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

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 8g/day phloridizin (PHZ) and seven control animals (CTRL, 0g/day), while being restricted to a diet of 80% maintenance. PHZ treatment increased urinary glucose excretion (P<0.001), resulting in hypoglycemia (P<0.001). As a response to this glucose loss, the PHZ treated animals had elevated plasma NEFA (P<0.005) and BHBA (P<0.001) levels. Average plasma insulin concentrations were not altered with PHZ treatment (P=0.059). Plasma GH was not different between the two groups (P>0.1), whereas plasma IGF-I levels decreased significantly (P<0.001) with PHZ treatment. The decline in plasma IGF-I concentrations was mirrored by a decrease in the abundance of hepatic IGF-I mRNA (P=0.005), in addition the abundance of hepatic mRNA for both growth hormone receptors (GHR(tot) and GHR(1A)) was also decreased (P<0.05). Therefore, the irreversible glucose loss resulted in a partial 'uncoupling' of the somatotrophic axis, as no increase in plasma GH levels occurred although plasma IGF-I levels, hepatic IGF-I mRNA declined, and the abundance of liver GH receptor mRNA declined.

Large-scale double-staining of rat fetal skeletons using Alizarin Red S and alcian blue.

A critical component in the conduct of a prenatal developmental toxicity study is the evaluation of fetal skeletal development. As the developing rodent fetus is typically evaluated at gestation day 20, at a time when ossification of the skeleton is incomplete, a thorough assessment of skeletal development would include both ossified and cartilaginous structures. Current methods to double-stain the fetal skeleton using Alizarin Red S and Alcian Blue are typically described for small sample sizes or using time allotments for each processing step that are unsuitable for industry. In an industrial setting, there is a need for an effective means to double-stain fetal skeletons on a large scale (i.e., hundreds of fetuses simultaneously). This article describes a method used in our laboratory to stain both fetal bone and cartilage using solutions and procedures on an industrial scale.

The metabolism of noradrenaline in the sheep and the effect of dry matter intake upon the production of a metabolite, urinary vanillylmandelic acid.

1. The metabolism of noradrenaline was investigated in the sheep using 3H-noradrenaline injected subcutaneously or intravenously. 2. Analysis of urine collected over 24 hr showed that the bulk of 3H-noradrenaline was rapidly degraded and excreted via the urine. The principle metabolite was the conjugated amine as well as monohydroxy phenyl glycol and vanillylmandelic acid (VMA) previously reported for the rat. 3. Urinary VMA from lambs of two breeds noted for differences in fat (Southdown and Suffolk) increased curvilinearly with dry matter intake and there was a significant breed difference in regression with intake. 4. It is feasible that differences in noradrenaline production could contribute to differences in body composition between breeds.