Catecholamine levels and receptor expression in low protein rat offspring

SUMMARYAims  Low birthweight in humans has been shown to lead to increased resting pulse rate in adult life, suggesting possible increased sympathoadrenal activity. The hypothesis that early growth restriction is associated with permanent alterations in catecholamine metabolism was tested. Methods  Circulating catecholamine concentrations (by radioimmunoassay) and adipocyte adrenoceptor expression from different fat depots (by Western blot) were estimated in 12‐week‐old male offspring of rat dams fed a reduced protein diet during pregnancy and lactation. Results  In the fed state, median (interquartile range) plasma adrenaline concentrations for male control and low protein offspring rats were: 0.65 (0.48–0.86) vs. 1.42 (0.89–1.87) nmol/l ( P  < 0.005), respectively. Equivalent noradrenaline concentrations were: 2.71 (2.16–3.46) vs. 3.45 (3.00–4.28) nmol/l ( P  < 0.05). After 24 h starvation, plasma adrenaline concentrations of controls rose to become similar to those of low protein offspring: 1.03 (0.95–1.31) vs. 1.41 (0.69–1.62) nmol/l ( P  = 0.3), respectively. Noradrenaline concentrations rose in both groups to become similar: 3.84 (3.33–4.54) vs. 4.32 (3.70–6.54) nmol/l ( P  = 0.3). In epididymal adipocytes adrenoceptor expression (relative to that of controls) was: α 2A 0.79 (0.66–0.94) ( P  = 0.08), β 1 2.60 (2.27–3.07) ( P  = 0.04), β 3 1.37 (1.27–1.46) ( P  = 0.02). Similar‐pattern differences in adrenoceptor expression were observed in subcutaneous and intra‐abdominal adipocytes. Conclusions  These results are consistent with the suggestion that long‐term alterations in catecholamine metabolism are present in adult offspring of rats fed a reduced protein diet during pregnancy and lactation.