNS activity and is mediated by NMDA receptors in the PVN.
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Affiliation(s)
- Jia-Dong Xia
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210000, China
| | - Jie Chen
- Department of Obstetrics and Gynecology, Nanjing Drum Tower Hospital, Nanjing Medical University, Nanjing 210000, China
| | - Bai-Bing Yang
- Department of Andrology, Nanjing Drum Tower Hospital, Nanjing Medical University, Nanjing 210000, China
| | - Hai-Jian Sun
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing 210000, China
| | - Guo-Qing Zhu
- Key Laboratory of Cardiovascular Disease and Molecular Intervention, Department of Physiology, Nanjing Medical University, Nanjing 210000, China
| | - Yu-Tian Dai
- Department of Andrology, Nanjing Drum Tower Hospital, Nanjing Medical University, Nanjing 210000, China
| | - Jie Yang
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210000, China
| | - Zeng-Jun Wang
- Department of Urology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210000, China
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de Medeiros Silva A, de Santana MAD, de Góis Morais PLA, de Sousa TB, Januário Engelberth RCG, de Souza Lucena EE, Campêlo CLDC, Sousa Cavalcante J, Cavalcante JC, de Oliveira Costa MSM, Nascimento ESD. Serotonergic fibers distribution in the midline and intralaminar thalamic nuclei in the rock cavy (Kerodon rupestris). Brain Res 2014; 1586:99-108. [DOI: 10.1016/j.brainres.2014.08.047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2014] [Revised: 08/14/2014] [Accepted: 08/16/2014] [Indexed: 12/19/2022]
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Lau BWM, Yau SY, Lee TMC, Ching YP, Tang SW, So KF. Effect of corticosterone and paroxetine on masculine mating behavior: possible involvement of neurogenesis. J Sex Med 2010; 8:1390-403. [PMID: 20955318 DOI: 10.1111/j.1743-6109.2010.02081.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
INTRODUCTION Corticosterone inhibits male rodent sexual behavior while the mechanism remains obscured. Recent studies have disclosed that neurogenesis in the subventricular zone (SVZ) can be increased by pheromone exposure from the opposite sex, and neurogenesis is essential for normal mating behavior of female mice. Together with the neurogenesis-inhibiting effect of corticosterone, we hypothesize that cell proliferation in the olfactory system is essential for male rodent sexual functioning. AIM The current study explored the relationship between cell proliferation in the olfactory system and male sexual behavior. MAIN OUTCOME MEASURES Sexual behavior performance, proliferative cell counts, and c-fos-expressing cell counts. METHODS Adult male rats were treated with corticosterone and/or paroxetine, an antidepressant, for 2 weeks. These two drugs were shown to suppress and enhance hippocampus and SVZ cell proliferation, respectively. Mating behavior was assessed after the treatment, and proliferation of new cells and c-fos-expressing cells, activated neurons in the mating-related regions in the brain, were analyzed. To further confirm the necessity of cell proliferation in mating, inhibition of cell proliferation was performed by intracerebroventricular infusion of cytostatic cytosine arabinose (Ara-c). RESULTS Corticosterone treatment, which inhibited cell proliferation in both the SVZ and olfactory epithelium, led to inhibited male sexual performance. In contrast, paroxetine increased cell proliferation and improved the performance in corticosterone-treated animals. When cell proliferation in the brain was inhibited by Ara-c, a suppressed sexual performance was found. However, cell proliferation in olfactory epithelium was not inhibited by Ara-c and thus the sexual inhibition is unlikely to be linked to this region. Furthermore, a decrease in c-fos expression in the mating-related regions upon female pheromone stimulation was found. CONCLUSIONS These results suggest that cell proliferation in the SVZ and hippocampus may be involved in the reproduction of the male rodents, and pharmacological treatments may affect sexual functioning through alteration of neurogenesis.
