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Bogacki-Rychlik W, Gawęda K, Bialy M. Neurophysiology of male sexual arousal-Behavioral perspective. Front Behav Neurosci 2024; 17:1330460. [PMID: 38333545 PMCID: PMC10851294 DOI: 10.3389/fnbeh.2023.1330460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2023] [Accepted: 12/15/2023] [Indexed: 02/10/2024] Open
Abstract
In the presented review, we analyzed the physiology of male sexual arousal and its relation to the motivational aspects of this behavior. We highlighted the distinction between these processes based on observable physiological and behavioral parameters. Thus, we proposed the experimentally applicable differentiation between sexual arousal (SA) and sexual motivation (SM). We propose to define sexual arousal as an overall autonomic nervous system response leading to penile erection, triggered selectively by specific sexual cues. These autonomic processes include both spinal and supraspinal neuronal networks, activated by sensory pathways including information from sexual partner and sexual context, as well as external and internal genital organs. To avoid misinterpretation of experimental data, we also propose to precise the term "sexual motivation" as all actions performed by the individual that increase the probability of sexual interactions or increase the probability of exposition to sexual context cues. Neuronal structures such as the amygdala, bed nucleus of stria terminalis, hypothalamus, nucleus raphe, periaqueductal gray, and nucleus paragigantocellularis play crucial roles in controlling the level of arousal and regulating peripheral responses via specific autonomic effectors. On the highest level of CNS, the activity of cortical structures involved in the regulation of the autonomic nervous system, such as the insula and anterior cingulate cortex, can visualize an elevated level of SA in both animal and human brains. From a preclinical perspective, we underlie the usefulness of the non-contact erection test (NCE) procedure in understanding factors influencing sexual arousal, including studies of sexual preference in animal models. Taken together results obtained by different methods, we wanted to focus attention on neurophysiological aspects that are distinctly related to sexual arousal and can be used as an objective parameter, leading to higher translational transparency between basic, preclinical, and clinical studies.
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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
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Kondo Y, Hayashi H. Neural and Hormonal Basis of Opposite-Sex Preference by Chemosensory Signals. Int J Mol Sci 2021; 22:8311. [PMID: 34361077 DOI: 10.3390/ijms22158311] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Revised: 07/28/2021] [Accepted: 07/29/2021] [Indexed: 12/13/2022] Open
Abstract
In mammalian reproduction, sexually active males seek female conspecifics, while estrous females try to approach males. This sex-specific response tendency is called sexual preference. In small rodents, sexual preference cues are mainly chemosensory signals, including pheromones. In this article, we review the physiological mechanisms involved in sexual preference for opposite-sex chemosensory signals in well-studied laboratory rodents, mice, rats, and hamsters of both sexes, especially an overview of peripheral sensory receptors, and hormonal and central regulation. In the hormonal regulation section, we discuss potential rodent brain bisexuality, as it includes neural substrates controlling both masculine and feminine sexual preferences, i.e., masculine preference for female odors and the opposite. In the central regulation section, we show the substantial circuit regulating sexual preference and also the influence of sexual experience that innate attractants activate in the brain reward system to establish the learned attractant. Finally, we review the regulation of sexual preference by neuropeptides, oxytocin, vasopressin, and kisspeptin. Through this review, we clarified the contradictions and deficiencies in our current knowledge on the neuroendocrine regulation of sexual preference and sought to present problems requiring further study.
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Abstract
Among the intact male rats, a subpopulation has been found to show little or no sexual behavior, even after experiencing several mating sessions. This study investigated whether sexually sluggish (SS) males show behavioral differences from normal copulatory (NC) males, other than those concerning sexual behavior. The olfactory preference of males was measured through the time spent displaying nose-poking behavior directed at sexually active males and estrous females for odor exploration in a three-chamber apparatus. Both the NC and SS males showed a significant preference for the odor of estrous females compared with that of male odors. However, SS males spent significantly less time nose-poking estrous females than NC males. The food-finding test was performed after overnight fasting. Our findings showed that all the NC males found the buried pellet within 5 min, whereas over 60% of the SS males failed to find it. The males were also tested for their ability to find a buried bag containing soiled bedding from estrous female cages. The bag was found by 80% of NC males, but only by 20% of SS males. Our results suggest that SS and NC male rats differ not only in sexual behavior but also in other functions such as olfaction.
