EFFECT OF PINEAL PREPARATION EPITHALAMIN ON NIGHT SERUM LEVEL OF MELATONIN, PROLACTIN AND LUTEINIZING-HORMONE IN MALE-RATS

Three-month-old male LIO rats were exposed to a sing le subcutaneous d ose 10 mg/kg of pineal peptide Preparation epithalamin at 09:00; 18:00 or 23:00 hours and were sacrificied at 24:00 hours. Control rats were injected with 0. 2 mt of normal saline at 09:00 hours or 23:00 hours and were sacrificied at 10:00 or 24:00 hours, respevtively. The night level of melatonin, Prolactin and luteinizing hormone (LH) was increas ed in control males in comparison with the morning level of the hormon es. Morning exposure to epithalamin inhibits, while day-time or night injections failed to Influence the night level of melatonin in the rat serum. The night serum level of prolactin and LH was inhibited by inj ections of epithalamin at any time of day.