Effects of Stress on Corticosterone Levels, Expression of the c-fos Gene, and Serotonin Metabolism in the Brains of Mice with a Genetic Predisposition to Catalepsy

Abstract

Freezing reactions, or catalepsy, constitute a passive defensive reaction to stress. The involvement of brain serotonin (5-HT) in the regulation of catalepsy has been demonstrated. The main gene controlling the predisposition to catalepsy in CBA mice is located on the 59–70 cM fragment of chromosome 13 in mice. This fragment was transferred from CBA mice to the genome of the non-cataleptic AKR strain to create the congenic strain AKR.CBA-D13Mit76 (D13). The aim of the present work was to compare the effects of acute stress (restraint, 1 h) on the plasma corticosterone level, expression of the c-fos gene (a stress neuromarker), and serotonin catabolism in the brain in mice of the catalepsy-resistant strain AKR and its congenic cataleptic strain D13. Corticosterone levels in stress were significantly lower (p < 0.001) in D13 mice than in AKR animals. Acute stress led to similar increases in c-fos gene expression in the hypothalamus and midbrain of mice of both strains. Stress increased (p < 0.05) serotonin metabolism in the midbrain in mice of congenic strain D13, but not in AKR mice. Thus, the fragment of chromosome 13 containing the main catalepsy gene is involved in regulating hormonal responses and serotonin metabolism in acute stress.