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Affiliation(s)
- Yui Shimomi
- Department of Animal Sciences, Faculty of Life and Environmental Sciences, Teikyo University of Science, 2525 Yatsusawa, Uenohara, Yamanashi 409-0193, Japan
| | - Yasuhiko Kondo
- Department of Animal Sciences, Faculty of Life and Environmental Sciences, Teikyo University of Science, 2525 Yatsusawa, Uenohara, Yamanashi 409-0193, Japan
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Gao T, Yin Z, Wang M, Fang Z, Zhong X, Li J, Hu Y, Wu D, Jiang K, Xu X. The effects of pubertal exposure to bisphenol-A on social behavior in male mice. Chemosphere 2020; 244:125494. [PMID: 31812767 DOI: 10.1016/j.chemosphere.2019.125494] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 11/19/2019] [Accepted: 11/26/2019] [Indexed: 05/20/2023]
Abstract
Puberty is a crucial developmental period for structural modifications of brain and activation of the neural circuits underlying sex differences in social behavior. It is possible that pubertal exposure to bisphenol-A (BPA), a common EED with a weak estrogenic activity, influences social behavior. After being exposed to BPA at 0.04, 0.4, 4 mg kg-1 for 18 days, the 7-week-old male mice were tested with social play and three-chamber. The results showed that pubertal BPA exposure decreased social play between adolescent males and sociability of adolescent males. Further, pubertal BPA exposure reduced sociability and inhibited social novel preferences of adult males. BPA inhibited social interactions with opposite sex but improved socio-sexual exploration and the low-intensity mating behavior (mounting) with same sex in adult males. In residential-intruder test, BPA-exposed adult males showed a decrease in aggressiveness and an enhancement in prosocial behavior with intruder. Western blot analysis showed that BPA (especially at 4 mg/kg/d) down-regulated the levels of AR in the amygdala and the striatum but up-regulated the levels of DR1 and DAT proteins in the striatum of adult males. BPA at 4 mg kg-1 decreased the levels of T in the serum and the brain. These results suggest that pubertal BPA exposure affects social play and sociability of adolescent males and even results in long-term effects on social behavior of adult males. BPA-induced down-regulations of the levels of AR in the amygdala and the striatum and up-regulation of the levels of DR1 and DAT in the striatum may be involved.
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Affiliation(s)
- Tongtong Gao
- Chemistry and Life Sciences College, Key Laboratory of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Provincial Key Laboratory of Ecology, Zhejiang Normal University, PR China
| | - Zhangxin Yin
- Chemistry and Life Sciences College, Key Laboratory of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Provincial Key Laboratory of Ecology, Zhejiang Normal University, PR China
| | - Muye Wang
- Chemistry and Life Sciences College, Key Laboratory of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Provincial Key Laboratory of Ecology, Zhejiang Normal University, PR China
| | - Zhaoqing Fang
- Chemistry and Life Sciences College, Key Laboratory of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Provincial Key Laboratory of Ecology, Zhejiang Normal University, PR China
| | - Xiaoyu Zhong
- Chemistry and Life Sciences College, Key Laboratory of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Provincial Key Laboratory of Ecology, Zhejiang Normal University, PR China
| | - Jishui Li
- Chemistry and Life Sciences College, Key Laboratory of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Provincial Key Laboratory of Ecology, Zhejiang Normal University, PR China
| | - Yizhong Hu
- Chemistry and Life Sciences College, Key Laboratory of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Provincial Key Laboratory of Ecology, Zhejiang Normal University, PR China
| | - Donghong Wu
- Chemistry and Life Sciences College, Key Laboratory of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Provincial Key Laboratory of Ecology, Zhejiang Normal University, PR China
| | - Kesheng Jiang
- Chemistry and Life Sciences College, Key Laboratory of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Provincial Key Laboratory of Ecology, Zhejiang Normal University, PR China
| | - Xiaohong Xu
- Chemistry and Life Sciences College, Key Laboratory of Wildlife Biotechnology and Conservation and Utilization of Zhejiang Province, Zhejiang Provincial Key Laboratory of Ecology, Zhejiang Normal University, PR China.
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Abstract
Sexual attraction has two components: Emission of sexually attractive stimuli and responsiveness to these stimuli. In rodents, olfactory stimuli are necessary but not sufficient for attraction. We argue that body odors are far superior to odors from excreta (urine, feces) as sexual attractants. Body odors are produced by sebaceous glands all over the body surface and in specialized glands. In primates, visual stimuli, for example the sexual skin, are more important than olfactory. The role of gonadal hormones for the production of and responsiveness to odorants is well established. Both the androgen and the estrogen receptor α are important in male as well as in female rodents. Also in primates, gonadal hormones are necessary for the responsiveness to sexual attractants. In males, the androgen receptor is sufficient for sustaining responsiveness. In female non-human primates, estrogens are needed, whereas androgens seem to contribute to responsiveness in women.
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Affiliation(s)
| | - Anders Ågmo
- Department of Psychology, University of Tromsø, Norway.
