What are the phenotypes of VTA neurons responsive to cocaine?

Wednesday, October 26, 2011 — Poster Session IV
2:00 p.m. – 4:00 p.m.	Natcher Conference Center	NIDA	NEURO/BEHAV/SENSYS-20

* FARE Award Winner

Authors

• C Mejias-Aponte
• M Morales
• E Kiyatkin
• J Pieper
• R Wise

Abstract

Given intravenously cocaine can either inhibit or excite VTA neurons. However, our knowledge of what types of VTA neurons are responsive to cocaine is based upon indirect electrophysiological evidence. We set the task of phenotyping VTA neurons responsive to intravenous cocaine administration. We recorded VTA neurons in urethane-anesthetized rats. A glass electrode filled with neuronbiotin was used to juxtacellularly label neurons after we recorded changes in discharge rate resulting from intravenous cocaine injections. We labeled 33 VTA neurons: 11 DA neurons (immupositive for tyrosine hydroxylase) and 22 non-DA (immunonegative for tyrosine hydroxylase). We found no significances in action potential duration or discharge rate between DA and non-DA neurons. Of the DA neurons, 7 (63%) were inhibited while 4 (37%) were excited. Of the non-DA neurons, 8 (37%) were inhibited, 6 (27%) were excited, 2 (9%) were excited followed by inhibition, and 6 (27%) were non-responsive. This work provides the first evidence of the effects of intravenous cocaine on histochemically identified DA neurons; it is also the first evidence of the effects of intravenous cocaine on identified non-DA neurons in this region.

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