Exposure to TMT odor affects adrenal sympathetic nerve activity and behavioral consequences in rats

The odor of 2,5-dihydro-2,4,5-trimethylthiazoline (TMT), a synthetic compound isolated from fox feces, induces various emotional behavioral and stress responses. Here we examined the effect of TMT on behavioral responses and adrenal sympathetic nerve activity (ASNA) in rats. TMT increased freezing behavior, defensive-burying and defensive-attack, and decreased exploration, grooming and approach behaviors. On the other hand, butyric acid (BA), a pungent but non-predatory odor, increased defensive-burying only. TMT increased ASNA strongly, whereas the effects of BA increased ASNA extremely weakly. Furthermore, pre-treatment with the histaminergic H1-receptor antagonist diphenhydramine eliminated the effects of TMT on ASNA. These findings suggest that TMT odor affects autonomic neurotransmission via histaminergic neurons. Exposure to TMT odor likely regulates the controlling autonomic function and output to a motor system simultaneously, evoking behavioral stress responses.