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Violante‐Soria V, Cruz SL, Rodríguez‐Manzo G. Sexual behaviour is impaired by the abused inhalant toluene in adolescent male rats. Eur J Neurosci 2018; 50:2113-2123. [DOI: 10.1111/ejn.13969] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Revised: 05/06/2018] [Accepted: 05/17/2018] [Indexed: 12/16/2022]
Affiliation(s)
| | - Silvia L. Cruz
- Departamento de Farmacobiología Cinvestav‐Sede Sur Mexico City Mexico
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Petrulis A. Chemosignals and hormones in the neural control of mammalian sexual behavior. Front Neuroendocrinol 2013; 34:255-67. [PMID: 23911848 DOI: 10.1016/j.yfrne.2013.07.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Revised: 07/19/2013] [Accepted: 07/22/2013] [Indexed: 01/05/2023]
Abstract
Males and females of most mammalian species depend on chemosignals to find, attract and evaluate mates and, in most cases, these appetitive sexual behaviors are strongly modulated by activational and organizational effects of sex steroids. The neural circuit underlying chemosensory-mediated pre- and peri-copulatory behavior involves the medial amygdala (MA), the bed nucleus of the stria terminalis (BNST), medial preoptic area (MPOA) and ventromedial hypothalamus (VMH), each area being subdivided into interconnected chemoreceptive and hormone-sensitive zones. For males, MA-BNST connections mediate chemoinvestigation whereas the MA-MPOA pathway regulates copulatory initiation. For females, MA-MPOA/BNST connections also control aspects of precopulatory behavior whereas MA-VMH projections control both precopulatory and copulatory behavior. Significant gaps in understanding remain, including the role of VMH in male behavior and MPOA in female appetitive behavior, the function of cortical amygdala, the underlying chemical architecture of this circuit and sex differences in hormonal and neurochemical regulation of precopulatory behavior.
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Affiliation(s)
- Aras Petrulis
- Georgia State University, Neuroscience Institute, 100 Piedmont Ave SE, Atlanta, GA 30303, USA.
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Nielsen BL, Jerôme N, Saint-Albin A, Rampin O, Maurin Y. Behavioural response of sexually naïve and experienced male rats to the smell of 6-methyl-5-hepten-2-one and female rat faeces. Physiol Behav 2013; 120:150-5. [PMID: 23911690 DOI: 10.1016/j.physbeh.2013.07.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2013] [Revised: 05/31/2013] [Accepted: 07/23/2013] [Indexed: 01/09/2023]
Abstract
Sexually experienced male rats display penile erections when exposed to faeces from mammalian females in oestrus (Rampin et al., Behav Brain Res, 172:169, 2006), suggesting that specific odours indicate female receptiveness across species. However, it is unknown to what extent the sexual response observed results from an odorous conditioning acquired during sexual experience. We tested the behavioural response of male Brown Norway rats both when sexually naïve and experienced to four odours, including oestrous rat faeces and 6-methyl-5-hepten-2-one (methylheptenone; a molecule found in higher concentrations during oestrus in female rats, foxes and horses). Odour had a significant effect on the sexual response of the naïve rats, with oestrus faeces provoking significantly more erections than herb odour, and with methylheptenone and di-oestrus faeces being intermediate. This indicates that sexually naïve male rats have an unconditioned ability to detect oestrous mediated via odour. After gaining sexual experience, the response to methylheptenone, di- and oestrus faeces was significantly higher than that observed with herb odour. These results strongly suggest that methylheptenone is part of the odorous bouquet of oestrus and contributes to the olfactory determination of female receptiveness.
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Abstract
Many mammalian species use chemosignals to coordinate reproduction by altering the physiology and behavior of both sexes. Chemosignals prime reproductive physiology so that individuals become sexually mature and active at times when mating is most probable and suppress it when it is not. Once in reproductive condition, odors produced and deposited by both males and females are used to find and select individuals for mating. The production, dissemination and appropriate responses to these cues are modulated heavily by organizational and activational effects of gonadal sex steroids and thereby intrinsically link chemical communication to the broader reproductive context. Many compounds have been identified as "pheromones" but very few have met the expectations of that term: a unitary, species-typical substance that is both necessary and sufficient for an experience-independent behavioral or physiological response. In contrast, most responses to chemosignals are dependent or heavily modulated by experience, either in adulthood or during development. Mechanistically, chemosignals are perceived by both main and accessory (vomeronasal) olfactory systems with the importance of each system tied strongly to the nature of the stimulus rather than to the response. In the central nervous system, the vast majority of responses to chemosignals are mediated by cortical and medial amygdala connections with hypothalamic and other forebrain structures. Despite the importance of chemosignals in mammals, many details of chemical communication differ even among closely related species and defy clear categorization. Although generating much research and public interest, strong evidence for the existence of a robust chemical communication among humans is lacking.
