[The ontogenetic correlations of noradrenaline level and adrenergic receptor density in the rat brain]

We studied the level of noradrenaline and the density of alpha 2- and beta-adrenoreceptors in the brain stem and cerebral cortex of 12-day- and 21-day-old rat fetuses, as well as of rats at the ages of 1, 2, 5, 7, 9, 16, 21, 35, and 70 days. We found a positive correlation between the level of noradrenaline in the brain stem and the density of beta-receptors in the cerebral cortex, and between the amount of alpha 2- and beta receptors in the cerebral cortex, as well as between the values of each of these indices of the neurochemical system and body weight. Significant negative correlations (r = -0.72 and r = -0.88, respectively) were found between the amount of alpha 2-adreno-receptors in the brain stem and the content of noradrenaline in this brain region, as well as in the cerebral cortex. Explanations of these positive and negative correlations between the level of noradrenaline and the amount of adrenergic receptors in the rat brain during ontogenesis are discussed.

[Regulation of expression of adrenergic receptors by steroid hormones]

Steroid hormones regulate density of adrenergic receptors in peripheral tissues and in the brain. The hormones affect transcription of the adrenergic receptors genes, the receptor protein synthesis and modifications. Steroid-induced changes in adrenergic receptors densities may be an important link for the effects of steroid hormones on hormone-dependent functions and behaviour.

[Sexual behavior and alpha-2 adrenoreceptors in the neocortex of male rats after castration and testosterone administration]

Castration of male rats inhibited their sexual behaviour and increased the density of the alpha-2 adrenergic receptors in the brain cortex. Treatment of castrated or intact males with testosterone activated their sexual behaviour and decreased the receptor density in the brain cortex. The obtained evidence testify to the involvement of the brain alpha-2 adrenergic receptors in the effect of testosterone on male sexual behaviour.