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Oti T, Sakamoto H. Neuropeptidergic control circuits in the spinal cord for male sexual behaviour: Oxytocin-gastrin-releasing peptide systems. J Neuroendocrinol 2023; 35:e13324. [PMID: 37515539 DOI: 10.1111/jne.13324] [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: 12/31/2022] [Revised: 06/30/2023] [Accepted: 07/08/2023] [Indexed: 07/31/2023]
Abstract
The neuropeptidergic mechanisms controlling socio-sexual behaviours consist of complex neuronal circuitry systems in widely distributed areas of the brain and spinal cord. At the organismal level, it is now becoming clear that "hormonal regulations" play an important role, in addition to the activation of neuronal circuits. The gastrin-releasing peptide (GRP) system in the lumbosacral spinal cord is an important component of the neural circuits that control penile reflexes in rats, circuits that are commonly referred to as the "spinal ejaculation generator (SEG)." Oxytocin, long known as a neurohypophyseal hormone, is now known to be involved in the regulation of socio-sexual behaviors in mammals, ranging from social bonding to empathy. However, the functional interaction between the SEG neurons and the hypothalamo-spinal oxytocin system remains unclear. Oxytocin is known to be synthesised mainly in hypothalamic neurons and released from the posterior pituitary into the circulation. Oxytocin is also released from the dendrites of the neurons into the hypothalamus where they have important roles in social behaviours via non-synaptic volume transmission. Because the most familiar functions of oxytocin are to regulate female reproductive functions including parturition, milk ejection, and maternal behaviour, oxytocin is often thought of as a "feminine" hormone. However, there is evidence that a group of parvocellular oxytocin neurons project to the lower spinal cord and control male sexual function in rats. In this report, we review the functional interaction between the SEG neurons and the hypothalamo-spinal oxytocin system and effects of these neuropeptides on male sexual behaviour. Furthermore, we discuss the finding of a recently identified, localised "volume transmission" role of oxytocin in the spinal cord. Findings from our studies suggest that the newly discovered "oxytocin-mediated spinal control of male sexual function" may be useful in the treatment of erectile and ejaculatory dysfunction.
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Affiliation(s)
- Takumi Oti
- Department of Biological Sciences, Faculty of Science, Kanagawa University, Hiratsuka, Japan
- Ushimado Marine Institute (UMI), Faculty of Environmental, Life, Natural Science and Technology, Okayama University, Okayama, Japan
| | - Hirotaka Sakamoto
- Ushimado Marine Institute (UMI), Faculty of Environmental, Life, Natural Science and Technology, Okayama University, Okayama, Japan
- Department of Biology, Faculty of Environmental, Life, Natural Science and Technology, Okayama University, Okayama, Japan
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Takanami K, Oti T, Kobayashi Y, Hasegawa K, Ito T, Tsutsui N, Ueda Y, Carstens E, Sakamoto T, Sakamoto H. Characterization of the expression of gastrin-releasing peptide and its receptor in the trigeminal and spinal somatosensory systems of Japanese macaque monkeys: Insight into humans. J Comp Neurol 2022; 530:2804-2819. [PMID: 35686563 DOI: 10.1002/cne.25376] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2021] [Revised: 05/16/2022] [Accepted: 05/18/2022] [Indexed: 11/06/2022]
Abstract
Gastrin-releasing peptide (GRP) and its receptor (GRPR) have been identified as itch mediators in the spinal and trigeminal somatosensory systems in rodents. In primates, there are few reports of GRP/GRPR expression or function in the spinal sensory system and virtually nothing is known in the trigeminal system. The aim of the present study was to characterize GRP and GRPR in the trigeminal and spinal somatosensory system of Japanese macaque monkeys (Macaca fuscata). cDNA encoding GRP was isolated from the macaque dorsal root ganglion (DRG) and exhibited an amino acid sequence that was highly conserved among mammals and especially in primates. Immunohistochemical analysis demonstrated that GRP was expressed mainly in the small-sized trigeminal ganglion and DRG in adult macaque monkeys. Densely stained GRP-immunoreactive (ir) fibers were observed in superficial layers of the spinal trigeminal nucleus caudalis (Sp5C) and the spinal cord. In contrast, GRP-ir fibers were rarely observed in the principal sensory trigeminal nucleus and oral and interpolar divisions of the spinal trigeminal nucleus. cDNA cloning, in situ hybridization, and Western blot revealed substantial expression of GRPR mRNA and GRPR protein in the macaque spinal dorsal horn and Sp5C. Our Western ligand blot and ligand derivative stain for GRPR revealed that GRP directly bound in the macaque Sp5C and spinal dorsal horn as reported in rodents. Finally, GRP-ir fibers were also detected in the human spinal dorsal horn. The spinal and trigeminal itch neural circuits labeled with GRP and GRPR appear to function also in primates.
