Fc. Barone et al., GABA INHIBITION OF LATERAL HYPOTHALAMIC NEURONS - ROLE OF RETICULAR THALAMIC AFFERENTS, Brain research bulletin, 33(6), 1994, pp. 699-708
GABA and reticular thalamic (RT) stimulation induced inhibition of lat
eral hypothalamic (LH) neuronal activity was studied to determine if R
T inhibitory input to the LH is mediated by stimulation of GABA recept
ors. Seven barrel electrodes were utilized to record simultaneously fr
om the LH during microiontophoretic application of GABA, glycine, bicu
culline, picrotoxin, and electrical stimulation of the RT. GABA produc
ed an ejection current-related decrease in LH neuronal activity that w
as antagonized, in a dose-related manner, by the simultaneous administ
ration of picrotoxin or bicuculline. LH neurons were much less sensiti
ve to glycine inhibition which also was relatively insensitive to the
GABA receptor antagonists. RT electrical stimulation provided a short
latency inhibitory input to LH neurons that was mimicked by the microi
ontophoretic administration of GABA. In addition, the microiontophoret
ic application of picrotoxin or bicuculline blocked the RT stimulation
induced inhibition of LH neuronal activity. These data indicate that
the inhibitory effects of both GABA and RT synaptic inputs onto LH neu
rons are mediated by stimulation of GABA, receptors and substantiates
the involvement of GABA as the inhibitory transmitter of thalamic to h
ypothalamic projections.