Lesions of the sexually dimorphic nucleus of the preoptic area: effects upon LH, FSH and prolactin in rats

Bilateral lesions were placed in the sexually dimorphic nucleus of the preoptic area (SDN-POA) in castrated adult male rats in an attempt to determine a physiologic role for this nucleus. These lesions significantly attenuated the increase in plasma FSH and LH due to simultaneous castration at 24 hr, and at 7 and 14 days following surgery, and significantly decreased the levels of plasma prolactin on comparison with pre-operative values and those of castrated controls. When rats were castrated and lesions placed at 14 days following castration, plasma levels of FSH, LH and prolactin were significantly decreased at 24 hr and at 7 days following surgery. Lesions which were placed lateral or caudal to the SDN-POA simulated the effects of lesions placed within the SDN-POA upon plasma LH, FSH and prolactin, with lateral lesions being most effective. However, lesions which were placed dorsal or rostral to the SDN-POA had no effect. The results of these studies suggest that the SDN-POA may be involved in the regulation of LH, FSH, and prolactin release.