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Affiliation(s)
- Aras Petrulis
- Georgia State University, Neuroscience Institute, Atlanta, GA 30303, USA.
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Abstract
Intrauterine implantation of fertilized ova can be blocked by exposing recently inseminated females with an unfamiliar male. This selective pregnancy failure, designated as the Bruce effect (Bruce, Nature 1959; 184:105), is well studied in laboratory mice and has been confirmed in several other rodent species. However, no clear information exists concerning this phenomenon in the laboratory rat. The present study was conducted to investigate whether or not the Bruce effect exists in the rat. Females of two F1 hybrid strains (n(total) = 354) with different MHC genotypes (F344BNF1, RT1(lv1/n), and LEWPVGF1, RT1(l/c)) were mated with males of their own strain and subsequently exposed during the first 4 days postcoitus either to a male of the other hybrid strain or to an unfamiliar male of the same strain as the stud. The litter rate of each treatment group was determined. As a control, mated females of both strains were reexposed to the stud male to determine baseline litter rates. Female rats of both F1 hybrid strains showed a significantly lower litter rate when exposed to males of a different strain than their stud male, compared to the expected values of birth rates observed in control females (F344BNF1: P = 0.017; LEWPVGF1: P = 0.019). In contrast, there was no difference between expected and observed litter rates in females of both F1 hybrid strains after exposure to an unfamiliar male of the same strain as their stud. Our results demonstrate for the first time that the Bruce effect, well documented in mice, occurs in the Norway rat.
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Affiliation(s)
- Vera Marashi
- Institute of Laboratory Animal Science, University of Veterinary Medicine Vienna, Austria
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Dhungel S, Masaoka M, Rai D, Kondo Y, Sakuma Y. Both olfactory epithelial and vomeronasal inputs are essential for activation of the medial amygdala and preoptic neurons of male rats. Neuroscience 2011; 199:225-34. [PMID: 21983295 DOI: 10.1016/j.neuroscience.2011.09.051] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 09/26/2011] [Accepted: 09/26/2011] [Indexed: 11/30/2022]
Abstract
Chemosensory inputs signaling volatile and nonvolatile molecules play a pivotal role in sexual and social behavior in rodents. We have demonstrated that olfactory preference in male rats, that is, attraction to receptive female odors, is regulated by the medial amygdala (MeA), the cortical amygdala (CoA), and the preoptic area (POA). In this paper, we investigated the involvement of two chemosensory organs, the olfactory epithelium (OE) and the vomeronasal organ (VNO), in olfactory preference and copulatory behavior in male rats. We found that olfactory preferences were impaired by zinc sulfate lesion of the OE but not surgical removal of the VNO. Copulatory behaviors, especially intromission frequency and ejaculation, were also suppressed by zinc sulfate treatment. Neuronal activation in the accessory olfactory bulb (AOB), the MeA, the CoA, and the POA was analyzed after stimulation by airborne odors or soiled bedding of estrous females using cFos immunohistochemistry. Although the OE and VNO belong to different neural systems, the main and accessory olfactory systems, respectively, both OE lesion and VNO removal almost equally suppressed the number of cFos-immunoreactive cells in those areas that regulate olfactory preference. These results suggest that signals received by the OE and VNO interact and converge in the early stage of olfactory processing, in the AOB and its targets, although they have distinct roles in the regulation of social behaviors.
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Affiliation(s)
- S Dhungel
- Department of Physiology, Nippon Medical School, 1-1-5 Sendagi, Bunkyo, Tokyo 113-8602, Japan
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Bialy M, Nikolaev-Diak A, Kalata U, Nikolaev E. Blockade of androgen receptor in the medial amygdala inhibits noncontact erections in male rats. Physiol Behav 2011; 103:295-301. [PMID: 21315100 DOI: 10.1016/j.physbeh.2011.02.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2010] [Revised: 01/27/2011] [Accepted: 02/02/2011] [Indexed: 11/21/2022]
Abstract
Our previous work demonstrated that androgens in the medial amygdala (MeA) of castrated male rats maintained noncontact erections (NCEs), which occur during exposure to an inaccessible receptive female, for one week after implantation. The present experiments investigated the effects of implantation into the MeA of either flutamide (F), a blocker of androgen receptors, or of 1,4,6-androstatrien-3,17-dione (ATD), which blocks aromatization of testosterone. One day after implantation of F, fewer males displayed NCEs, and had longer latencies to the first NCE and fewer NCEs, and spent less total time in genital grooming, compared to the control group. ATD had only weak facilitative effects on some measures of NCEs. These results suggest that androgen receptors in the MeA play a major role in the regulation of NCEs and that the MeA is one of the neuronal structures that regulate male sexual arousal. Furthermore, it is sensitive to relatively fast changes in the level of androgen receptors stimulation.
