The lateral hypothalamic syndrome in the weanling rat: bone geometry and biomechanics.
Male weanling Sprague-Dawley rats received bilateral electrolytic lesions in the lateral hypothalamic area (LHAL). One group of sham-operated controls was fed ad lib (CON-ADLIB), another was pair fed to the LHAL group (CON-PF). The experiment was terminated 1 month after surgery. At that time, LHAL rats were 49% and CON-PF rats were 41% lighter than CON-ADLIB. Carcass protein in LHAL rats was significantly reduced in LHAL: versus CON-ADLIB. Linear growth was significantly reduced by 18% in LHAL versus CON-ADLIB, as well as LHAL: versus CON-PF by 6%. Mean caloric intake was significantly reduced by 48% in LHAL versus CON-ADLIB, as was caloric efficiency (body weight gained per calories eaten) by 36%, as well as, in CON-PF versus CON-ADLIB by 20%. LHAL rats showed a significantly shorter (10%), narrower (15%) and thinner (25 %) cortex at midshaft of the femur. Resistance to torsional loads was reduced by 25% in both LHAL and CON-PF, but this did not reach statistical significance, in comparison to CON-ADLIB. There was no statistical significance among the groups in stiffness and maximal angular displacement. We conclude that the reduced bone geometrical and biomechanical properties in both LHAL rats and CON-PF versus CON-ADLIB are similar because both former groups of rats were greatly subcaloric. Thus, the changes here observed are not due to a specific neuroendocrine/autonomic lesion effect but may be attributable to the reduced food intake, i.e., nutritional factors.
Bernardis
L L
LL
State University of New York at Buffalo, Department of Orthopaedic Surgery, USA.
Medige
J
J
Gillespie
R
R
Wu
H
H
Zivt
I
I
D000818:Animals; D001696:Biomechanical Phenomena; D001823:Body Composition / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D001846:Bone Development / Q000502:physiology*; D001842:Bone and Bones / Q000033:anatomy & histology*; D004435:Eating / Q000502:physiology; D002149:Energy Intake; D006130:Growth Disorders / Q000503:physiopathology*; D007026:Hypothalamic Area, Lateral / Q000033:anatomy & histology / Q000502:physiology*; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley