DISTRIBUTION OF ALPHA(2A)-ADRENERGIC RECEPTOR-LIKE IMMUNOREACTIVITY IN THE RAT CENTRAL-NERVOUS-SYSTEM

In this study, we analyzed immunohistochemically the distribution of t he A subtype of alpha(2)-adrenergic receptor (alpha(2A)-AR) in the rat central nervous system using light level immunohistochemistry. By usi ng affinity-purified antisera, we found perikaryal labeling was diffus e and/or punctate; immunoreactive puncta were heterogeneous in size an d number in a region-specific manner. Dense deposits of immunoreaction product were found associated with neuropil also, particularly in the lateral parabrachial nucleus, locus coeruleus, lateral septum, diagon al band, stratum lacunosum-moleculare of CA1, and various nuclei of th e amygdala and extended amygdala. Prominently immunoreactive olfactory structures include the anterior olfactory nucleus and the granular la yer of the olfactory bulb. The cortex was generally light to moderatel y labeled with greater immunoreactivity in the cingulate and insular c ortices. alpha(2A)-AR-like immunoreactivity was intense in the basal f orebrain and continuous from the nucleus accumbens through the substan tia innominata and fundus of the striatum. Most immunoreactivity in th e diencephalon was restricted to the hypothalamus with light to modera te labeling in the thalamus. Generally light immunoreactivity was obse rved in midbrain structures. In the pens and medulla, both perikaryal and neuropil labeling were observed. Together with the accompanying pa per describing the neural distribution of alpha(2c)-AR-like immunoreac tivity, our results provide an extensive immunohistochemical cartograp hy of alpha(2)-ARs in the adult rat central nervous system. (C) 1996 W iley-Liss, Inc.