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Affiliation(s)
- Benson Wui-Man Lau
- Department of Anatomy, The University of Hong Kong, Pokfulam, Hong Kong SAR, China
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Lau BWM, Yau SY, So KF. Reproduction: a new venue for studying function of adult neurogenesis? Cell Transplant 2010; 20:21-35. [PMID: 20887675 DOI: 10.3727/096368910x532765] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Adult neurogenesis has been a focus within the past few years because it is a newly recognized form of neuroplasticity that may play significant roles in behaviors and recovery process after disease. Mammalian adult neurogenesis could be found in two brain regions: hippocampus and subventricular zone (SVZ). While it is well established that hippocampal neurogenesis participates in memory formation and anxiety, the physiological function of SVZ neurogenesis is still under intense investigation. Recent studies disclose that SVZ neurogenesis is under regulation of reproductive cues like pheromones. Reciprocally, the newborn neurons may exert their effect on reproductive and maternal behaviors. This review discusses recent understanding of the interrelationship between neurogenesis and reproduction. The studies highlighted in this review illustrate the potential importance of neurogenesis in reproductive function and will provide new insights for the significance of adult neurogenesis.
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Affiliation(s)
- Benson Wui-Man Lau
- Department of Anatomy, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong SAR, PR China
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Serotonin and Sexual Behavior. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/s1569-7339(10)70089-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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Social instigation and aggressive behavior in mice: role of 5-HT1A and 5-HT1B receptors in the prefrontal cortex. Psychopharmacology (Berl) 2008; 201:237-48. [PMID: 18688602 PMCID: PMC4371733 DOI: 10.1007/s00213-008-1269-6] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/02/2008] [Accepted: 07/18/2008] [Indexed: 12/23/2022]
Abstract
RATIONALE Social instigation is used in rodents to induce high levels of aggression, a pattern of behavior with certain parallels to that of violent individuals. This procedure consists of a brief exposure to a provocative stimulus male, before direct confrontation with an intruder. Studies using 5-HT1A and 5-HT1B receptor agonists show an effective reduction in aggressive behavior. An important site of action for these drugs is the ventral orbitofrontal cortex (VO PFC), an area of the brain which is particularly relevant in the inhibitory control of aggressive and impulsive behavior. OBJECTIVES The objectives of the study are to assess the anti-aggressive effects of 5-HT1A and 5-HT1B agonist receptors [8-hydroxy-2-(di-n-propylamino) tetralin hydrobromide (8-OH-DPAT) and CP-93,129] in the VO PFC of socially provoked male mice. To confirm the specificity of the receptor, 5-HT1A and 5-HT1B antagonist receptors (WAY-100,635 and SB-224,289) were microinjected into the same area, in order to reverse the agonist effects. RESULTS 8-OH-DPAT (0.56 and 1.0 microg) reduced the frequency of attack bites. The lowest dose of CP-93,129 (0.1 microg) also decreased the number of attack bites and lateral threats. 5-HT1A and 5-HT1B receptor agonists differed in their effects on non-aggressive activities, the former decreasing rearing and grooming, and the latter, increasing these acts. Specific participation of the 1A and 1B receptors was verified by reversal of anti-aggressive effects using selective antagonists WAY-100,635 (10.0 microg) and SB-224,289 (1.0 microg). CONCLUSIONS The decrease in aggressiveness observed with microinjections of 5-HT1A and 5-HT1B receptor agonists into the VO PFC of socially provoked mice, supports the hypothesis that activation of these receptors modulates high levels of aggression in a behaviorally specific manner.
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Smith GT, Combs N. Serotonergic activation of 5HT1A and 5HT2 receptors modulates sexually dimorphic communication signals in the weakly electric fish Apteronotus leptorhynchus. Horm Behav 2008; 54:69-82. [PMID: 18336816 DOI: 10.1016/j.yhbeh.2008.01.009] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2007] [Revised: 01/20/2008] [Accepted: 01/24/2008] [Indexed: 11/17/2022]
Abstract
Serotonin modulates agonistic and reproductive behavior across vertebrate species. 5HT(1A) and 5HT(1B) receptors mediate many serotonergic effects on social behavior, but other receptors, including 5HT(2) receptors, may also contribute. We investigated serotonergic regulation of electrocommunication signals in the weakly electric fish Apteronotus leptorhynchus. During social interactions, these fish modulate their electric organ discharges (EODs) to produce signals known as chirps. Males chirp more than females and produce two chirp types. Males produce high-frequency chirps as courtship signals; whereas both sexes produce low-frequency chirps during same-sex interactions. Serotonergic innervation of the prepacemaker nucleus, which controls chirping, is more robust in females than males. Serotonin inhibits chirping and may contribute to sexual dimorphism and individual variation in chirping. We elicited chirps with EOD playbacks and pharmacologically manipulated serotonin receptors to determine which receptors regulated chirping. We also asked whether serotonin receptor activation generally modulated chirping or more specifically targeted particular chirp types. Agonists and antagonists of 5HT(1B/1D) receptors (CP-94253 and GR-125743) did not affect chirping. The 5HT(1A) receptor agonist 8OH-DPAT specifically increased production of high-frequency chirps. The 5HT(2) receptor agonist DOI decreased chirping. Receptor antagonists (WAY-100635 and MDL-11939) opposed the effects of their corresponding agonists. These results suggest that serotonergic inhibition of chirping may be mediated by 5HT(2) receptors, but that serotonergic activation of 5HT(1A) receptors specifically increases the production of high-frequency chirps. The enhancement of chirping by 5HT(1A) receptors may result from interactions with cortisol and/or arginine vasotocin, which similarly enhance chirping and are influenced by 5HT(1A) activity in other systems.
