Hereditary catalepsy in mice is associated with the brain dysmorphology and altered stress response

Catalepsy is a passive defensive strategy in response to threatening stimuli. In exaggerated forms it is associated with brain dysfunctions. The study was aimed to examine (1) possible association of the hereditary catalepsy with neuroanatomical characteristics and (2) sensitivity of the catalepsy expression, HPA and brain serotonin (5-HT) systems to restraint stress (for one hour) in mice of catalepsy-prone (CBA/Lac, ASC (Antidepressant Sensitive Catalepsy), congenic AKR.CBA-D13M76) and catalepsy-resistant (AKR/J) strains. Magnetic resonance imaging showed that the catalepsy-prone mice were characterized by the smaller size of the pituitary gland and the larger size of the thalamus. In ASC mice, diencephalon region (including hypothalamus) and striatum were significantly reduced in size. Restraint stress provoked catalepsy in AKR mice and enhanced it in the catalepsy-prone mice. Stress-induced corticosterone elevation was diminished, while 5-HT metabolism (5-HIAA level or 5-HIAA/5-HT ratio) in the midbrain was significantly augmented by stress in the catalepsy-prone mice. The multivariate factor analysis revealed interactions between the basal levels and the stress-induced alterations of 5-HT metabolism in the hippocampus and midbrain suggesting the interaction between multiple alterations in 5-HT neurotransmission in several brain structures in the regulation of hereditary catalepsy. The study indicated an association between the hereditary catalepsy, neuroanatomical characteristics, and neurochemical responses to emotional stress. The catalepsy-prone genotypes seem to be more susceptible to stress that suggests them as the adequate models to study the genetic predisposition to stress-based neuropathology. The data support the association of hereditary catalepsy with the inherited brain dysfunction of a neurodegenerative nature.