Pineal regulation of immunoreactive luteinizing hormone and prolactin in light deprived female hamsters

The binding of adult female hamsters caused atrophy of the reproductive organs, an increased level of luteinizing hormone (LH), and a decreased level of prolactin in the anterior pituitary gland. Each of these effects in blinded hamsters was reversed by pinealectomy or by superior cervical ganglionectomy, a procedure which sympathetically denervates the pineal gland. Chronic subcutaneous injections (2 μg twice daily for 1 wk) of synthetic luteinizing hormone releasing hormone caused a release of pituitary LH as evidenced by the increased level of this gonadotropin in the plasma. LH RH had no apparent influence on plasma prolactin titers or on the secretion of follicle stimulating hormone.