Regional and subcellular distribution of gold in brain of gold thioglucose obese mouse.

By employing neutron activation analysis, endogenous content of gold was estimated quantitatively in discrete brain areas and in subcellular fractions of the hypothalamus of gold thioglucose (GTG) induced obese mice. The highest concentration of gold was obtained in the ventromedial hypothalamus (VMH) reaching approximately 100 ng/mg wet tissue. Significantly higher concentrations were observed in other hypothalamic subareas followed by certain limbic areas and the thalamus, while in the cerebral and the cerebellar cortex the gold concentration was very low. Subcellularly, the hypothalamic gold was principally recovered in the supernatant fraction particularly after a hyposmotic shock treatment of the crude mitochondrial fraction. Contrary to GTG, treatment with gold thiomalate (GTM) did not induce obesity in the mouse, although considerable amount of gold was observed in the VMH, a finding suggesting the existence in the VMH of at least a two step mechanisms for inducing GTG obesity. To identify the satiety neuron transmitter, an analysis of certain enzyme activities involved in the synthesis of known transmitters, such as acetylcholine or gamma-aminobutyric acid (GABA), was made in the GTG-obese mice. There were no significant changes in any of the areas functionally related to the VMH.