The effect of a single whole-body irradiation with a lethal dose on catecholamine levels in the pineal glands of rats.

Male Wistar rats adapted to light-dark cycle (LD) 12:12 h were exposed in the darkness to a lethal single dose of 14.35 Gy gamma-rays on the whole body. Irradiation, sham-irradiation and decapitation 30, 60, 120 min after the exposure, were performed between 2000 h and 0100 h in the darkness. The changes in the concentrations of catecholamines (CA) were determined by the radioenzymatic method in the pineal gland of rats. Results were evaluated in comparison with those of the sham-irradiated (30, 60, 120 min) control groups of rats. From the results it follows that the concentration of dopamine (DA) and norepinephrine (NE) in the rat pineal gland significantly decreased 30 and 120 minutes after irradiation (p < 0.01). At min 60 of the postirradiation period it was possible to observe a tendency to recovery of the levels of DA and NE to control values. Epinephrine (EPI) exhibited a significant (p < 0.05) decrease at min 60 and 120 of postirradiation (by 61.8% and 62.8%, respectively).