The effect of drugs on accumulation of exogenous norepinephrine in nervous tissue cultured in vitro. IV. The effect of clonidine.

Explants of nervous tissue taken up from the area of locus coeruleus from rats 3-36 days old were cultured in vitro for 15 days, and than accumulation of norepinephrine (3 X 10-8M) was studied with and without preincubation with equimolar concentration of clonidine, using histofluorescence methods. Preincubation with clonidine increased the fluorescence in neural cells, particularly those derived from young animals, in which the pattern of fluorescence appeared to resemble the observed without preincubation only in cells from older animals in addition to fluorescence in the cells, fluorescent granules appeared in neuronal processes and in structures resembling non adrenergic nerve endings. Clonidine completely inhibited norepinephrine uptake by glial cells from very young animals, and inhibited that in the glia in colonies derived from 18-24 days old rats. However, clonidine preincubation restored accumulation of norepinephrine by oligodendroglia from 36 days old rats already lost by this age, but did not affect astrocytes.