Induction of mammary secretion by hypothalamic lesions in male rats.

Abstract

Hypothalamic lesions in the median eminence (ME), hypophysial stalk, or paraventricular nuclei of male rats produced lobulo-alveolar development and secretion in the mammae. Lesions in the preoptic area and mamillary bodies were ineffective. The time course of these mammary changes was followed in rats with ME or stalk lesions. Mammary development and secretion was apparent at 2 days and reached a maximum at 4 days postoperatively. By 17 days the mammae had regressed to an atrophic condition. At this time weights of testes, seminal vesicles and adrenals were subnormal. The mammary changes seen in rats with hypothalamic lesions could be mimicked by the administration of a total dose of 5.0 or more IU of prolactin in 5 subcutaneous (sc) injections spaced over a 48-hr period. Adrenalectomy performed just prior to placement of ME lesions did not interfere with the development of mammary changes. Castration 7 days prior to location of ME lesions prevented the development of the mammary changes unless the rats ...