Central Neural Control of Spontaneous Ovulation: The Rat Model
The facts that both steroid-induced and spontaneous ovulation in rats can be prevented by treatment with centrally acting drugs and that the controls exhibit circadian rhythmicity implied participation of the central nervous system. Neural control was also implied indirectly by the report by Dempsey and Searles (1943) that LLPE rats formed corpora lutea after copulation. In the estrous rabbit and cat, several workers induced ovulation by electrical stimulation of the hypothalamus or the amygdala (see Harris 1972). Yet not until 1957 was there comparable direct evidence of a role of the brain in species that ovulate spontaneously. In that year Bunn and Everett reported ovulation induced in alert LLPE rats by electrical stimulation through electrodes chronically implanted in the amygdala or septum pellucidum. Critchlow (1957, 1958), employing cyclic rats anesthetized with pentobarbital during the proestrus critical period, succeeded in inducing ovulation by stimulation through electrodes stereotaxically placed deep in the medial hypothalamus. Since then the pentobarbital-blocked rat has become a favorite experimental subject in this and other laboratories.
KeywordsElectrical Stimulation Prussian Blue Anterior Commissure Pulse Pair Medial Preoptic Area
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