Method for quantitative operant response measurement during inhalation exposure.

A method for pharmacologic and toxicologic investigation of operant responses during inhalation exposure has been developed. The method was tested with rats. Toluene was utilized as a reference chemical. Toluene has been reported to cause significant increases in response rates of animals responding under operant schedules. A fixed interval schedule (F1-120 sec) was used. A significant increase in response rate was observed. Thus, the results indicated that the method was reliable and allowed operant schedule data to be obtained. The significance of this method lies in its versatility to allow an integrative study of operant response, inhalation kinetics, and pharmacologic action. Potential practical applications of the method include studies of the actions of drugs and chemicals administered via inhalation exposure.

Effects of toluene inhalation on brain biogenic amines in the rat.

The effects of toluene exposure on the biogenic amine concentrations in the central nervous system were investigated in the rat. Toluene was administered via inhalation to groups of rats at concentrations of 0, l00, 300, or 1000 ppm. After an 8-h continuous exposure, animals were sacrificed and whole brain concentrations of dopamine (DA), norepinephrine (NE), and 5-hydroxytryptamine (5-HT) were determined. The data indicated a significant increase in whole brain concentrations of DA following the 100-ppm exposure. A regional analysis of DA, NE, and 5-HT concentrations in rats exposed to 1000 ppm of toluene for 8-h indicated a significant increase in DA concentration in the striatum. A significant increase in NE concentrations was detected in the medulla and midbrain while 5-HT concentrations were significantly increase in the cerebellum, medulla, and striatum. The results indicate that toluene action results in elevated concentrations of behaviorally significant neuro-transmitters.