Somatostatin, cholecystokinin and neuropeptide Y mRNAs in normal and weaver mouse brain

The distribution of mRNAs encoding for somatostatin, cholecystokinin and neuropeptide Y was determined by in situ hybridization histochemistry in the weaver (wv/wv) mouse, a model of dopamine deficiency as well as in normal (+/+) controls. Weaver mutants did not show any appreciable departure from the normal pattern of expression for mRNA encoding for neuropeptide Y. In contrast, an 82% increase in mRNA encoding for somatostatin was observed in the reticular thalamic nucleus, whereas increases in the order of 20–87% were observed in different hypothalamic nuclei of the weaver brain. In addition, a 47–103% increase of the hybridization signal encoding for choleocystokinin was observed in the cerebral cortex, hippocampus and thalamus of the weaver brain. It can be assumed that the elevated and region-specific somatostatin and choleocystokinin levels observed in the weaver brain may be due to a secondary or compensatory response under conditions of altered neurotransmitter levels.