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Affiliation(s)
- Keiko Takanami
- Ushimado Marine Institute (UMI), Okayama University, Okayama, Japan.,Department of Genetics, Mouse Genomics Resources Laboratory, National Institute of Genetics, Sokendai (The Graduate University for Advanced Studies), Shizuoka, Japan.,Department of Anatomy and Neurobiology, Kyoto Prefectural University of Medicine, Kyoto, Japan.,Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California, USA
| | - Takumi Oti
- Ushimado Marine Institute (UMI), Okayama University, Okayama, Japan.,Department of Biological Sciences, Faculty of Science, Kanagawa University, Kanagawa, Japan
| | - Yasuhisa Kobayashi
- Ushimado Marine Institute (UMI), Okayama University, Okayama, Japan.,Department of Aquatic Biology, Fisheries, Faculty of Agriculture, Kindai University, Nara, Japan
| | - Koki Hasegawa
- Center for Instrumental Analysis, Kyoto Pharmaceutical University, Kyoto, Japan.,Theranostic Pharmaceuticals Laboratory, Department of Radiological Sciences, School of Health Sciences, Fukushima Medical University, Fukushima, Japan
| | - Takashi Ito
- Ushimado Marine Institute (UMI), Okayama University, Okayama, Japan
| | - Naoaki Tsutsui
- Ushimado Marine Institute (UMI), Okayama University, Okayama, Japan.,Department of Marine Bioresources, Mie University, Mie, Japan
| | - Yasumasa Ueda
- Department of Physiology, Kyoto Prefectural University of Medicine, Kyoto, Japan.,Department of Physiology, Kansai Medical University, Osaka, Japan
| | - Earl Carstens
- Department of Neurobiology, Physiology, and Behavior, University of California, Davis, California, USA
| | - Tatsuya Sakamoto
- Ushimado Marine Institute (UMI), Okayama University, Okayama, Japan
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Wang G, Shen D, Zhang X, Ferrini MG, Li Y, Liao H. Comparison of critical biomarkers in 2 erectile dysfunction models based on GEO and NOS-cGMP-PDE5 pathway. Medicine (Baltimore) 2021; 100:e27508. [PMID: 34731136 PMCID: PMC8519209 DOI: 10.1097/md.0000000000027508] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 09/25/2021] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Erectile dysfunction is a disease commonly caused by diabetes mellitus (DMED) and cavernous nerve injury (CNIED). Bioinformatics analyses including differentially expressed genes (DEGs), enriched functions and pathways (EFPs), and protein-protein interaction (PPI) networks were carried out in DMED and CNIED rats in this study. The critical biomarkers that may intervene in nitric oxide synthase (NOS, predominantly nNOS, ancillary eNOS, and iNOS)-cyclic guanosine monophosphate (cGMP)-phosphodiesterase 5 enzyme (PDE5) pathway, an important mechanism in erectile dysfunction treatment, were then explored for potential clinical applications. METHODS GSE2457 and GSE31247 were downloaded. Their DEGs with a |logFC (fold change)| > 0 were screened out. Database for Annotation, Visualization and Integrated Discovery (DAVID) online database was used to analyze the EFPs in Gene Ontology enrichment and Kyoto Encyclopedia of Genes and Genomes networks based on down-regulated and up-regulated DEGs respectively. PPI analysis of 2 datasets was performed in Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) and Cytoscape. Interactions with an average score greater than 0.9 were chosen as the cutoff for statistical significance. RESULTS From a total of 1710 DEGs in GSE2457, 772 were down-regulated and 938 were up-regulated, in contrast to the 836 DEGs in GSE31247, from which 508 were down-regulated and 328 were up-regulated. The 25 common EFPs such as aging and response to hormone were identified in both models. PPI results showed that the first 10 hub genes in DMED were all different from those in CNIED. CONCLUSIONS The intervention of iNOS with the hub gene complement component 3 in DMED and the aging process in both DMED and CNIED deserves attention.
