Effect of melatonin-free pineal extract on cholesterol in basal and HCG treated rats.

The effect of a melatonin-free pineal extract on total, free and esterified testicular and serum cholesterol in the rat under basal conditions and after stimulation with exogenous HCG was followed up. Administration of a 2 ml daily dose from this extract to the rat under basal conditions along 3, 12 and 30 days reduced the esterified fraction of testicular cholesterol, more markedly in the 12-day experiment. The total free and esterified serum cholesterol also diminished significantly in the 3 and 12-day experiments. Under HCG stimulation the pineal extract inhibited the lowering effect of HCG on the esterified fraction in the testis and on the free and esterified fraction at serum level. Under both these experimental conditions, the pineal extract affected the esterified cholesterol at testicular level, a fraction used in androgen hormones production, and the free and esterified serum cholesterol. The auhors comment on the inhibiting role of the pineal extract exerted on testicular synthesis of cholesterol and testosterone under basal conditions as well as the regulating role of the pineal gland under conditions of exogenous HCG stimulation.