Effect of high-dose total body irradiation on ACTH, corticosterone, and catecholamines in the rat.

Total body irradiation (TBI) or partial body irradiation is a distinct risk of accidental, wartime, or terrorist events. Total body irradiation is also used as conditioning therapy before hematopoietic stem cell transplantation. This therapy can result in injury to multiple tissues and might result in death as a result of multiorgan failure. The hypothalamic-pituitary-adrenal (HPA) axis could play a causative role in those injuries, in addition to being activated under conditions of stress. In a rat model of TBI, we have established that radiation nephropathy is a significant lethal complication, which is caused by hypertension and uremia. The current study assessed HPA axis function in rats undergoing TBI. Using a head-shielded model of TBI, we found an enhanced response to corticotropin-releasing hormone (CRH) in vitro in pituitaries from irradiated compared with nonirradiated rats at both 8 and 70 days after 10-Gy single fraction TBI. At 70, but not 8 days, plasma adrenocorticotrophic hormone (ACTH) and corticosterone levels were increased significantly in irradiated compared with nonirradiated rats. Plasma aldosterone was not affected by TBI at either time point, whereas plasma renin activity was decreased in irradiated rats at 8 days. Basal and stimulated adrenal steroid synthesis in vitro was not affected by TBI. In addition, plasma epinephrine was decreased at 70 days after TBI. The hypothalamic expression of CRH messenger RNA (mRNA) and hippocampal expression of glucocorticoid receptor mRNA were unchanged by irradiation. We conclude that the hypertension of radiation nephropathy is not aldosterone or catecholamine-dependent but that there is an abscopal activation of the HPA axis after 10 Gy TBI. This activation was attributable at least partially to enhanced pituitary ACTH production.

[The changes of serum cortisol and aldosterone in patients with cancer of vestibular section of larynx after irradiation and with and without surgery]. / Dinamika kortizola i al'dosterona v syvorotke krovi bol'nykh rakom vestibuliarnogo otdela gortani posle luchevogo lecheniia s posleduiushchim khirurgicheskim vmeshatel'stvom i bez nego.

Enzyme immunoassay was used to measure serum levels of hydrocortisone and aldosterone in 85 patients with vestibular laryngeal cancer before treatment and after it. The treatment consisted of either radiation alone or radiation followed by surgery. Pretreatment examination revealed adrenal dysfunction evident from enhanced glucocorticoid and inhibited mineral corticoid activity. Radiotherapy alone or in combination with surgery gave rise to a trend to a decline in glucocorticoid activity and stimulated mineral corticoid activity.

[The effect of high-dose ultraviolet irradiation on sodium, calcium and aldosterone in the blood of calves]. / Pôsobenie nadmerného ultrafialového ziarenia na sodík, vápnik a aldosteron v plazme teliat.

Five Holstein-Friesian calves, from one sire, with prevalent black hair coat pigmentation were used in the experiment. The mean age was 33 days and the mean live weight 51 kg. The animals were exposed free running without interruption for 12 hours to an artificial ultraviolet light in the range of 280-320 nm. The mean doses of radiation was 179.10(-10) J/h/m. One-spot high-pressure mercury discharge lamps Tesla RVK 400 W were used as a radiation source. The dose rate was estimated from measurements by a spectral photometer with filter UG 2 for absorbtion of visible light located at the height of the back of standing calf. Blood samples were collected immediately before the beginning of treatment and after 5, 12, 24, 48 and 72 hours. The blood plasma aldosterone was measured by radioimmunoassays, the levels of sodium, potassium and calcium in blood plasma by flame spectrophotometry. Double classification variance analysis and evaluation according to the Snedecor F-test, the contrast effect test according to Duncan and regression analysis were used for statistical evaluation. Compared to the first sampling, sodium increased significantly after 5 and 12 hours of exposure (Tab. I) to 138.1 and 138.3 mmol/l, respectively. In the subsequent samplings this trend continued up to 72 hours from the beginning of irradiation (140.5 mmol/l). The potassium level did not change statistically significantly. Owing to an excessive irradiation, the calcium concentration increased significantly. The greatest increase occurred after 12 hours of irradiation (from 2.29 mmol/l to 2.61 mmol/l) and after 36 hours from the end of irradiation (2.70 mmol/l).(ABSTRACT TRUNCATED AT 250 WORDS)