The role of central noradrenergic mechanism on head-twitch response induced by estazolam

The effect of central noradrenergic neuron system on head-twitch response: (HTR) induced by estazolam (0.03mmol/kg,i.p.), benzodiazepine derivative we re studied in mice. Following pretreatment with reserpine (1mg/kg,i.p.), 6- hydroxydopamine (6-OHDA:40 ug/mouse.i.c.v.). alpha -methyl-p-tyrosine (alph a -MPT:125mg/kg,i.p) and diethyldithiocarbamate (DDC:100mg/kg,i.p.). the to tal number of head-twitches induced by estazolam (0.03mmol/kg,i.p.) was inc reased. However, norepinephrine (1 and 2 mug:mouse; i.c.v.) and Phenylephri ne (0.5 and 1mg/kg,i.p.;.) significantly decreased estazolam-induced HTR, b ut not haloperidol. These: results suggest that the central catecholaminerg ic system exerts an inhibitory effect on estazolam-induced HTR.