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Yeh KY, Liu YZ, Tai MY, Tsai YF. Ginkgo biloba extract treatment increases noncontact erections and central dopamine levels in rats: role of the bed nucleus of the stria terminalis and the medial preoptic area. Psychopharmacology (Berl) 2010; 210:585-90. [PMID: 20411379 DOI: 10.1007/s00213-010-1861-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Accepted: 04/04/2010] [Indexed: 11/30/2022]
Abstract
RATIONALE Penile erection is necessary for successful copulation in males. The extract of Ginkgo biloba leaves (EGb 761) significantly facilitates copulation in male rats, but the effect of EGb 761 on noncontact erection (NCE) remains unknown. OBJECTIVE The present study was conducted to evaluate the influence of EGb 761 on NCE in male rats. MATERIALS AND METHODS Adult Long-Evans male rats were treated with 50 mg/kg of EGb 761 (experimental group) or distilled water (control group) by gavage for 14 days. The NCE test was carried out after 14 days of EGb 761 treatment, and the latency and the numbers of NCE were recorded. Approximately 14 h following the NCE behavioral tests, animals were sacrificed by means of decapitation, and levels of dopamine in the bed nucleus of the stria terminalis (BNST) and medial preoptic area (MPOA) were measured by means of high-pressure liquid chromatography with electrochemical detection. RESULTS Chronic treatment with EGb 761 significantly decreased the NCE latency, but increased the number of NCEs and the dopamine levels in the BNST and MPOA in rats compared to the controls. CONCLUSION Treatment with EGb 761 increased both NCEs and the dopamine contents in the BNST and the MPOA. These results suggest that enhanced NCEs in the rats administered with EGb 761 may be related to dopaminergic activity in the BNST and MPOA.
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Affiliation(s)
- Kuei-Ying Yeh
- Department of Physical Therapy, HungKuang University, Taichung County, Taiwan, Republic of China
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Sanna F, Succu S, Boi A, Melis MR, Argiolas A. Phosphodiesterase type 5 inhibitors facilitate noncontact erections in male rats: site of action in the brain and mechanism of action. J Sex Med 2009; 6:2680-9. [PMID: 19678884 DOI: 10.1111/j.1743-6109.2009.01410.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
INTRODUCTION Orally active phosphodiesterase type 5 inhibitors (PDE5i), used in the treatment of erectile dysfunction, facilitate the relaxation of cavernous smooth muscle tissues by reducing the degradation of cyclic guanosine monophosphate. AIMS The aims of this article were to determine whether PDE5i facilitate penile erection and male sexual behavior by acting also on the central nervous system and to investigate their mechanism of action at central level. METHODS PDE5i (sildenafil, vardenafil, and tadalafil) given intraperitoneally (i.p.) (5 mg/kg and 10 mg/kg), intracerebroventricularly (i.c.v.) (10 microg and 50 microg), or into the ventral tegmental area (VTA) (10 microg) were tested in the noncontact erection test in male Sprague-Dawley rats screened for their ability to display or not display this sexual response. Extracellular dopamine was measured in the dialysate obtained from the nucleus accumbens by intracerebral microdialysis on injection of PDE5i into the VTA. MAIN OUTCOME MEASURES. Noncontact erections were counted after intraperitoneal, intracerebroventricular, or intra-VTA treatment with PDE5i. Extracellular dopamine was measured in the dialysate from the nucleus accumbens when sildenafil or vardenafil was given into the VTA. Results. PDE5i induced a significant increase of noncontact erections in male rats displaying this sexual response following intraperitoneal or intracerebroventricular administration at the highest dose tested. However, both doses significantly increased noncontact erections in male rats not displaying this sexual response. Similar results were found when PDE5i were injected into the caudal VTA. Noncontact erections increased concomitantly to a rise in extracellular dopamine in the dialysate from the nucleus accumbens. CONCLUSIONS The results suggest that PDE5i may increase sexual arousal by acting in the central nervous system. This effect may be mediated (at least in part) by the activation of mesolimbic dopaminergic neurons.
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Affiliation(s)
- Fabrizio Sanna
- Bernard B. Brodie Department of Neuroscience, University of Cagliari, Monserrato, Cagliari 09042, Italy
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Abstract
In recent years, considerable progress has been achieved in the comprehension of the profound effects of pheromones on reproductive physiology and behavior. Pheromones have been classified as molecules released by individuals and responsible for the elicitation of specific behavioral expressions in members of the same species. These signaling molecules, often chemically unrelated, are contained in body fluids like urine, sweat, specialized exocrine glands, and mucous secretions of genitals. The standard view of pheromone sensing was based on the assumption that most mammals have two separated olfactory systems with different functional roles: the main olfactory system for recognizing conventional odorant molecules and the vomeronasal system specifically dedicated to the detection of pheromones. However, recent studies have reexamined this traditional interpretation showing that both the main olfactory and the vomeronasal systems are actively involved in pheromonal communication. The current knowledge on the behavioral, physiological, and molecular aspects of pheromone detection in mammals is discussed in this review.
