Metabolic adaptations associated with irreversible glucose loss are different to those observed during under-nutrition.

Abstract In this study the hypothesis that irreversible glucose loss results in an ‘uncoupling’ of the somatotrophic axis (increasing plasma GH levels and decreasing plasma IGF-I) was tested. During periods of negative energy balance the somatotrophic axis respond by increasing plasma GH and decreasing plasma IGF-I levels. In turn, elevated GH repartitions nutrient by increasing lipolysis and protein synthesis, and decreases protein degradation. Irreversible glucose loss was induced using sub-cutaneous injections of phloridizin. Seven non-lactating cows were treated with 8 g/day phloridizin (PHZ) and seven control animals (CTRL, 0 g/day), while being restricted to a diet of 80% maintenance. PHZ treatment increased urinary glucose excretion ( P P P P P  = 0.059). Plasma GH was not different between the two groups ( P  > 0.1), whereas plasma IGF-I levels decreased significantly ( P P  = 0.005), in addition the abundance of hepatic mRNA for both growth hormone receptors (GHR(tot) and GHR(1A)) was also decreased ( P