A pilot study of rat brain regional distribution of calcitonin, katacalcin and calcitonin gene-related peptide before and after antipsychotic treatment

In contrast to extensive determinations of calcitonin gene-related peptide (CGRP) in neural tissues, calcitonin and its carboxyl-terminal flanking peptide katacalcin (in human PDN-21) have not been systematically measured by radioimmunoassay (RIA) in discrete brain structures. Using microwave irradiation (MW), a procedure that increases the recovery of neuropeptides, we investigated by radioimmunoassay (RIA) the rat brain regional distribution of CGRP like- immunoreactivity (-LI), calcitonin-LI, and katacalcin-LI. Calcitonin-LI and katacalcin-LI were found in low concentrations in frontal cortex, occipital cortex, striatum and hippocampus. Moreover, a 4-week treatment with antipsychotic drugs altered the concentrations of the calcitonin-gene family peptides in the frontal cortex, occipital cortex, and hippocampus; the magnitude of these changes, however, was only moderate. Lastly, calcitonin-LI and katacalcin-LI baseline concentrations as well as after antipsychotic treatment were highly correlated in the frontal cortex, striatum, and hippocampus. The possible regulatory role of calcitonin gene family peptides in the central nervous system (CNS) needs to be further explored.