?(1)- and ?(2)-adrenergic receptors in rat corpus striatum.

Rat corpus striatum contained ?(2)-adrenergic receptor which were labelled with [(3)H]clonidine (95 +/- 6 fmol/mg protein). The affinity of these receptors (K(d) = 1.3 to 3.6 nM) was similar to that found in cerebral cortex. Five days after kainic lesions, the number of ?(2)-adrenergic receptors had dropped by half, suggesting that their location might be neuronal. One month after lesions, the number of ?(2)-adrenergic receptors had risen to that of the controls and was higher after two months. This increase would suggest a glial localization of the ?(2)-adrenergic receptor. We have previously described the presence of ?(2)-adrenergic receptors in primary astrocyte cultures (Ebersolt et al., 1981). Rat corpus striatum contained less ?(1)-adrenergic receptors than ?(2)-adrenergic receptors. They were labelled with [(3)H]prazosin (28 +/- 1.9 fmol/mg protein) and were only slightly altered 5 days after kainic acid lesions (?20%). In addition to these classical ?(1)-adrenergic receptors, rat corpus striatum also contained [(3)H]WB4101 binding sites having high affinity for WB4101 (2-5 nM) and norepinephrine (1 ?M) but a very low affinity for prazosin (4.4 ?M). The exact nature of these sites remains unknown.