The regulation of GH-dependent hormones and enzymes after feed restrictionin dwarf and control chickens

The principal objective of this study was to examine the GH-dependency of I GF-I and IGF-II changes in the chicken. To this end, the regulation of GH-d ependent hormones and enzymes were studied in undernourished normal and dwa rf chickens. The dwarf chickens examined exhibit a Laron-type dwarfism and have been shown to be GH receptor deficient. Thus, they provide an interest ing model to determine the GH-dependency of IGF-I and IGF-II changes. Short (1 day) and long-term (7 days) feed restriction was imposed on growing nor mal and dwarf chickens to follow the subsequent endocrine changes. Since sh ort-term feed restriction of dwarf chickens resulted in decreased plasma IG F-I, it appears that this is not a GH-dependent effect. However, with longe r term undernutrition, IGF-I was not decreased in dwarf chickens. So, after a longer restriction period, the regulation of these factors appears to be come more GH-dependent. IGF-II was not depressed at all by feed restriction in the dwarf chicken, suggesting a degree of GH-dependency.