Non-production of hypothalamic obesity in the rat by lesions rostral or dorsal to the ventro-medial hypothalamic nuclei
✍ Scribed by A. W. Hetherington
- Publisher
- John Wiley and Sons
- Year
- 1944
- Tongue
- English
- Weight
- 881 KB
- Volume
- 80
- Category
- Article
- ISSN
- 0021-9967
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✦ Synopsis
SIX FIGURES
Thc production of hypothalamic obesity in the rat is an easy matter, requiring only that certain definite regions on both sides of the hypothalamus be destroyed. Work in this laboratory has been directed toward the identification of the precise structures, either nuclei or fiber groups, destruction of which is followed by adiposity. The view was finally advanced (Hetherington and Ranson, '42) that obesity is caused by "lesions which occupy the medial hypothalamus, particularly the region of the ventromedial hypothalamic nucleus, or are placed in the caudal hypothalamus in a position to interrupt a large number of descending fibers from the hypothalamic cell group& " The mammillary nuclei, and probably also the premammillary nuclei, the mamillothalamic tract, the fornix, and the periventricular and suprachiasmatic nuclei were considered to be unconcerned in the syndrome.
The question which arose next was to what extent the hypothalamic outflow of fibers controlling fat metabolism was contributed to by fibers originating in cell groups lying more rostrally than those previously destroyed. Admittedly, large lesions in the central and caudal hypothalamus probably interrupt many fibers travelling caudally from regions lying rostral to the ventromedial hypothalamic nuclei (viz., the anterior hypothalamic and preoptic areas and the cell groups of the basal olfactory forebrain). The influence of such hypothalamic lesions in producing obesity might not depend entirely -or even at all -upon their destruction of local cell bodies, but rather upon their severance of the connections between more rostral centers and the lower brain-stem. Such an assumption is unquestionably true in the case of the most caudal obesity-producing hypothalamic lesions. Ob-