The glycoprotein gp130 mediates intracellular transduction of signal from receptors of cytokines belonging to the interleukin-6 group. The linkage of the Il6st gene encoding the gp130 protein to heritable predisposition to hypertrophic freezing reaction (catalepsy) has been demonstrated previously in mice. The aim of the present work was to investigate the levels of Il6st mRNA, as well as the distribution of the gp130 protein and the degree of its glycosylation, in five brain regions of mice of the non-cataleptic AKR/J line and the cataleptic lines CBA/LacJ and congenic line AKR.CBA-D13Mit76, which carries the CBA variant of the Il6st gene in the AKR/J genome. These parameters were also studied in mice of the ASC line obtained by backcrossing CBA and AKR mice with the simultaneous selection for the high predisposition to catalepsy. Maximum levels of unglycosylated and glycosylated forms of the gp130 protein were detected in the midbrains of mice from all investigated lines. The highest levels of Il6st mRNA were found in the midbrain, striatum, and hypothalamus of mice of all lines. The level of Il6st mRNA in the striatum of AKR.CBA-D13Mit76 mice was higher than in the striatum of AKR/J mice. Therefore, one can assume that there is a connection between heritable catalepsy and the increased expression of the Il6st gene in the striatum.