BMAL1—Potential Player of Aberrant Stress Response in Q31L Mice Model of Affective Disorders: Pilot Results

Dysregulation in the stress-response system as a result of genetical mutation can provoke the manifestation of affective disorders under stress conditions. Mutations in the human <i>DISC1</i> gene is one of the main risk factors of affective disorders. It was known that DISC1 regulates a large number of proteins including BMAL1, which is involved in the regulation of glucocorticoid synthesis in the adrenal glands and the sensitivity of glucocorticoid receptor target genes. Male mice with a point mutation Q31L in the <i>Disc1</i> gene were exposed to chronic unpredictable stress (CUS), after which the behavioral and physiological stress response assessed. To assess whether there were any changes in BMAL1 in key brain regions involved in the stress response, immunohistochemistry was applied. It was shown that the Q31L mice had an aberrant behavioral response, especially to the 2 weeks of CUS, which was expressed in unchanged motor activity, increased time of social interaction, and alterations in anxiety and fear-related behavior. Q31L males did not show an increase in blood corticosterone levels after CUS and a decrease in body weight. Immunohistochemical analysis in intact Q31L mice revealed a decrease in BMAL1 immunofluorescence in the CA1 hippocampal area and lateral habenula. Thus, the Q31L mutation of the <i>Disc1</i> gene disrupts behavioral and physiological stress response and the BMAL1 dysregulation may underlie it, so this protein can act as a molecular target for the treatment of affective disorders.