[Monoaminergic structures of the hypothalamus in chronic stress]

Falk's histochemical fluorescent method was used to study monoamine (MA)-containing structures in isolated hypothalamus nuclei and in the neurohemal region of the medial eminence (ME) in 40 male rats under the conditions of a long-term stress (6 months) which was caused by a repeated weak electrodermal stimulation. A statistically significant decrease in the intensity of MA fluorescence in the early period of the experiment, particularly significant in the fibers of the paraventricular nucleus and in the ME, was replaced by an increase in the intensity of MA fluorescence in the fibers and perikaryons in the arcuate paraventricular nuclei and in the ME on the 100th day. On the 180th day of the experiment MA fluorescence in the hypothalamus structures of the experimental and control rats did not differ significantly. Thus MA in the hypothalamus nuclei and ME were involved in adaptation processes of the body to chronic stress action. Changes of the MA content were particularly marked in the paraventricular nucleus, associated with cortical RH and vasopressin production as well as in the arcuate nucleus and in the ME associated with the entry of these hormones in the hypophysial portal vessels to regulate ACTH secretion.