Body growth and substrate partitioning for fat and protein gain in weaned BALB/c mice treated with growth hormone.
Previously we have found that recombinant human growth hormone (rhGH) (GH; 74 ng g body wt.(-1)) administration to weaned BALB/c male mice (fed 12% or 20% protein diet) induced a growth lag and subsequent repletion similar to the catch-up growth process. We studied the partitioning of feed and protein intakes between adipose and protein body stores through the linear relationships among them. The non-linear relationship of protein intake with body fat gain/protein gain (FG/PG) ratio was especially adequate in determining the partitioning of substrates. rhGH induced an increase in feed and protein intake utilization for body weight gain (50%) and fat gain (75-140%) over saline; macronutrient utilization was the greatest in rhGH-treated mice fed 20% protein. However, growth recovery of rhGH mice was anomalous and protein intake was derived primarily for fat gain. Mice fed 12% protein (treated and control) also derived protein intake in preference to fat stores. Treatment and diet had a cumulative effect with the result that rhGH-treated animals fed 12% protein showed the greatest FG/PG ratio (1.6), and therefore, the lowest efficiency to gain protein. Weaning is a critical stage in mice when treating with rhGH, as this could provoke a growth lag. The study showed that a high protein level is required to surpass the rhGH-induced lag, but it is not enough to obtain an enhanced protein deposition. Feeding a 12% protein diet was even worse as mice did not improve on the growth lag and substrates were directed mainly to body fat.
Agis-Torres
A
A
Sección Departamental de Fisiología, Facultad de Farmacia, Universidad Complutense de Madrid, 28040 Madrid, Spain. aagisto@farm.ucm.es
López-Oliva
M E
ME
Unzaga
M T
MT
Muñoz-Martínez
E
E
D000273:Adipose Tissue / Q000187:drug effects*; D000818:Animals; D001823:Body Composition / Q000187:drug effects; D004032:Diet; D004044:Dietary Proteins / Q000494:pharmacology; D019382:Human Growth Hormone / Q000494:pharmacology*; D006801:Humans; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D011506:Proteins / Q000378:metabolism*; D014886:Weaning; D015430:Weight Gain / Q000187:drug effects*
D004044:Dietary Proteins; D011506:Proteins; D019382:Human Growth Hormone