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Affiliation(s)
- G Troy Smith
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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Translational research into sexual disorders: Pharmacology and genomics. Eur J Pharmacol 2008; 585:426-35. [DOI: 10.1016/j.ejphar.2008.02.098] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2008] [Revised: 01/21/2008] [Accepted: 02/07/2008] [Indexed: 11/23/2022]
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Maciag D, Coppinger D, Paul IA. Evidence that the deficit in sexual behavior in adult rats neonatally exposed to citalopram is a consequence of 5-HT1 receptor stimulation during development. Brain Res 2006; 1125:171-5. [PMID: 17101120 PMCID: PMC1762094 DOI: 10.1016/j.brainres.2006.10.009] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Revised: 10/03/2006] [Accepted: 10/03/2006] [Indexed: 10/23/2022]
Abstract
Neonatal (postnatal days 8-21) exposure of rats to the selective serotonin reuptake inhibitor (SSRI), citalopram, results in persistent changes in behavior including decreased sexual activity in adult animals. We hypothesized that this effect was a consequence of abnormal stimulation of 5-HT(1A) and/or 5-HT(1B) receptors as a result of increased synaptic availability of serotonin during a critical period of development. We examined whether neonatal exposure to a 5-HT(1A) (8OH-DPAT) or a 5-HT(1B) (CGS 12066B) receptor agonist can mimic the effect of neonatal exposure to citalopram on adult sexual behavior. Results showed that neonatal treatment with 5-HT(1B) receptor agonist robustly impaired sexual behavior similar to the effect of citalopram, whereas exposure to 5-HT(1A) receptor agonist only moderately influenced male sexual activity in adult animals. These data support the hypothesis that stimulation of serotonin autoreceptors during development contributes to the adult sexual deficit in rats neonatally exposed to citalopram.
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Affiliation(s)
- Dorota Maciag
- Departments of Psychiatry & Human Behavior, University of Mississippi Medical Center, 2500 North State ST., Jackson, MS 39216-4505, USA
| | - David Coppinger
- Departments of Psychiatry & Human Behavior, University of Mississippi Medical Center, 2500 North State ST., Jackson, MS 39216-4505, USA
| | - Ian A. Paul
- Departments of Psychiatry & Human Behavior, University of Mississippi Medical Center, 2500 North State ST., Jackson, MS 39216-4505, USA
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Abstract
Premature ejaculation (PE) is a common male sexual disorder. Recent normative data suggest that men with an intravaginal ejaculatory latency time (IELT) of less than 1 minute have "definite" PE, while men with IELTs between 1 and 1.5 minutes have "probable" PE. Although there is insufficient empirical evidence to identify the etiology of PE, there is limited correlational evidence to suggest that men with PE have high levels of sexual anxiety and inherited altered sensitivity of central 5-HT (serotonin) receptors. Pharmacological modulation of the ejaculatory threshold using off-label daily or on-demand selective serotonin re-uptake inhibitors (SSRIs) offers patients a high likelihood of achieving improved ejaculatory control within a few days of initiating treatment, consequential improvements in sexual desire and other sexual domains and is well tolerated. Investigational drugs such as the ejaculo-selective serotonin transport inhibitors (ESSTIs) such as dapoxetine and UK-390,957 represent a major development in sexual medicine. These drugs offer patients the convenience of on-demand dosing, significant improvements in IELT, ejaculatory control, and sexual satisfaction with minimal adverse effects.
