Stimulation of the hypothalamus and ovulation in the guinea-pig.

1. Various methods of stimulating the hypothalamus were applied to the guinea-pig with the aim of inducing ovulation.2. Electrochemical stimulation of the hypothalamus, or gross stimulation of the brain, was ineffective.3. Electrical stimulation of the medial basal hypothalamus or rostral hypothalamus elicited gonadotrophin release.4. Despite variation of the time and intensity of stimulation, follicular luteinization was more common than the formation of new corpora lutea.5. Electrical stimulation of the medial basal hypothalamus often caused luteinization of follicles. Fewer animals responded to excitation of the rostral hypothalamus, but in those that did, ovulation occurred more frequently.6. The present observations contrast markedly with comparable studies on the rat, where both electrochemical and electrical stimulation of the hypothalamus readily induce ovulation.