AJP - Endocrinology and Metabolism, Vol 264, Issue 1 E54-E59, Copyright © 1993 by American Physiological Society
Growth hormone response to GRF and insulin-induced hypoglycemia in Yorkshire and Meishan pigs
M. Bonneau
Institut National de la Recherche Agronomique, Saint Gilles, L'Hermitage, France.
Plasma glucose and porcine growth hormone (GH) responses to insulin and/or
growth hormone-releasing factor (GRF) challenges were determined in
Yorkshire (Y) and Meishan (MS) castrated male pigs at 140 days of age. The
decline in glucose levels observed during the first 30 min after insulin
injection was similar between the two breeds. In Y pigs, GH concentrations
increased sharply after insulin injection. The GH response to insulin was
much smaller in MS than in Y pigs (101 +/- 82 vs. 1,077 +/- 124
ng.min.ml-1, P < 0.001 after 0.30 U/kg insulin). The GH response to GRF
(10 micrograms/kg) did not differ significantly between the two breeds. The
GH response was larger after combined insulin (0.20 U/kg) plus GRF than
after GRF alone in Y pigs (1,512 +/- 229 vs. 463 +/- 401 ng.min.ml-1, P
< 0.05), whereas it did not differ in MS pigs (714 +/- 164 vs. 507 +/-
127 ng.min.ml-1, P > 0.10). The present data demonstrate that the GH
response to insulin is dramatically altered in MS pigs. A possible
explanation to this result is that somatostatin tone would not be depressed
by insulin-induced hypoglycemia in MS pigs.