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Olivier B, Chan JSW, Pattij T, de Jong TR, Oosting RS, Veening JG, Waldinger MD. Psychopharmacology of male rat sexual behavior: modeling human sexual dysfunctions? Int J Impot Res 2006; 18 Suppl 1:S14-23. [PMID: 15843803 DOI: 10.1038/sj.ijir.3901330] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Most of our current understanding of the neurobiology, neuroanatomy and psychopharmacology of sexual behavior and ejaculatory function has been derived from preclinical studies in the rat. When a large population of male rats is tested on sexual activity during a number of successive tests, over time individual rats display a very stable sexual behavior that is either slow, normal or fast as characterized by the number of ejaculations performed. These sexual endophenotypes are postulated as rat counterparts of premature (fast rats) or retarded ejaculation (slow rats). Psychopharmacology in these endophenotypes helps to delineate the underlying mechanisms and pathology. This is illustrated by the effects of serotonergic antidepressants and serotonergic compounds on sexual and ejaculatory behavior of rats. These preclinical studies and models contribute to a better understanding of the neurobiology of ejaculation and boost the development of novel drug targets to treat ejaculatory disorders such as premature and retarded ejaculation.
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Affiliation(s)
- B Olivier
- Department of Psychopharmacology, Utrecht Institute for Pharmaceutical Sciences and Rudolf Magnus Institute of Neuroscience, Utrecht University, Utrecht, The Netherlands.
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McMahon CG, McMahon CN, Leow LJ, Winestock CG. Efficacy of type-5 phosphodiesterase inhibitors in the drug treatment of premature ejaculation: a systematic review. BJU Int 2006; 98:259-72. [PMID: 16879663 DOI: 10.1111/j.1464-410x.2006.06290.x] [Citation(s) in RCA: 93] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
This review examines the role of nitric oxide (NO) as a neurotransmitter involved in the central and peripheral control of ejaculation, the methods of phosphodiesterase type 5 inhibitor (PDE5I) drug treatment studies for premature ejaculation (PE), the adherence of methods to the contemporary consensus of ideal PE drug trial design, the impact of methods on treatment outcomes and the role of PDE5Is in the treatment of PE. NO/cGMP transduction is involved in both the central and peripheral control of emission, but evidence for a direct central or peripheral effect of PDE5Is on ejaculation is speculative. Thirteen of the 14 studies reviewed failed to fulfil the evidence-based medicine criteria for ideal PE drug trial design. Limitations of the studies include inadequately defined study populations, the lack of a double-blind placebo-controlled study design, and the absence of consistent objective physiological measures or sensitive, validated outcome assessment instruments as study endpoints. The broad range of intravaginal ejaculatory latency time (IELT) fold-increases reported with PDE5Is, on-demand selective serotonin re-uptake inhibitor (SSRI) drugs, and combined PDE5I/on-demand SSRIs is testament to the unreliability of data and conclusions from methodologically flawed studies. The one study that fulfilled the evidence-based medicine criteria of an ideal clinical trial design reported that treatment with sildenafil failed to significantly increase baseline IELT, supporting our conclusion that there is no convincing evidence to support any role for PDE5Is in the treatment of men with lifelong PE and normal erectile function. However, there is limited evidence to support a potential role for PDE5Is alone or combined with daily or on-demand SSRIs in the treatment of acquired PE in men with comorbid erectile dysfunction. Further controlled studies adhering to the contemporary consensus of ideal clinical trial design are required to clarify the role of PDE5Is in this subgroup of men with acquired PE.
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Affiliation(s)
- Chris G McMahon
- Australian Centre for Sexual Health, Suite 2-4, Berry Road Medical Centre, 1a Berry Road, St. Leonards, NSW, Australia 2065.
