Systemic injection with DSP-4 decreases the clonidine hypotension in bicuculline-treated rats

The effect of DSP-4 [N-/2-chloroethyl/-N-ethyl-2-bromobenzylamine] upon blood pressure and of clonidine hypotension before and after bicuculline treatment were studied in rats. Normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were injected with DSP-4 at the dose of 50 mg/kg i.p. twice. Clonidine was given i.p. at the dose of 10 microg/kg in SHR and 20 microg/kg in WKY at the 7th, 9th and 15th day after DSP-4 administration. Bicuculline was injected at the dose of 1mg/kg i.p. The blood pressure and clonidine hypotension appeared unaffected by DSP-4 pretreatment in WKY and SHR rats. In both rat strains the bicuculline reduced clonidine hypotension and the phenomenon was augmented after DSP-4 lesioning. The data suggest that the alterations in GABAergic and other neurotransmitter system function evoke increasing effect of bicuculline.