unraveling-role-discrete-areas-rat-brain-regulation-ovulation-through

Unraveling the Role of Discrete Areas of the Rat Brain in the Regulation of Ovulation through Reversible Inactivation by Tetrodotoxin Microinjections

Many experimental approaches have been used for studying the role of the brain in the regulation of ovulation. Examples include the lesion and ...

Universidad Nacional Autónoma de México

What is the central question of this study? Is the suprachiasmatic nucleus the structure that generates the neural circadian signals that occur during every stage of the oestrous cycle, not only pro-oestrus, and are these signals essential for proper regulation of ovulation? What is the main finding and its importance? Transient inhibition of Na -dependent action potentials in the suprachiasmatic nucleus by tetrodotoxin microinjection at 14.00 h inhibits ovulation irrespective of the stage of the oestrous cycle at which the procedure is performed. Microinjection of saline solution into the suprachiasmatic nucleus has a disruptive effect on ovulation that depends on the stage of the cycle at which it is administered.

A neural circadian signal essential for ovulation is generated in the suprachiasmatic nucleus during each stage of the oestrous cycle.

Several aspects of the physiology and behavior of organisms are expressed rhythmically with a 24-h periodicity and hence called circadian rhythms. Such rhythms are thought to be an adaptive response that allows to anticipate cyclic events in the environment. In mammals, the circadian system is a hierarchically organized net of endogenous oscillators driven by the hypothalamic suprachiasmatic nucleus (SCN). This system is synchronized by the environment throughout afferent pathways and in turn it organizes the activity of tissues by means of humoral secretions and neuronal projections. It has been shown that reproductive cycles are regulated by the circadian system. In rodents, the lesion of the SCN results on alterations of the estrous cycle, sexual behavior, tonic and phasic secretion of gonadotropin releasing hormone (GnRH)/gonadotropins and in the failure of ovulation. Most of the studies regarding the circadian control of reproduction, in particular of ovulation, have only focused on the participation of the SCN in the triggering of the proestrus surge of gonadotropins. Here we review aspects of the evolution and organization of the circadian system with particular focus on its relationship with the reproductive cycle of laboratory rodents. Experimental evidence of circadian control of neuroendocrine events indispensable for ovulation that occur prior to proestrus are discussed. In order to offer a working model of the circadian regulation of reproduction, its participation on aspects ranging from gamete production, neuroendocrine regulation, sexual behavior, mating coordination, pregnancy and deliver of the product should be assessed experimentally.

Article	Year
A neural circadian signal essential for ovulation is generated in the suprachiasmatic nucleus during each stage of the oestrous cycle. Experimental physiology\| PubMed ID: 31769118	2020
Clock control of mammalian reproductive cycles: Looking beyond the pre-ovulatory surge of gonadotropins. Reviews in endocrine & metabolic disorders\| PubMed ID: 31828563	2020

Carlos-Camilo Silva

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