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Schober JM, Meyer-Bahlburg HFL, Dolezal C. Self-ratings of genital anatomy, sexual sensitivity and function in men using the 'Self-Assessment of Genital Anatomy and Sexual Function, Male' questionnaire. BJU Int 2009; 103:1096-103. [PMID: 19245445 DOI: 10.1111/j.1464-410x.2008.08166.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To assess the perceptions of healthy men of their genital anatomy and sexual sensitivity, along with the re-test reliability of these ratings, in a new self-reported questionnaire, the Self-Assessment of Genital Anatomy and Sexual Function, Male (SAGASF-M). SUBJECTS AND METHODS Eighty-one healthy, sexually active, men aged 22-57 years (median 33), with no history of genital surgery, completed the SAGASF-M. This questionnaire comprises written text and images enabling men to rate details of their genital appearance, overall genital erotic and pain sensitivity, orgasm intensity, and effort required for achieving orgasm through stimulation of specified areas around the glans and shaft of the penis, scrotum and anus, along with the contribution of other sexually sensitive areas of the body. Anatomical locations were compared for the functional ratings by mixed-model analysis of variance (anova). A second sample of 38 healthy men (median age 26 years, range 22-64) from the same source completed the SAGASF-M twice with an interval of 2 weeks. RESULTS There was little variability in anatomy ratings. Ratings of overall penile sensitivity to sexual stimulation gave higher values of 'sexual pleasure' for penile stimulation by the partner than by self (P = 0.002) and marginally higher ratings of 'orgasm intensity' by partner stimulation (P = 0.077), but there were no corresponding differences on ratings of 'effort needed to reach orgasm' or of 'discomfort/pain'. Overall discrimination between genital areas was highly significant (mixed-model anova, P = 0.001) for ratings of 'sexual pleasure', 'orgasm intensity' and 'orgasm effort', but was not significant for 'discomfort/pain'. Ranked by degree of 'sexual pleasure', the area 'underside of the glans' was highest, followed by 'underside of the penile shaft', 'upper side of the glans', 'left and right sides of the glans', 'one or both sides of the penis', 'upper side of the penile shaft', 'foreskin' (11 subjects), 'skin between the scrotum and anus', 'back side of the scrotum', 'front side of the scrotum', and 'around anus', but not all pair differences were significant. The rank order was similar for 'orgasm intensity', but less similar and with fewer significant pair differences for 'orgasm effort'. Overall discrimination of other body parts that help orgasm when touched/stimulated was also highly significant (P = 0.001) and included (in order of degree) scrotum, ear, skin between scrotum and anus, neck, breast/nipples, buttocks, anus (exterior skin), anus (inside with penetration), wrist, and axilla, but many pair differences were not significant. In the reliability study, which was limited to the 45 function items with sufficient variability and sample size, the re-test reliability values (Pearson r) were distributed as follows: seven were >or=0.80, 16 >or=0.70, 15 >or=0.60, four >or=0.50, two >or=0.40, and one >or=0.30. CONCLUSION The SAGASF-M discriminates reasonably well between various genital and nongenital areas in terms of erotic sensitivity, when administered to genitally unoperated men varying widely in age and socio-economic level.
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Rampin O, Jérôme N, Briant C, Boué F, Maurin Y. Are oestrus odours species specific? Behav Brain Res 2006; 172:169-72. [PMID: 16740322 DOI: 10.1016/j.bbr.2006.04.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2006] [Revised: 04/05/2006] [Accepted: 04/07/2006] [Indexed: 10/24/2022]
Abstract
Adult male rats were exposed to faeces odours of three animal species (rat, fox and horse). They displayed erections in the presence of faeces from oestrous females (whatever the species). In addition, fox faeces (whatever the gender or hormonal status) elicited an expected freezing reaction. It is suggested that oestrous female faeces of these three species share common odorants which depend on the hormonal status and characterize female receptivity.
