Comparative study of the effects of toluene, benzene, 1,1,1-trichloroethane, diethyl ether, and flurothyl on anxiety and nociception in mice.

The main purpose of this study was to compare the effects of solvents from different chemical classes on anxiety and nociception. Independent groups of mice were exposed to air (control group), toluene (1000-4000 ppm), benzene (1000-4000 ppm), 1,1,1-trichloroethane (TCE, 2000-12000 ppm), diethyl ether (10,000-30,000) or flurothyl (200-600 ppm). After a 30-min exposure, animals were tested either in the anxiety paradigm conditioned defensive burying (CDB) test or in the hot plate test. All solvents but flurothyl produced anxiolytic-like actions being the order of potency toluene > benzene > TCE > diethyl ether. When tested in the hot plate paradigm, toluene and TCE increased nociception, benzene and diethyl ether had no effects, and flurothyl decreased nociception Additional groups of mice were conditioned to recognize the aversive stimulus (electrified prod) prior to toluene exposure and then tested in the CDB test. In unconditioned animals, toluene increased the number of shocks that mice received; however, when mice had previous experience in the CDB test, toluene lacked this effect. Taken together, these results show that inhalants have different effects with different potencies both in the CDB and in the hot plate tests. Additionally, data suggest that acute administration of toluene could impair learning.