Serotonin 2A receptor function and depression-like behavior in rats model of hypothyroidism

Hypothyroidism causes somatic, psychosocial and affective psychosis, including depression-like behaviors. In this study, (hypothyroidism group; HP group) adult male Sprague Dawley (SD) rats were induced to hypothyroidism after 5 weeks of exposure to 0.05% propylthiouracil (PTU) in potable water, control animals (CON group) were given the same amount of water. The following behavioral experiments were conducted, respectively: open-field test (OFT), forced swimming test (FST), tail suspension test (TST). TT3 and TT4 levels were measured after the behavior tests and the expression levels of 5-HT2A receptor and 5-HT2A receptor proteins were analyzed in the hippocampus and prefrontal cortex. The level of TT3 and TT4 in the HP group rats was much lower than that in the CON group. The hypothyroid rats also showed weight loss, much longer immobility time in tail suspension test and forced swimming test. Besides, 5 weeks of PTU administration was associated with significantly decreased expression levels of 5-HT2A receptor and 5-HT2A receptor proteins compared with control group, which were significantly negatively correlated with immobility time in FST and TST. In conclusion, our results suggest that hypothyroidism induces depressive behaviors through the influence of the serotonin system, and the decreased expression of the 5-HT2A receptor is an important cause of the depressive behaviors in hypothyroidism.

Automated summary

The study revealed that hypothyroidism induces depressive behaviors, with the influence of the serotonin system playing a significant role, and the decreased expression of the 5-HT2A receptor being a crucial factor in the depressive behaviors associated with hypothyroidism.