BIOCHEMICAL PARAMETERS OF DOPAMINERGIC AND GABAERGIC NEUROTRANSMISSION IN THE CNS OF ROMAN HIGH-AVOIDANCE AND ROMAN LOW-AVOIDANCE RATS

The dopaminergic (DAergic) and GABAergic pathways in the central nervo us system (CNS) are involved in the control of emotions, in the reacti vity to stressful stimuli, and in the positive and negative reinforcin g properties of psychotropic drugs. In the present review, we summariz e the differences in a range of neurochemical markers of GABA- and DA- mediated neurotransmission in the CNS of Roman high-avoidance (RHA/Ver h) and Roman low-avoidance (RLA/Verh) rats, two psychogenetically sele cted lines that differ in what may be considered to be level of emotio nality. The stimulatory effect of GABA on Cl-36(-) uptake was less pro nounced in the cerebral cortex of RLA/Verh rats compared to RHA/Verh r ats. In addition,the binding affinity of [S-35]TBPS, a selective ligan d of the convulsant site located in the chloride channel of GABA(A) re ceptors, was significantly lower in the hippocampus of RLA/Verh rats t han in their high-avoidance counterparts. On the other hand, the densi ty of D-1 DA receptors labeled with [H-3]SCH 23390 was lower in the nu cleus accumbens of RLA/Verh rats compared to RHA/Verh rats. Brain micr odialysis studies demonstrated that tail-pinch stress and subconvulsan t doses of the anxiogenic compound pentylenetetrazol increased the ext racellular concentrations of DA in the prefrontal cortex of hypoemotiv e RHA/Verh rats but not in their hyperemotive RLA/Verh counterparts. T hese line-dependent differences in GABAergic and DAergic neurotransmis sion may contribute to the distinct emotionality and responsiveness to centrally active drugs of RHA/Verh and RLA/Verh rats.