Catecholamine Release and Excretion in Rats with Immunologically Induced Preganglionic Sympathectomy

Abstract

Plasma and urinary catecholamines were quantified to assess global sympathoadrenal function in rats with preganglionic lesions caused by antibodies to acetylcholinesterase (AChE). Rats were given intravenous injections of normal mouse IgG or murine monoclonal anti-acetylcholinesterase IgG (1.5 mg). Five or 16 days afterward, basal blood samples were taken through indwelling arterial cannulae. A few hours later, the rats were immobilized for 10 min in padded restrainers, and another blood sample was drawn. HPLC determinations showed low basal levels of norepinephrine and epinephrine (<0.2 ng/ml in all rat plasma samples). In control rats, immobilization stress increased levels of plasma catecholamines up to 35-fold. In rats tested 5 days after injection of antibody, the norepinephrine response was much smaller (15% of control), and the epinephrine response was nearly abolished (5% of control). There was some recovery at 16 days after antibody treatment, but stress-induced catecholamine release was still markedly impaired. Reduced stress-induced release was not accompanied by major changes in tissue epinephrine or norepinephrine (heart, spleen, adrenal glands, and brain), although adrenal dopamine content dropped by 60%. Urinary excretion was studied in parallel experiments to gain insight into the effects of AChE antibodies on basal syrnpathoadrenal activity. Epinephrine, norepinephrine, dopamine, and selected metabolites were quantified in 24-h urine samples collected at frequent intervals for 30 days after antibody injection. No statistically significant changes were detected in the urinary output of doparnine, 3-methoxytyramine, normetanephrine, or 3methoxy-4-hydroxyphenylglycol. On the other hand, epinephrine and norepinephrine output increased sharply at the time of antibody injection and then fell significantly below control levels. Norepinephrine output returned to normal after 2 weeks, but epinephrine output remained depressed. These results are consistent with previous evidence of widespread and persistent antibody-mediated damage to the preganglionic sympathetic system.

Maternal Perinatal Undernutrition has Long-Term Consequences on Morphology, Function and Gene Expression of the Adrenal Medulla in the Adult Male Rat

“…However, the adrenaline/noradrenaline ratio in plasma was not affected in FR50 compared with control rats (1.73 ± 0.12 in control versus 1.65 ± 0.14 in FR50). Because decapitation and even other disturbances such as handling or transfer of animals produce marked increase in plasma levels of adrenaline and noradrenaline (44–46), we have also measured urinary catecholamine excretion. Catecholamine levels in urine provide an integrated assessment of adrenal medullary function when measured over an acclimatisation period and reduce the risk of stress associated with manipulations.…”