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14
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Pattij T, de Jong TR, Uitterdijk A, Waldinger MD, Veening JG, Cools AR, van der Graaf PH, Olivier B. Individual differences in male rat ejaculatory behaviour: searching for models to study ejaculation disorders. Eur J Neurosci 2005; 22:724-34. [PMID: 16101754 DOI: 10.1111/j.1460-9568.2005.04252.x] [Citation(s) in RCA: 98] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
In addition to investigating sexual function in rats that display normal ejaculatory behaviour, studying rats that are either 'hyposexual' or 'hypersexual' may provide important insights into the aetiology of ejaculatory dysfunctions in men, such as premature and retarded ejaculation. To this end, rats were matched into groups of 'sluggish', 'normal' and 'rapid' ejaculators based on their ejaculation frequencies displayed in a series of weekly sexual behaviour tests. Selecting rats on this parameter revealed large and stable differences in other parameters of sexual behaviour as well, including ejaculation latency and mount frequency but not intromission frequency and mount latency, putative indices of sexual motivation. Neuroanatomically, Fos immunoreactivity as a measure of neuronal activation was increased in rapid ejaculators compared with sluggish ejaculators in ejaculation-related brain areas, presumably associated with the differences in ejaculatory behaviour. Although the total number of oxytocin neurones within subregions of the hypothalamus did not differ between groups, in the supraoptic nucleus of the hypothalamus more oxytocin neurones were activated in rapid ejaculators compared with the other groups. Apart from the differences observed in ejaculatory behaviour, groups did not differ with respect to their locomotor activity and approach-avoidance behaviour as measured in the elevated plus-maze. Finally, apomorphine-induced stereotypy was similar in sluggish and rapid ejaculators, suggesting no large differences in dopamine susceptibility. Altogether, the present results suggest stable differences in male rat ejaculatory behaviour. Further exploring the neurobiological mechanisms underlying these differences may be a promising approach to gain insights into the aetiology of sexual dysfunctions such as premature, retarded or an-ejaculation.
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Affiliation(s)
- Tommy Pattij
- Department of Anatomy, University Medical Center St Radboud, Nijmegen, The Netherlands.
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15
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Waldinger MD, Olivier B. Animal models of premature and retarded ejaculation. World J Urol 2005; 23:115-8. [PMID: 15940532 DOI: 10.1007/s00345-004-0493-x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2004] [Accepted: 12/08/2004] [Indexed: 10/25/2022] Open
Abstract
Most of our current understanding of the neurobiology of sexual behavior and ejaculatory function has been derived from animal studies using rats with normal sexual behaviour. However, none of these proposed models adequately represents human ejaculatory disorders. Based on the "ejaculation distribution theory", which postulates that the intravaginal ejaculation latency time in men is represented by a biological continuum, we have developed an animal model for the research of premature and delayed ejaculation. In this model, a large number of male Wistar rats are investigated during 4-6 weekly sexual behavioural tests. Based on the number of ejaculations during 30 min tests, rapid and sluggish ejaculating rats are distinguished, each representing approximately 10% at both ends of a Gaussian distribution. Together with other parameters, such as ejaculation latency time, these rats at either side of the spectrum resemble men with premature and delayed ejaculation, respectively. Comparable to the human situation, in a normal population of rats, endophenotypes exist with regard to basal sexual (ejaculatory) performance.
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Affiliation(s)
- Marcel D Waldinger
- Department of Psychiatry and Neurosexology, Leyenburg Haga Hospital, Leyweg 275, 2545 CH The Hague, The Netherlands.
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Chambliss HO, Van Hoomissen JD, Holmes PV, Bunnell BN, Dishman RK. Effects of chronic activity wheel running and imipramine on masculine copulatory behavior after olfactory bulbectomy. Physiol Behav 2004; 82:593-600. [PMID: 15327906 DOI: 10.1016/j.physbeh.2004.04.064] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2003] [Revised: 03/11/2004] [Accepted: 04/23/2004] [Indexed: 10/26/2022]
Abstract
We examined the effects of chronic activity wheel running and imipramine administration on appetitive behavior after olfactory bulbectomy (OBX). Male Long-Evans rats were randomly assigned to the following conditions using a 2 x 2 x 2 design: (1) bilateral OBX or sham surgery, (2) voluntary activity wheel running or sedentary home cage, and (3) daily imipramine or saline injections. After 21 days of treatment, animals underwent behavioral testing for copulatory activity and sucrose preference. Bulbectomized animals exhibited decrements in copulatory performance and reductions in sucrose intake compared to sham animals. Within the bulbectomized groups, imipramine-treated rats either did not copulate or had reduced ejaculation frequencies. However, activity wheel running attenuated the copulatory deficits induced by OBX. The findings encourage studies of physical activity and male sexual dysfunction among depressed men being treated by pharmacotherapy.
