GABA-INDUCED LOCOMOTOR-ACTIVITY IN THE RAT, AFTER BILATERAL INJECTION INTO THE VENTRAL TEGMENTAL AREA

Bilateral injections of γ-aminobutyric acid (GABA: 10-100 μg) into the ventral tegmental area (VTA) of the rat, induced locomotor hyperactivity. This hyperactivity was antagonized by pretreatment with picrotoxin (4 mg/kg ip). Dopamine concentrations were unaltered in either the mesolimbic (nucleus accumbens plus olfactory tubercle, NAOT) or striatal regions. Concentrations of HVA however, were elevated above control levels in the NAOT 2 hr after GABA injections, following probenecid (200 mg/kg, ip) pretreatment. In contrast the GABA analogue, β-(chiorophenyl)-GABA, induced sedation after its bilateral injection into the VTA. Dopamine concentrations were increased in the NAOT but not in the striatum, 2 hr after such injections. Concentrations of HVA in the NAOT were increased above control levels following probenicid pretreatment. Picrotoxin did not antagonise the baclofen-induced sedation. These observations are discussed in the light of a possible role of GABA in the VTA. © 1979.