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Affiliation(s)
- Guangying Wang
- Department of Pharmacy, Shanxi Provincial People's Hospital of Shanxi Medical University, Taiyuan, China
| | - Dayue Shen
- School of Pharmacy, Shanxi Medical University, Taiyuan, China
| | - Xilan Zhang
- School of Pharmacy, Shanxi Medical University, Taiyuan, China
| | - Monica G. Ferrini
- Department of Health and Life Sciences & Department of Internal Medicine, Charles R. Drew University, Los Angeles, CA
- Department of Medicine, David Geffen School of Medicine at UCLA, Los Angeles, CA
| | - Yuanping Li
- Department of Pharmacy, Shanxi Provincial People's Hospital of Shanxi Medical University, Taiyuan, China
| | - Hui Liao
- Department of Pharmacy, Shanxi Provincial People's Hospital of Shanxi Medical University, Taiyuan, China
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Sexual Experience Induces the Expression of Gastrin-Releasing Peptide and Oxytocin Receptors in the Spinal Ejaculation Generator in Rats. Int J Mol Sci 2021; 22:ijms221910362. [PMID: 34638701 PMCID: PMC8508609 DOI: 10.3390/ijms221910362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 09/01/2021] [Accepted: 09/23/2021] [Indexed: 01/04/2023] Open
Abstract
Male sexual function in mammals is controlled by the brain neural circuits and the spinal cord centers located in the lamina X of the lumbar spinal cord (L3–L4). Recently, we reported that hypothalamic oxytocin neurons project to the lumbar spinal cord to activate the neurons located in the dorsal lamina X of the lumbar spinal cord (dXL) via oxytocin receptors, thereby facilitating male sexual activity. Sexual experiences can influence male sexual activity in rats. However, how this experience affects the brain–spinal cord neural circuits underlying male sexual activity remains unknown. Focusing on dXL neurons that are innervated by hypothalamic oxytocinergic neurons controlling male sexual function, we examined whether sexual experience affects such neural circuits. We found that >50% of dXL neurons were activated in the first ejaculation group and ~30% in the control and intromission groups in sexually naïve males. In contrast, in sexually experienced males, ~50% of dXL neurons were activated in both the intromission and ejaculation groups, compared to ~30% in the control group. Furthermore, sexual experience induced expressions of gastrin-releasing peptide and oxytocin receptors in the lumbar spinal cord. This is the first demonstration of the effects of sexual experience on molecular expressions in the neural circuits controlling male sexual activity in the spinal cord.