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Affiliation(s)
- Olivier Rampin
- Analyse and Modélisation en Imagerie Biologique, NOPA, UMR 1197, Institut National de la Recherche Agronomique Université Paris Sud, Bât 325, F-78352 Jouy-en-Josas, France
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King BM. Amygdaloid lesion-induced obesity: relation to sexual behavior, olfaction, and the ventromedial hypothalamus. Am J Physiol Regul Integr Comp Physiol 2006; 291:R1201-14. [PMID: 16778067 DOI: 10.1152/ajpregu.00199.2006] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lesions of the amygdala have long been known to produce hyperphagia and obesity in cats, dogs, and monkeys, but only recently have studies with rats determined that the effective site is the posterodorsal amygdala (PDA)-the posterodorsal medial amygdaloid nucleus and the intra-amygdaloid bed nucleus of the stria terminalis. There is a sex difference; female rats with PDA lesions display greater weight gain than male rats. In the brains of female rats with obesity-inducing PDA lesions, there is a dense pattern of axonal degeneration in the capsule of the ventromedial hypothalamus (VMH) and other targets of the stria terminalis. Transections of the dorsal component of the stria terminalis also result in hyperphagia and obesity in female rats. Similar to rats with VMH lesions, rats with PDA lesions are hyperinsulinemic during food restriction and greatly prefer high-carbohydrate diets. The PDA is also a critical site for some aspects of rodent sexual behavior, particularly those that depend on olfaction, and the pattern of degeneration observed after obesity-inducing PDA lesions is remarkably parallel to the circuit that has been proposed to mediate sexual behavior. Medial amygdaloid lesions disrupt the normal feeding pattern and result in impaired responses to caloric challenges, and there is evidence that these behavioral changes are also due to a disruption of olfactory input. With its input from the olfactory bulbs and connections to the VMH, the PDA may be a nodal point at which olfactory and neuroendocrine stimuli are integrated to affect feeding behavior.
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Affiliation(s)
- Bruce M King
- Dept. of Psychology, Univ. of New Orleans, New Orleans, LA 70148, USA.
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Kondo Y, Sudo T, Tomihara K, Sakuma Y. Activation of accessory olfactory bulb neurons during copulatory behavior after deprivation of vomeronasal inputs in male rats. Brain Res 2003; 962:232-6. [PMID: 12543475 DOI: 10.1016/s0006-8993(02)03970-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
We examined whether the vomeronasal organ (VNO) is the sole receptor for pheromonal cues for male sexual behavior. Males carrying surgical removal of the VNO (VNOx) mated with stimulus females as sham-operated males, with a comparable number of mounts but a prolonged latency for ejaculation. In sham-operated males, mating increased cFos immunoreactivity in the granule and mitral cell layers of the accessory olfactory bulb and in the medial amygdala. VNOx diminished baseline as well as mating-induced cFos in the granule cell layer and in the medial amygdala; VNOx had no effect on either basal or induced cFos immunoreactivity in the mitral cell layer. Thus, during mating encounter, cFos expression in the mitral cell layer did not depend on VNO inputs. The medial amygdala may be modulated by impulses other than of mitral cell origin.
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Affiliation(s)
- Yasuhiko Kondo
- Department of Physiology, Nippon Medical School, Sendagi 1, Bunkyo, Tokyo 113-8602, Japan.
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21
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Abstract
Sexual experience facilitates subsequent male sexual behavior; activation of the N-methyl-D-aspartate (NMDA) glutamate receptor may play a role in this experience-induced enhancement. In this article, the authors report that systemic injections of MK-801, an NMDA receptor antagonist, impaired male sexual behavior in sexually naive and sexually experienced male rats. Furthermore, saline-treated rats that received 7 daily exposures to an inaccessible estrous female instead of sexual experience displayed enhancement of copulation on the following day. Injections of MK-801 before each of these exposures inhibited the experience-induced enhancement on the drug-free test on Day 8. These data suggest that stimulation of NMDA receptors enhances sexual performance immediately and mediates the experience-induced enhancement of subsequent copulatory behavior.
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Affiliation(s)
- Whitney S Powell
- Department of Psychology, University at Buffalo, The State University of New York, 14260, USA
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22
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Abstract
Castration of male rats causes a rapid loss of their normal erectile response to inaccessible estrous females. Previous studies had demonstrated that these noncontact erections (NCEs), a putative sign of sexual arousal, could be restored by systemic treatment with testosterone (T) or dihydrotestosterone (DHT), but not estradiol (E). We examined whether androgen delivered to the medial amygdala (MeA) of castrated rats would maintain NCE. In Experiment 1, males received bilateral cannulae filled with T, DHT, or E directed at the MeA. Control males had the same hormone-filled cannulae implanted subcutaneously and blank cannulae in the MeA, or they received T in the anterior forebrain. During the 2 weeks after surgery, males were tested twice for NCE and copulation. About half the males with androgens in the MeA had NCEs 1 week after castration, but few responded a week later. Closer proximity of androgen implants to the posterodorsal MeA (MeApd) predicted shorter NCE latencies. No males with subcutaneous androgen had NCEs in either test, and few anterior forebrain-implanted males did. Some males receiving E in MeA or subcutaneously had NCE in each test. In copulation tests, the type of steroid treatment did not affect the incidence of ejaculation or most measures of copulation, and the proximity of cannulae to MeApd predicted only the time from ejaculation to the occurrence of NCE during the postejaculatory interval. Experiment 2 showed that NCEs displayed by males with androgen in MeA occurred in response to estrous females, not spontaneously. The results suggest that androgens, perhaps augmented by estrogen, act in the posterodorsal MeA to facilitate NCE and its associated arousal.
