title: Growth and development of male "little" mice assessed with Parks' theory of feeding and growth.
abstract: This work was designed to characterize the appetite kinetics and growth of male C57BL/6J (lit) mice. Those variables were assessed with Parks' function of ad libitum feeding and growth. Heterozygous mice (lit/+) attained their mature weight at 12-15 weeks of age, peak growth rate (3.5 g/week) at 5 weeks and displayed the normal decay of food conversion efficiency as a function of age. The homozygous genotype has a chronic defect in the synthesis and secretion of growth hormone (GH). Homozygous mice could not be assessed with Park's function. From the 4th to the 15th week of age, body weight increased linearly and exhibited constant food conversion efficiency. Food intake of both genotypes was commensurate with their body weights. Lit/lit mice became progressively obese. At 40 weeks of age, body fat of lit/lit mice was fivefold that of lit/+ and their body weight was similar to their heterozygous controls. The chronic deficiency of growth hormone produced a lower bone mass (compared to heterozygous controls). Bone mass of both genotypes attained maturity at 12-15 weeks with a maximum growth rate at 5 weeks. Body weight and bone mass grow harmoniously in lit/+ but not in lit/lit mice.
authors.affiliation: Laboratorio de Biología Osea, Facultad de Ciencias Médicas, Rosario, Argentina. rpuche@unrctu.edu.ar
authors.forename: Rodolfo C
authors.initials: RC
authors.lastname: Puche
authors.forename: Rosa
authors.initials: R
authors.lastname: Alloatti
authors.forename: Gustavo
authors.initials: G
authors.lastname: Chapo
mesh_terms: D000273:Adipose Tissue / Q000033:anatomy & histology; D000818:Animals; D001066:Appetite / Q000235:genetics* / Q000502:physiology*; D001835:Body Weight; D015519:Bone Density / Q000235:genetics / Q000502:physiology; D004435:Eating; D005838:Genotype; D006128:Growth / Q000235:genetics* / Q000502:physiology*; D013006:Growth Hormone / Q000172:deficiency; D006579:Heterozygote; D006720:Homozygote; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008954:Models, Biological; D010641:Phenotype; D015430:Weight Gain
chemical_list: D013006:Growth Hormone