GENETIC-BASED DIFFERENCES IN NEUROTENSIN LEVELS AND RECEPTORS IN BRAINS OF LSXSS MICE

Levels of endogenous neurotensin (NT-IR) in the LS X SS RI strains dif fered by 3.0-, 4.7-, 5.4-, and 6.9-fold in the ventral midbrain (VMB), hypothalamus (HY), nucleus accumbens (NA), and caudate putamen (CP), respectively. Frequency distributions and estimates of the number of g enes indicate that differences in NT-IR are polygenically influenced. The NT-IR levels in NA and CP were significantly correlated, but level s in the VMB did not correlate with those in the NA or CP. Specific bi nding to either low (NT(L))- or high (NT(H))-affinity receptors as mea sured in the absence or presence of levocabastine differed significant ly in brain regions from among LS X SS mouse strains. Results indicate a polygenic influence mediating the differences in receptor densities and suggest differences in genetic regulation of NT(L) and NT(H) rece ptors.