Cyclic nucleotides in the rat caudate-putamen complex: Histochemical characterization and effects of deafferentation and kainic acid infusion

Abstract

Guanosine 3′,5′-cyclic monophosphate (cyclic guanosine monophosphate) and adenosine 3′,5′-cyclic monophosphate (cyclic adenosine monophosphate) were characterized immunohistochemically in the striatum of the rat. Cyclic guanosine monophosphate was associated primarily with fibrillar elements, some of which derived from cell bodies having maximum soma dimensions of 6–10 μm. Cyclic adenosine monophosphate was found primarily in relationship to oval or triangular somata 12–20 μm in maximum extent. Radio-frequency or suction ablations in brain regions—the ventral diencephalon, cortex and thalamus—providing or containing afferents to the caudate-putamen complex produced no effect on histochemical staining patterns or biochemically assessed levels of the two cyclic nucleotides. Loss of immunofluorescence to the two cyclic nucleotides was observed microscopically, however, following intrastriatal infusion of kainic acid; cyclic nucleotides in the non-injected striatum were unchanged. The latter histochemical results could not be corroborated biochemically. Radioimmunoassays showed no net effect of kainic acid on levels of the two cyclic nucleotides in the infused caudateputamen nucleus, whereas levels of these two chemical compounds were increased to 170–219% in the contralateral striatum. It was concluded that, as assessed histochemically, (1) cyclic guanosine monophosphate is primarily associated with glial cells and/or ‘glial-like’ neurons whereas cyclic adenosine monophosphate is found in relationship to neurons and (2) the striatal tissue elements containing these two cyclic nucleotides are organized primarily within the caudate-putamen complex. In addition, (3) immunohistochemical procedures for cyclic nucleotides may assay only tightly bound stores of cyclic nucleotides, whereas biochemical methods may measure both labile and stable pools. This last consideration permits reconciliation of differing results obtained with histochemical and biochemical techniques following intrastriatal infusion of kainic acid.