MATERNAL COORDINATION OF THE DAILY RHYTHM OF MALATE-DEHYDROGENASE ACTIVITY IN TESTES FROM YOUNG-RATS - EFFECT OF MATERNAL SYMPATHETIC DENERVATION OF THE PINEAL-GLAND AND ADMINISTRATION OF MELATONIN

Chronic sympathetic denervation of the pineal gland by bilateral remov al of the superior cervical ganglia (SCG) was performed on female rats 30 days before impregnation. The offspring, maintained in the dark fr om birth, had disruption of the malate dehydrogenase circadian rhythm in the testes at 25 days of age. A daily injection of melatonin (1 mg/ kg s.c. at 10:00 or 18:00 h) to denervated mothers from the 14th day o f pregnancy up to the 10th day postpartum produced one daily phase in the enzyme activity of testes in the offspring. Entrainment of daily e nzyme activity also was obtained when the hormone was administered ora lly to the pups during the postnatal period or when pups were reared b y intact (not denervated) foster mothers. The results indicate the inv olvement of the maternal pineal gland in the maternal transfer of phot operiodic information necessary for the coordination of the circadian system in young rats.