CATECHOLAMINE LEVELS IN DISCRETE BRAIN NUCLEI OF 7 MONTH OLD GENETICALLY-OBESE RATS

Catecholamine levels were measured in microdissected nuclear groups of seven month old, obese and lean, male and female Zucker rats. By analysis of variance, obese rats showed significantly reduced levels of norepinephrine and epinephrine in the paraventricular nucleus and of epinephrine and dopamine in the dorsomedial hypothalamic nucleus. Norepinephrine levels were increased in the median forebrain bundle and caudate nucleus. When compared by sex and genotype (t-test), the female obese rats had significant decreases compared to the leans of norepinephrine and epinephrine levels in the paraventricular and dorsomedial hypothalamic nuclei, while norepinephrine was increased in the median forebrain bundle and caudate nucleus. Dopamine was decreased in the dorsomedial and increased in the C2 nuclei. Male obese Zucker rats showed changes only in the dorsomedial and C2 nuclei where dopamine levels were decreased. In general, female obese and lean rats tended to have lower levels of catecholamines in various brain areas than males of the same genotype. Comparisons of these data to previous studies in younger Zucker rats [9,10] suggested that changes also occurred in various nuclei with aging. It is postulated that catecholamine deficits in certain hypothalamic nuclei of the Zucker obese rat may be a contributing factor to the development and/or maintenance of obesity, possibly in association with abnormalities in thermal regulation. © 1979.