The effects of ciliary neurotrophic factor on the hypothalamo-pituitary gonadal axis in vitro in female rats

Ciliary neurotrophic factor (CNTF) is a member of the neuropoietic family o f cytokines. CNTF exerts its actions through activation of a receptor compl ex, which shows similarity of sequence, second messenger systems and distri bution to the leptin receptor. Leptin has been demonstrated to exert profou nd effects on the hypothalamo-pituitary gonadal axis. This study examines t he in vitro effects of CNTF on hypothalamic luteinizing hormone releasing h ormone release (LHRH) and pituitary luteinizing hormone (LH) release compar ed to those of leptin in the female. We report that CNTF stimulates LHRH re lease from medial basal hypothalamic explants harvested from proestrous fem ale rats and this effect is of similar magnitude to that seen with leptin. In contrast, CNTF suppresses LHRH-stimulated LH release from dispersed ante rior pituitary cells harvested from proestrous female rats but has no effec t on basal LH release. Leptin stimulates basal LH release but has no effect on LHRH-stimulated LH release. The suppressive effect of CNTF on LHRH-stim ulated LH release has been confirmed in perifused anterior hemipituitaries. These results suggest a differential effect of CNTF on the hypothalamo-pit uitary gonadal axis and a possible role in the modulation of pituitary gona dal function.