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Oti T, Satoh K, Uta D, Nagafuchi J, Tateishi S, Ueda R, Takanami K, Young LJ, Galione A, Morris JF, Sakamoto T, Sakamoto H. Oxytocin Influences Male Sexual Activity via Non-synaptic Axonal Release in the Spinal Cord. Curr Biol 2020; 31:103-114.e5. [PMID: 33125871 DOI: 10.1016/j.cub.2020.09.089] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 01/21/2020] [Accepted: 09/29/2020] [Indexed: 01/15/2023]
Abstract
Oxytocinergic neurons in the paraventricular nucleus of the hypothalamus that project to extrahypothalamic brain areas and the lumbar spinal cord play an important role in the control of erectile function and male sexual behavior in mammals. 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)." We have examined the functional interaction between the SEG neurons and the hypothalamo-spinal oxytocin system in rats. Here, we show that SEG/GRP neurons express oxytocin receptors and are activated by oxytocin during male sexual behavior. Intrathecal injection of oxytocin receptor antagonist not only attenuates ejaculation but also affects pre-ejaculatory behavior during normal sexual activity. Electron microscopy of potassium-stimulated acute slices of the lumbar cord showed that oxytocin-neurophysin-immunoreactivity was detected in large numbers of neurosecretory dense-cored vesicles, many of which are located close to the plasmalemma of axonal varicosities in which no electron-lucent microvesicles or synaptic membrane thickenings were visible. These results suggested that, in rats, release of oxytocin in the lumbar spinal cord is not limited to conventional synapses but occurs by exocytosis of the dense-cored vesicles from axonal varicosities and acts by diffusion-a localized volume transmission-to reach oxytocin receptors on GRP neurons and facilitate male sexual function.
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Affiliation(s)
- Takumi Oti
- Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, Ushimado, Setouchi, Okayama 701-4303, Japan; Department of Biological Sciences, Faculty of Science, Kanagawa University, Hiratsuka, Kanagawa 259-1293, Japan
| | - Keita Satoh
- Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, Ushimado, Setouchi, Okayama 701-4303, Japan; Department of Anatomy, Kawasaki Medical School, Kurashiki, Okayama 701-0192, Japan
| | - Daisuke Uta
- Department of Applied Pharmacology, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-0194, Japan
| | - Junta Nagafuchi
- Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, Ushimado, Setouchi, Okayama 701-4303, Japan
| | - Sayaka Tateishi
- Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, Ushimado, Setouchi, Okayama 701-4303, Japan; Department of Biology, Faculty of Science, Okayama University, 3-1-1 Kita-ku, Tsushimanaka, Okayama 700-8530, Japan
| | - Ryota Ueda
- Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, Ushimado, Setouchi, Okayama 701-4303, Japan; Department of Biology, Faculty of Science, Okayama University, 3-1-1 Kita-ku, Tsushimanaka, Okayama 700-8530, Japan
| | - Keiko Takanami
- Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, Ushimado, Setouchi, Okayama 701-4303, Japan; Mouse Genomics Resources Laboratory, National Institute of Genetics, Yata, Mishima, Shizuoka 411-8540, Japan
| | - Larry J Young
- Center for Translational Social Neuroscience, Silvio O. Conte Center for Oxytocin and Social Cognition, Department of Psychiatry and Behavioral Sciences, Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA; Center for Social Neural Networks, University of Tsukuba, Tsukuba 305-8577, Japan
| | - Antony Galione
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
| | - John F Morris
- Department of Physiology, Anatomy & Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK
| | - Tatsuya Sakamoto
- Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, Ushimado, Setouchi, Okayama 701-4303, Japan
| | - Hirotaka Sakamoto
- Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, Ushimado, Setouchi, Okayama 701-4303, Japan; Department of Physiology, Anatomy & Genetics, University of Oxford, South Parks Road, Oxford OX1 3QX, UK.
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