Light-Induced Changes in Pineal Hydroxyindole-O-Metthyltransferase: Abolition by Lateral Hypothalamic Lesions

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Science  18 Nov 1966:
Vol. 154, Issue 3751, pp. 898-899
DOI: 10.1126/science.154.3751.898


The activity of hydroxyindole-O-methyltransferase, the melatoninforming enzyme in the pineal gland, is several times greater in rats kept in continuous darkness than in those kept in continuous light. Lesions transecting the medial forebrain bundle in the lateral hypothalamus suppress these differences in enzyme activity and abolish light-induced changes in pineal weight. These findings indicate that the medial forebrain bundle may participate in the control of this enzymatic response to environmental lighting.