Weanling ventromedial hypothalamic syndrome. bone geometry and biomechanics.
The effect of growth-retarding, obesifying lesions in the ventromedial hypothalamic nucleus (VMN) on bone geometry and biomechanics was investigated in male weanling rats. The animals received bilateral, symmetrical, electrolytic lesions (VMNL rats) shortly after weanling (age 27 days); sham-operated rats served as controls (SCON). The rats were maintained for 42 postoperative days and then terminated. Body weight, nose-tail length, food intake, carcass water, and lean body mass were all significantly (p < 0.001) reduced in the VMNL group compared to SCON rats. Carcass fat, lipogenic efficiency (carcass fat % laid down/mean food intake) (both p < 0.001) and epididymal fat pad weight (p < 0.01) were significantly increased in VMNL versus SCON. Femur length, anteroposterior diameter (both p < 0.001), and mediolateral femur diameter (p < 0.01) were significantly reduced in VMNL versus SCON rats, but torque and angle of torque were comparable among the groups. VMNL rats femora also showed a significant greater maximum shear stress compared to the control animals. The reduced parameters in the VMNL rats are in good agreement with the previously demonstrated reduced plasma and pituitary growth hormone levels found in this hypothalamus preparation.
State University of New York at Buffalo, Departments of Medicine, 3495 Bailey Ave., Buffalo, NY 14215, USA.
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D000818:Animals; D001696:Biomechanical Phenomena; D001823:Body Composition; D001835:Body Weight; D001842:Bone and Bones / Q000473:pathology*; D006130:Growth Disorders / Q000150:complications / Q000209:etiology / Q000473:pathology*; D007027:Hypothalamic Diseases / Q000150:complications*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013314:Stress, Mechanical; D014697:Ventromedial Hypothalamic Nucleus / Q000473:pathology* / Q000601:surgery