Gene c-Fos expression in brain of rats resistant and predisposed to emotional stress after intraperitoneal injection of the ACTH(4-10)analog--semax

The effect of the ACTH(4-10) analog Semax on immediate early gene c-Fos expression was studied in Wistar rats with high and low resistance to emotional stress under the usual conditions and during psychoemotional loading. Fos-immunoreactive cells in the were counted automatically with the help of a computer. It was shown that under the usual conditions the intraperitoneal Semax injection induced immediate early gene c-Fos expression in the lateral septal region in rats predisposed to emotional stress and in the paraventricular hypothalamus in rats of both groups. Preliminary Semax injection decreased the stress-induced c-Fos expression in the paraventricular hypothalamus and medial septum in rats predisposed to emotional stress and tended to reduce the number of stress-induced c-Fos-immunopositive cells in the lateral septum and basolateral amygdala in both groups of animals. The obtained data suggest that Semax differently affects the immediate early c-Fos gene expression in the brain of rats resistant and predisposed to emotional stress and this effect reflects the antistressor properties of the regulatory peptide.