Brain Nuclei in the Regulation of Sexual Behavior, Peripheral Nerves Related to Reproduction, and Their Alterations in Neurodegenerative Diseases: A Brief Review

Sexual behavior is a complex process in which the brain plays an active role. In the male rat, stimuli from the female are perceived through sensory receptors related to olfaction, hearing, vision, and the perigenital area, priming the individual for a sexual response. This process culminates with ejaculation and the deposition of semen into the uterine tract with the aim of achieving fertilization. The brain plays a fundamental role in both generating motivation and executing male sexual behavior. Meanwhile, the spinal cord, through the autonomic nervous system and the pelvic ganglion, transmits information to the reproductive organs, including the testes. Currently, there is extensive evidence demonstrating the involvement of various brain structures in the regulation of sexual behavior, as well as specific regions of the spinal cord involved in the control of ejaculation. For instance, the medial preoptic area (MPOA) has been shown to regulate the secretion of pituitary hormones, which in turn modulate the function of reproductive organs. Among these, testosterone production is particularly notable, as this hormone not only directly affects reproductive organs but also exerts a modulatory role on brain nuclei responsible for sexual behavior. Although there is a reciprocal regulation between the nervous and endocrine systems, it is important to note that the execution of sexual behavior also impacts peripheral structures, such as the major pelvic ganglion (MPG) and the testis, preparing the organism for reproduction. The purpose of this mini-review is to provide an overview of the main brain nuclei involved in the regulation of sexual behavior, as well as the spinal cord regions implicated in reproduction. Finally, we discuss how these structures may alter their function in the context of neurodegenerative diseases, aiming to introduce readers to this field of study.