ALTERATION OF THE COUNTERREGULATORY HORMONES IN THE CONSCIOUS RAT AFTER PROTEIN-ENERGY RESTRICTION

We have recently reported that in rats submitted to protein-energy res triction early in life, an increased insulin efficiency upon the whole -body glucose utilization rate may be one reason for their chronic mil d basal hypoglycaemia. However, the basis for their low plasma glucose level may also lie in the impaired activation of one or several of th e counterregulatory hormones that prevent or correct hypoglycaemia. Ou r study was therefore designed to compare glucose counterregulatory me chanisms in restricted and control rats, both in the basal postabsorpt ive state and at controlled high plasma insulin level and standardized low glycaemic level (hypoglycaemic-hyperinsulinaemic glucose clamps p erformed in conscious rats). When tested in the basal postabsorptive s tate, the restricted rats exhibited prominent increases in the plasma levels of epinephrine (4.5 fold), norepinephrine (3.4 fold) and glucag on (1.7 fold). This was in the presence of significant decreases of pl asma growth hormone and corticosterone levels (by 59 and 32 %, respect ively). With respect to the responses to acute severe hypoglycaemia (2 .5 mmol/l), the glucagon, epinephrine and norepinephrine plasma levels in the restricted rats increased to values similar to those in contro ls. Also, the corticosterone level increased but remained significantl y lower (p<0.001) compared to the control response. The plasma growth hormone level was not significantly affected by acute hypoglycaemia in the restricted or in the control groups. We conclude that protein-ene rgy restriction, starting early in life in the rat, severely impairs t he release of counterregulatory hormones that defend against hypoglyca emia.