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α 1 and α 2 Adrenergic receptors in mouse brain astrocytes from primary cultures
Author(s) -
Ebersolt C.,
Perez M.,
Bockaert J.
Publication year - 1981
Publication title -
journal of neuroscience research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.72
H-Index - 160
eISSN - 1097-4547
pISSN - 0360-4012
DOI - 10.1002/jnr.490060509
Subject(s) - prazosin , yohimbine , clonidine , receptor , adrenergic receptor , binding site , endocrinology , cerebral cortex , medicine , chemistry , dissociation constant , alpha 2 adrenergic receptor , divalent , biology , biochemistry , antagonist , organic chemistry
Mouse brain astrocytes from primary cultures were found to contain both α 1 and α 2 adrenergic receptors. 3 H WB 4101 labeled one category of binding site (K D =1.5±0.39 nM, Bmax =64±7.9 fmoles/mg protein) with typical α 1 adrenergic specificity (WB 4101 >prazosin>yohimbine). The density of α 1 adrenergic receptors was 2–3 times higher in mouse cerebral cortex than in glial cells. Like rat brain [U'Pritchard et al, 1979; Rouot et al, 1980], mouse glial cells were found to contain two categories of 3 H clonidine binding sites: high affinity sites, which were identical to the high but not to the low affinity sites found in rat brain, since (1) they displayed the same affinity for 3 H clonidine (K D =1.2±0.13 nM, n=4) and the same typical α 2 adrenergic specificity (yohimbine>WB 4101 > prazosin); (2) the dissociation rate constant for clonidine binding was equal to 0.06 min −1 , a value close to that found previously for the high affinity 3 H clonidine binding sites in rat brain (0.05 min −1 ); and (3) divalent cations augmented and guanyl nucleotides reduced 3 H clonidine binding as in rat brain. Na + decreased 3 H clonidine binding in a complex manner. The number of high affinity sites in glial cells (52 ±9.4 fmoles/mg protein, n=4) was half the number found in mouse cerebral cortex (98 fmoles/mg protein). Low affinity 3 H clonidine binding sites (K D =81±18 nM, Bmax=96±5.8 fmoles/mg protein, n=3) were not fully characterized. In conclusion, glial cells contained the same α adrenergic receptors as those described in brain, but their physiological function is not yet known.