Baclofen-impairment of memory retention in rats: possible interaction with adrenoceptor mechanism(s)

This study concerned the influence of adrenoceptor agonists and antagonists on baclofen-induced impairment of memory retention. Intracerebroventricular injection of baclofen (0.25--2 microg/rat) reduced memory retention in rats. The combination of different doses of baclofen with a low dose of clonidine (0.5 microg/rat) elicited a greater decrease in memory retention. Yohimbine (1 microg/rat) potentiated the response to a low dose, but decreased the response to higher doses of baclofen. Single administration of clonidine (0.5--2 microg/rat) but not yohimbine (1--4 microg/rat) itself decreased memory retention. The combination of clonidine with yohimbine did not show any interaction. The low dose of phenylephrine (0.5 microg/rat) or prazosin (0.5 microg/rat) also potentiated the inhibition of memory retention by baclofen. Phenylephrine (0.5--3 microg/rat) increased, while prazosin (0.5--2 microg/rat) decreased memory retention. The combination of the two drugs showed an interaction. It may be concluded that an adrenoceptor mechanism may interact with the memory retention impairment induced by baclofen.