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  • Title: Diurnal rhythms in pineal N-acetyltransferase and hippocampal norepinephrine: effects of water deprivation, blinding and hypothalamic lesions.
    Author: Moore RY, Traynor ME.
    Journal: Neuroendocrinology; 1976; 20(3):250-9. PubMed ID: 986580.
    Abstract:
    The pineal gland in the rat exhibits a diurnal rhythm in activity of the enzyme serotonin N-acetyltransferase (N-AT) with peak values during the dark period of a diurnal lighting schedule approximately 100-fold those during the light period. After blinding the rhythm becomes free-running. It is abolished by partial hypothalamic deafferentation with a knife cut made caudal to the optic chiasm. Water deprivation for 23 h daily has no effect on the pineal rhythm in either intact, blinded or deafferented animals. In contrast to this, there is a diurnal rhythm in hippocampal formation in norepinephrine content which can be entrained by a water deprivation schedule in both intact and blinded animals. These observations indicate that in the same animals 1 diurnal rhythm may remain entrained to the light-dark cycle while another rhythm is entrained to a secondary synchronizer, the water deprivation schedule.
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