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Affiliation(s)
- Heather O Chambliss
- Centers for Integrated Health Research, The Cooper Institute, Dallas, TX, USA
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Heimer L. The legacy of the silver methods and the new anatomy of the basal forebrain: implications for neuropsychiatry and drug abuse. Scand J Psychol 2003; 44:189-201. [PMID: 12914582 DOI: 10.1111/1467-9450.00336] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The first part of the paper highlights the remarkable legacy of the silver methods, with special emphasis on the travails and opportunities offered by the various Nauta methods and their modifications. When the tracer methods based on axoplasmic flow were introduced in the early 1970s, they were exploited on a backdrop of a basic anatomical framework, which had already been established through the tracing of the major CNS pathways by the aid of the silver methods, especially the widely used Nauta-Gygax methods and their modifications. Some of the silver methods that were developed in the late 1960s for the staining of degenerating boutons (e.g. the Fink-Heimer method and de Olmos cupric silver method) provided the necessary technical improvements that eventually led to a new and more productive way to look at the basal forebrain functional/anatomical organization; if it was not for the silver methods, we would in all likelihood still be promoting the nebulous notion of the substantia innominata rather than the concepts of the ventral striatopallidal system and the extended amygdala. The discovery and elaboration of these two macroanatomical systems symbolize what might deservedly be called the "new anatomy" of the basal forebrain. Following a review of the critical experiments which led to the development of the new anatomy of the basal forebrain, its topography in the human is reviewed in drawings of an abbreviated series of coronal sections. The discovery of the ventral striatopallidal system and its thalamic projection to the mediodorsal thalamus rather than to the ventral anterior-ventral lateral thalamic complex ushered in the idea of parallel cortico-subcortical reentrant circuits, which to a large extent has replaced the limbic system as a theoretical framework for neuropsychiatric disorders. The extended amygdala, which appears as a large ring formation around the internal capsule, is still controversial in some quarters, although it is slowly but surely making its way into the general neuroscience literature, especially in the field of addictive disorders. The ventral striatopallidal system and the extended amygdala are interwoven in a complex fashion with the basal nucleus of Meynert within the basal forebrain. Together, these three systems represent important output channels for so-called "limbic" forebrain regions, especially orbitomedial prefrontal cortex and medial temporal lobe structures, which are increasingly implicated in major neuropsychiatric disorders.
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Affiliation(s)
- Lennart Heimer
- Departments of Neurosurgery and Neuroscience, University of Virginia, Charlottesville, Virginia 22908, USA.
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Aznar S, Qian Z, Shah R, Rahbek B, Knudsen GM. The 5-HT1A serotonin receptor is located on calbindin- and parvalbumin-containing neurons in the rat brain. Brain Res 2003; 959:58-67. [PMID: 12480158 DOI: 10.1016/s0006-8993(02)03727-7] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The 5-HT(1A) receptor is a well-characterized serotonin receptor playing a role in many central nervous functions and known to be involved in depression and other mental disorders. In situ hybridization, immunocytochemical, and binding studies have shown that the 5-HT(1A) receptor is widely distributed in the rat brain, with a particularly high density in the limbic system. The receptor's localization in the different neuronal subtypes, which may be of importance for understanding its role in neuronal circuitries, is, however, unknown. In this study we show by immunocytochemical double-labeling techniques, that the 5-HT(1A) receptor is present on both pyramidal and principal cells, and calbindin- and parvalbumin-containing neurons, which generally define two different subtypes of interneurons. Moreover, semiquantitative analysis showed that the receptor's distribution in the different neuronal types varies between brain areas. In cortex, hippocampus, hypothalamus, and amygdala the receptor was located on both principal cells and calbindin- and parvalbumin-containing neurons. In septum and thalamus, the receptor was mostly present on calbindin- and parvalbumin-containing cells. Especially in the medial septum and thalamic reticular nucleus, the receptor highly colocalized with parvalbumin-positive neurons. These results suggest a diverse function of the 5-HT(1A) receptor in modulating neuronal circuitry in different brain areas, that may depend on the type of neuron the receptor is predominantly located on.
