Possible mechanism of interaction of GABAergic-adenosinergic systems in the regulation of theophylline-induced locomotor activity under its nontolerant and tolerant conditions.

The measurement of locomotor activity (LA) of theophylline (Th) nontolerant (10 mg/kg, p.o.) rats using agonist and antagonist of different neurotransmitters either in single or in their different combinations suggest that an inhibition of central GABAergic activity as well as adenosinergic and serotonergic activities through the stimulation of dopaminergic activity followed by an inhibition of cholinergic system may stimulate LA in Th nontolerant condition. Further, it is suggested that the development of tolerance to Th restored the LA to control value may be due to an activation of adenosinergic system which possibly withdrew the inhibition occurred in central cholinergic, GABAergic and serotonergic activities followed by the modulation of dopaminergic system.