Quantitative analysis of the localization of adrenergic binding sites in chick brain

In the present work [3H]-WB4101, [3H]-DHA, and [3H]-clonidine were used for the study of the localization of alpha 1, alpha 2, and beta adrenergic receptors in the chick brain. The highest concentration of [3H]-WB4101 was observed in the nucleus pretectalis, followed by the nucleus brachium conjunctivum descendens. The superficial layers of stratum griseum fibrosum superficiale, the nucleus mesencephalis lateralis pars dorsalis, and the locus coeruleus showed concentrations of [3H]-WB4101 binding higher than 300 fmoles/mg protein. Concentrations of [3H]-DHA binding higher than 300 fmoles/mg protein were observed in the paleostriatum, the external part of nucleus pretectalis, the nucleus isthmi parvocellularis, the nucleus mesencephalis lateralis pars dorsalis, the dorsal nucleus of oculomotor center, and the molecular layer of cerebellum. Locus coeruleus was the only area of chick brain which showed concentration of [3H]-clonidine binding higher than 300 fmoles/mg protein. With few exceptions, [3H]-clonidine binding was very low and in the telencephalon it was undetectable.