Effect of xylene inhalation on fixed-ratio responding in rats.
The effect of xylene inhalation was studied on operant behavior under a fixed-ratio (FR24) schedule in rats. Experiments were performed while rats were being exposed to xylene vapor in an inhalational (flow-through) behavioral chamber. Rats were exposed successively to three graded concentrations (113, 216 and 430 ppm) of xylene vapor each for 2 hr in range-finding studies during 6 1/4-hr sessions. The reinforcement rate which is correlated with FR responding was shown to be decreased at hr 1, hr 3 and hr 5. However at hr 2, hr 4 and hr 6 the reinforcement rate in rats increased approaching the control levels, thereby indicating development of tolerance. When rats were exposed to one of the three graded concentrations of xylene for 2 hr on separate days, they also showed a decrease in the reinforcement rate at hr 1; development of acute tolerance was also noted in this schedule. Exposure to the lowest (98.5 ppm) level of xylene used during 5-hr sessions caused no significant decrease in the reinforcement rate. This study thus attempts to identify a minimum effective concentration of xylene and indicates the development of acute tolerance to behavioral effect of xylene.
Ghosh
T K
TK
Department of Pharmacology, Howard University College of Medicine, Washington, DC 20059.
Copeland
R L
RL
Parui
R N
RN
Mookherjee
S
S
Pradhan
S N
SN
D000280:Administration, Inhalation; D000818:Animals; D003216:Conditioning, Operant / Q000187:drug effects*; D004361:Drug Tolerance; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D013997:Time Factors; D014992:Xylenes / Q000494:pharmacology*
D014992:Xylenes