Effect of stimulation or lesioning of the hypothalamus upon gonadotrophin secretion in the guinea-pig.

The effect of electrical stimulation of the anterior hypothalamus of the guinea-pig upon follicle-stimulating hormone (FSH) and luteinizing hormone (LH) secretion during two phases of the oestrous cycle was examined and compared with the response to electrolytic or radio-frequency lesions placed in the same area. The secretion of LH was briefly increased by electrical stimulation of the hypothalamus, with a greater response occurring over days 7-8 (luteal phase) of the oestrous cycle than on days 13-14 (follicular phase). An equivalent rise in LH output was produced by placement of direct current (d.c.) lesions in the hypothalamus, whereas lesions made with radio-frequency current produced a small increase only on days 13-14. The secretion of FSH was not changed by any procedure.