Reciprocal humoral regulation of endocrine noradrenaline sources in perinatal development of rats

The goal of the present study was to verify our hypothesis of humoral interaction between the norepinephrine secreting organs in the perinatal period of ontogenesis that is aimed at the sustaining of physiologically active concentration of norepinephrine in blood. The objects of the study were the transitory organs, such as brain, organ of Zuckerkandl, and adrenals, the permanent endocrine organ of rats that releases norepinephrine into the bloodstream. To reach this goal, we assessed the adrenal secretory activity (norepinephrine level) and activity of the Zuckerkandl’s organ under the conditions of destructed noradrenergic neurons of brain caused by (1) their selective death induced by introduction of a hybrid molecular complex, which consisted of antibodies against dopamine-β-hydroxylase (DBH) conjugated with saporin cytotoxin (anti-DBH-saporin) into the lateral brain ventricles of neonatal rats; and (2) microsurgical in utero destruction of embryo’s brain (in utero encephalectomy). It was observed that 72 h after either pharmacological or microsurgical norepinephrine synthesis deprivation in the newborn rat’s brain, the level of norepinephrine was increased in adrenals and, conversely, decreased in the Zuckerkandl’s organ. Therefore, the experiments with models of chronical inhibition of norepinephrine synthesis in prenatal and early postnatal rat’s brain revealed changes in the secretory activity of peripheral norepinephrine sources. This, apparently, favors the sustaining of physiologically active norepinephrine level in the bloodstream.