[Luteinizing hormone content in the pineal body depending on the physiological state of rats]

The changes in the luteinizing hormone (LH) level in the pineal gland were studied in rats depending on their sex and age, and under conditions of hypophysectomy or gonadectomy. In golden hamsters these changes were studied during the sexual cycle. The LH level was determined by the radioimmunological method. The gonadotropin content in animals aged under 15 days was independent of sex. At the age of 23 days the LH content was greater in the female animals than in the male, whereas in 30- and 60-day female rats it was decreased in comparison with that in the male animals. The LH concentration (per 1 mg of protein) was maximal in the pineal gland extracts of 5-day male and female rats. Gonadectomy of rats led to an approximately double elevation of the LH content in the pineal gland on the 13th postoperative day both in male and female rats. This index was restored to control values three weeks after the operation. From the onset to the termination of diestrus in hamsters the LH content in the pineal gland decreased from 215 to 75 pg/organ, and after diestrus followed by proestrus and estrus it rose to 180 pg/organ (P less than 0.05). A reduction of the LH content to the 10th postoperative day followed hypophysectomy in male and female pubertant rats; the gonadotropin content was restored in two weeks.