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Affiliation(s)
- Michal Bialy
- Department of Experimental and Clinical Physiology, Medical University of Warsaw, 00-927, Warsaw, Poland.
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23
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Abstract
Male rats with radiofrequency lesions in the anterior medial amygdala (MeAa) or the posterior medial amygdala (MeAp), respectively, were tested for copulation and for noncontact erection (NCE; evoked by inaccessible estrous females) in a chamber in which the male was located between estrous and anestrous females. Barriers allowed only olfactory and auditory interaction between animals. With conscious females as stimuli, MeAp lesions virtually eliminated NCEs, and MeAa lesions moderately impaired them, without affecting the normal preference for estrous over anestrous females. When tested with anesthetized females to remove auditory stimulation, few males with lesions had NCEs. Only the males with MeAp lesions had a significant reduction in preference for estrous over anestrous anesthetized females. Neither MeAa nor MeAp lesions had an effect on copulatory behavior. MeAp lesions may have caused a reduced sensitivity to--or impaired processing of--estrous odors, thereby preventing NCE without disrupting copulatory behavior.
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Affiliation(s)
- Yasuhiko Kondo
- Department of Psychology, University of Connecticut, Storrs, CT, USA.
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Abstract
Sexually experienced Wistar male rats were used to investigate (a) urine voiding in the presence of nearby estrous females and the control of such voiding by (b) steroid hormones and (c) peripheral nerves supplying the genitourinary system. The first experiment showed that males always have a low rate of urine voiding that is significantly increased when a receptive female is around. Thus, it is suggested that an airborne scent from the female stimulates the olfactory system of males, triggering urine emission to transmit sex-related messages, i.e., male rats display the well-known urine-marking behavior of mammals. The number of urine marks and sniffing to females decreased after castration, and were restored after exogenous treatment with testosterone or estradiol. The proposed hypothesis is that airborne scents from the female activate the aromatization process in nuclei of the olfactory pathway of the male, evoking a cascade of neuronal responses that finish in urine marking. Peripheral nerves supplying the genitourinary system are the viscerocutaneous branch of the pelvic nerve (Vc) and the hypogastric (Hg). Data showed that both nerves are important for the central control of urine storage and voiding. Transection of Vc almost blocked urine marking, while Hg lesion increased the number of marks. Thus, it is discussed that Vc is the most important nerve in charge of voiding the bladder, and that Hg is important for continence.
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Affiliation(s)
- J Manzo
- Instituto de Neuroetología, Universidad Veracruzana, Apartado Postal 566, Xalapa, Ver. 91001, Mexico.
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Swann J, Rahaman F, Bijak T, Fiber J. The main olfactory system mediates pheromone-induced fos expression in the extended amygdala and preoptic area of the male Syrian hamster. Neuroscience 2001; 105:695-706. [PMID: 11516834 DOI: 10.1016/s0306-4522(01)00227-5] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Copulation in male hamsters is stimulated by exposure to vaginal secretions of conspecifics. These pheromones also stimulate fos expression in neural areas that regulate copulation including: the medial nucleus of the amygdala, the bed nucleus of the stria terminalis, and the preoptic area. The pheromones in vaginal secretions are detected by both the main and accessory olfactory systems. However, the accessory system plays the greater role in the regulation of mating behavior and has direct connections with the medial nucleus of the amygdala and bed nucleus of the stria terminalis. The goal of the present study was to determine which system mediates the effect of pheromones on the stimulation of more central areas by deafferenting these systems in experienced male hamsters before exposure to vaginal secretions. Destruction of the receptors in the main olfactory system with zinc sulfate eliminated the increase in fos immunoreactivity in the amygdala, bed nucleus of the stria terminalis and preoptic area following exposure to sexually stimulating pheromones. Deafferentation of the accessory olfactory system by removing the vomeronasal organ had no effect on pheromone-induced fos expression in these areas. We conclude that neurons expressing fos following exposure to vaginal secretions are stimulated via the main olfactory system and are not associated with the expression of copulatory behavior.
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Affiliation(s)
- J Swann
- Department of Biological Sciences, Rutgers University, Newark, NJ 07102, USA.
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