Changes in the secretory activity of organs producing noradrenaline upon inhibition of its synthesis in neonatal rat brain

The study is devoted to investigating the humoral interaction of the organs that are major sources of the morphogenetic factor noradrenaline in the general circulation system of rats in the neonatal period of development. The change in the synthesis of noradrenaline in the central and peripheral organs when its synthesis in the brains of neonatal rats is switched off was considered as one of the mechanisms of such interaction. For this purpose, the level of gene expression and the content of enzymes involved in the synthesis of noradrenaline—tyrosine hydroxylase (TH) and dopamine-β-hydroxylase (DBH)—was determined in the brain, adrenal glands, and the organ of Zuckerkandl. The synthesis of noradrenaline after destruction of noradrenergic neurons was switched off by injecting anti-DBH-saporin-antibodies against dopamine-β-hydroxylase conjugated to the cytotoxin saporin into the cerebral ventricles of neonatal rats. The content of TH and DBH mRNA in organs was determined by realtime PCR, and the protein content of enzymes was determined by Western blotting. It is shown that, 48 h after switching off the synthesis of noradrenaline in the brain of 2-day-old animals, a sharp increase in TH and DBH mRNA content in adrenal glands and the organ of Zuckerkandl was observed, although the content of both enzymes was retained at the control level. These data indicate a compensatory enhancement of expression of the genes encoding noradrenaline synthesis enzymes at the transcriptional level as a result of humoral interaction of central and peripheral sources of noradrenaline in the neonatal period of ontogeny.