[Effect of constant illumination on the response to castration in rats].

The effects of constant light from birth on compensatory ovarian or testicular hypertrophy and gonadotropins levels after gonadectomy have been studied. Ovarian hypertrophy was not affected by constant light either in young or adult rats. The degree of testicular hypertrophy increased in young males submitted to constant light without changes in FSH levels after hemicastration.

Long-term social isolation in the rat induces opposite changes in binding to alpha 1- and alpha 2-adrenoceptors in the brain and vas deferens.

Rats isolated at the time of calcification of the incisors show, after 14-18 months of social deprivation, an increased number of alpha 1-adrenoceptors labeled with [3H]WB 4101, both in the striatum and in the vas deferens, as well as a decreased number of alpha 2-adrenoceptors labeled with [3H]-clonidine in the vas deferens. Social isolation does not, however, modify the density of [3H]clonidine binding sites in the cerebral cortex. The functional state of alpha-adrenoreceptors in the vas deferens from isolated rats appears to correlate with the binding studies since the isolated tissue is hypersensitive to the contractile effect of exogenous noradrenaline and subsensitive to the inhibitory effect of clonidine on the electrically stimulated preparation.