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Affiliation(s)
- Susana Aznar
- Neurobiology Research Unit, Unit 9201, Copenhagen University Hospital, Blegdamsvej 9, 2100 Copenhagen, Denmark.
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Hayes ES, Adaikan PG. Metachlorophenylpiperazine (m-CPP) induced intracavernous pressure responses in anaesthetized rats. Int J Impot Res 2002; 14:287-94. [PMID: 12152119 DOI: 10.1038/sj.ijir.3900888] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2001] [Accepted: 04/25/2002] [Indexed: 11/09/2022]
Abstract
Here we have recorded the effects of metachlorophenylpiperazine (m-CPP) on intracavernous pressure (ICP) in anesthetized rats pretreated with various pharmacological agents in an attempt to determine the mechanism and relevance of the m-CPP induced ICP response to other models of erection. m-CPP elicited consistent and significantly greater increases in ICP (71.5+/-6.6 mmHg) compared with the mixed 5-HT(2a/2c) agonists trifluoromethylphenylpiperazine (3.4+/-1.3 mmHg) and quipazine (10.9+/-1.8 mmHg). Blockade of 5-HT(2a) receptors with ketanserin failed to unmask any stimulatory effect of quipazine (7.2+/-1.0 mmHg). m-CPP induced ICP responses (71+/-7.0 mmHg) were unaffected in the presence of mianserin (63+/-5 mmHg) and ketanserin (51+/-12 mmHg). Spiperone significantly reduced the m-CPP induced increase in ICP (8.0+/-1.0 mmHg). Naloxone, yohimbine and 8-hydroxy-2-(di-n-propylamino)tetralin (8-OHDPAT) failed to elicit increases in ICP on their own. All three drugs significantly reduced the latency to the first m-CPP induced ICP response compared to saline. Yohimbine increased the duration of m-CPP induced ICP responses whereas 8-OHDPAT increased the mean number of m-CPP induced ICP responses compared to saline. The effects of m-CPP on ICP in anesthetized rats may not be mediated by 5-HT(2c) receptors and appears to be similar to erection in copula, but not erection elicited by other drugs or penile sheath retraction.
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Affiliation(s)
- E S Hayes
- Department of Obstetrics and Gynaecology, the National University of Singapore, Singapore.
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Arteaga M, Motte-Lara J, Velázquez-Moctezuma J. Effects of yohimbine and apomorphine on the male sexual behaviour pattern of the golden hamster (Mesocricetus auratus). Eur Neuropsychopharmacol 2002; 12:39-45. [PMID: 11788239 DOI: 10.1016/s0924-977x(01)00134-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
It has been reported that the copulatory pattern of male hamsters differs from that displayed by most rodents. Besides mount, intromission and ejaculatory patterns, male hamsters display a peculiar copulatory pattern known as long intromission (LI). This peculiar behavioural pattern emerges after the male has been allowed to ejaculate repeatedly. Although LIs have been linked to sexual exhaustion, their functional meaning and their pharmacological regulation have not yet been elucidated. In this study, the sexual behaviour pattern of male golden hamsters was analysed after the administration of yohimbine and apomorphine, drugs that selectively acts on the noradrenergic and dopaminergic system, respectively. Both drugs have proved effective in inducing facilitation of masculine sexual behaviour in several species, including rodents. Results showed that, as in rats, the administration of yohimbine and apomorphine in male hamsters seems to have a stimulatory effect on masculine sexual behaviour, although their effects differ in characteristics and in intensity. In particular, after yohimbine administration, the onset of LIs appears sooner than in control subjects and it seems that they are linked to the number of ejaculations. In addition, sexual activity seems increased after the onset of LIs, including an increase in ejaculations and in the number of LIs. On the other hand, apomorphine administration induced just a slight stimulatory effect limited to ejaculatory latency and postejaculatory interval. Concerning LIs, apomorphine induced a complete disappearance of LIs in 60% of the subjects. The full significance of these findings remains to be elucidated.
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Affiliation(s)
- M Arteaga
- Departamento de Biología de la Reproducción, Universidad Autónoma Metropolitana, Iztapalapa, Apartado Postal 55 535, 09340, Mexico City C.P., Mexico
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