EFFECT OF RESERPINE ON 3-METHOXY-4-HYDROXYPHENYLETHYLENEGLYCOL AND 3,4-DIHYDROXYPHENYLACETIC ACID IN THE HIPPOCAMPUS OF DEPRESSION-MODEL RATS - AN IN-VIVO MICRODIALYSIS STUDY

Using in vivo microdialysis, we examined the effect of intraperitoneal injection of reserpine (2 mg/kg) on hippocampal 3-methoxy-4-hydroxyph enylethyleneglycol (MHPG) and 3,4-dihydroxy-phenylacetic acid (DOPAC). two major metabolites of catecholamine. Responses wen examined serial ly for 12 h in the hippocampus of walking-stress-induced depression-mo del rats, recovery rats and control rats. Control rats showed a rapid rise followed by a gradual fall of free and total MHPG and a delayed i ncrease of DOPAC in response to reserpine. Depression-model rats showe d a significantly blunted biphasic response of free and total MHPG as well as blunted monophasic response of DOPAC compared with control rat s. Recovery rats also exhibited a blunted fall response of MHPG. Our f indings suggest that the vesicle membrane in the central noradrenaline (NA) neurons could be hyposensitive to reserpine in the depression-mo del rats. (C) 1998 Elsevier Science B.V.