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Oti T, Sakamoto T, Sakamoto H. Systemic effects of oxytocin on male sexual activity via the spinal ejaculation generator in rats. Commun Integr Biol 2021; 14:55-60. [PMID: 33828638 PMCID: PMC8009111 DOI: 10.1080/19420889.2021.1902056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Oxytocin is produced in the hypothalamus and stimulates uterine contraction and milk ejection. While many people consider oxytocin to be a female hormone, it is reported that, in men, the plasma oxytocin level increases markedly after ejaculation. However, this aspect of oxytocin physiology is poorly understood. The spinal ejaculation generator (SEG), which expresses the neuropeptide, gastrin-releasing peptide (GRP), can trigger ejaculation in rats. Therefore, we focused on systemic effects of oxytocin on the GRP/SEG neuron system in the lumbar spinal cord controlling sexual activity in male rats. We found that systemic administration of oxytocin significantly shortened the latency to the first mount, intromission and ejaculation during male copulatory behavior. In addition, the local oxytocin level in the lumbar cord was significantly higher in males than in females. Histological analysis showed that oxytocin-binding is apparent in spinal GRP/SEG neurons. We therefore conclude that oxytocin influences male sexual activity via the SEG.
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Affiliation(s)
- Takumi Oti
- Department of Biological Sciences, Faculty of Science, Kanagawa University, Hiratsuka, Japan.,Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, Setouchi, Japan
| | - Tatsuya Sakamoto
- Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, Setouchi, Japan
| | - Hirotaka Sakamoto
- Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, Setouchi, Japan
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Oti T, Takanami K, Ito S, Ueda T, Matsuda KI, Kawata M, Soh J, Ukimura O, Sakamoto T, Sakamoto H. Effects of Sex Steroids on the Spinal Gastrin-Releasing Peptide System Controlling Male Sexual Function in Rats. Endocrinology 2018. [PMID: 29534195 DOI: 10.1210/en.2018-00043] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The gastrin-releasing peptide (GRP) system in the lumbosacral spinal cord controls male sexual function in rats. In contrast, in female rats, GRP neurons could scarcely be detected around puberty when circulating ovarian steroid hormones such as estradiol and progesterone levels are increasing. However, little information is available on feminizing or demasculinizing effects of ovarian steroids on the central nervous system in female puberty and adulthood. In this study, to visualize the spinal GRP neurons in vivo, we generated a GRP-promoter-Venus transgenic (Tg) rat line and studied the effects of the sex steroid hormones on GRP expression in the rat lumbar cord by examining the Venus fluorescence. In these Tg rats, the sexually dimorphic spinal GRP neurons controlling male sexual function were clearly labeled with Venus fluorescence. As expected, Venus fluorescence in the male lumbar cord was markedly decreased after castration and restored by chronic androgen replacement. Furthermore, androgen-induced Venus expression in the spinal cord of adult Tg males was significantly attenuated by chronic treatment with progesterone but not with estradiol. A luciferase assay using a human GRP-promoter construct showed that androgens enhance the spinal GRP system, and more strikingly, that progesterone acts to inhibit the GRP system via an androgen receptor-mediated mechanism. These results demonstrate that circulating androgens may play an important role in the spinal GRP system controlling male sexual function not only in rats but also in humans and that progesterone could be an important feminizing factor in the spinal GRP system in females during pubertal development.
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Affiliation(s)
- Takumi Oti
- Ushimado Marine Institute, Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan
| | - Keiko Takanami
- Ushimado Marine Institute, Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan
- Department of Anatomy and Neurobiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Saya Ito
- Department of Urology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Takashi Ueda
- Department of Urology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Ken Ichi Matsuda
- Department of Anatomy and Neurobiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Mitsuhiro Kawata
- Department of Anatomy and Neurobiology, Kyoto Prefectural University of Medicine, Kyoto, Japan
- Department of Physical Therapy, School of Health Sciences, Bukkyo University, Kyoto, Japan
| | - Jintetsu Soh
- Department of Urology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Osamu Ukimura
- Department of Urology, Kyoto Prefectural University of Medicine, Kyoto, Japan
| | - Tatsuya Sakamoto
- Ushimado Marine Institute, Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan
| | - Hirotaka Sakamoto
- Ushimado Marine Institute, Graduate School of Natural Science and Technology, Okayama University, Okayama, Japan
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