Endocrine responses of protein-malnourished rats infected with Nippostrongylus brasiliensis (Nematoda).

During the course of a primary infection of Nippostrongylus brasiliensis in protein-malnourished rats, plasma concentrations of corticosterone were found to decrease from 0.89 +/- 0.03 at the start of the infection to 0.28 +/- 0.08 mumol/l, 9 days post-infection (p.i.). Similarly, adreno-corticotrophic hormone levels were also observed to fall from 62.09 +/- 12.06 to 20.54 +/- 1.81 by 5 days p.i. and to 35.12 +/- 16.61 nmol/l by 9 days p.i. However, no significant changes were seen in the dry weight of the adrenal glands other than those expected in relation to changes in body weight. Concentrations of both plasma tri-iodothyronine and thyroxine were also severely depleted over the same period from 5.33 +/- 0.34 to 1.09 +/- 0.42 and 104.43 +/- 10.4 to 34.12 +/- 8.95 nmol/l respectively. This was considered not to be due to any change in the capacity of the plasma to bind these hormones. Results for insulin were highly variable, but overall were lower from protein-malnourished rats than results documented for well-nourished rats and a reduction from 18.07 +/- 3.17 to 6.08 +/- 2.18 mu units/ml, 9 days p.i. was observed. The results are discussed in relation to the role of these hormones in protein metabolism in a protein-malnourished animal.