Contingent and non-contingent effects of low-dose ethanol on GABA neuron activity in the ventral tegmental area.
Ventral tegmental area (VTA) GABA neurons appear to be critical regulators of mesocorticolimbic dopamine (DA) neurotransmission, which has been implicated in alcohol reward. The aim of this study was to evaluate the effects of low-dose "non-contingent" intravenous (IV) ethanol (0.01-0.1 g/kg) on VTA GABA neuron firing rate and synaptic responses, as well as VTA GABA neuron firing rate during low-dose "contingent" IV ethanol self-administration. Intravenous administration of 0.01-0.03 g/kg ethanol significantly increased VTA GABA neuron firing rate and afferent-evoked synaptic responses. In the runway self-administration paradigm, presentation of an olfactory cue (S+; almond extract) or no-cue (S-; no odor) in the Start box was paired with IV administration of low-dose ethanol (0.01 g/kg) or saline in the Target box. Runway excursion times decreased significantly in association during S+, and increased significantly during S- conditions. The firing rate of VTA GABA neurons markedly increased when rats received 0.01 g/kg IV ethanol in the Target box. VTA GABA neuron firing increased in the Start box of the runway in association with S+, but not S-. These findings demonstrate that VTA GABA neurons are activated by low-dose IV ethanol and that their firing rate increases in anticipation of ethanol reward.
Steffensen
Scott C
SC
Brigham Young University, Provo, UT 84602, USA. scott_steffensen@byu.edu
Walton
Christine H
CH
Hansen
David M
DM
Yorgason
Jordan T
JT
Gallegos
Roger A
RA
Criado
Jose R
JR
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D002492:Central Nervous System Depressants / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D003216:Conditioning, Operant / Q000187:drug effects*; D004594:Electrophysiology; D000431:Ethanol / Q000008:administration & dosage / Q000009:adverse effects / Q000494:pharmacology*; D005110:Extracellular Space / Q000187:drug effects / Q000502:physiology; D007275:Injections, Intravenous; D008297:Male; D009474:Neurons / Q000187:drug effects* / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012201:Reward; D012646:Self Administration; D013375:Substance Withdrawal Syndrome / Q000523:psychology; D013569:Synapses / Q000187:drug effects; D017557:Ventral Tegmental Area / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000502:physiology*
D002492:Central Nervous System Depressants; D000431:Ethanol; D005680:gamma-Aminobutyric Acid