gamma-Aminobutyric acid and mu-opioid receptor localization and adaptation in the basal forebrain

In conclusion, GABAA receptors containing the alpha 1 subunit are localized on postsynaptic neurons in the ventral pallidum, mainly in the dorsolateral compartment and on presynaptic terminals in the nucleus accumbens. mu-opioid receptors are localized on postsynaptic neurons in both the nucleus accumbens and ventral pallidum, and therefore may be regulating presynaptic release of enkephalin from the accumbens-pallidal projection. Discrete lesions in the dorsomedial core of the nucleus accumbens will upregulate GABAA receptors in the dorsolateral compartment of the nucleus accumbens in a fashion similar to the upregulation of GABAA receptors in the globus pallidus after striatal lesions. However, larger lesions of the lateral core projection to the dorsolateral compartment of the ventral pallidum do not upregulate the GABAA receptors, suggesting that the mechanisms for upregulation of GABAA receptors are specific to the dorsomedial core or a smaller lesion. The uniqueness of the compartments within the nucleus accumbens and the ventral pallidum are supported by these receptor and mRNA analyses.