The effect of clenbuterol on adrenal function in rats†

Abstract

The use of anabolic agents is illegal in the European Community but the effect of these agents on animal welfare is not well documented. The aim of this study was to evaluate whether the administration of anabolic agents, such as clenbuterol, causes stressful effects in rats, as reflected by the adrenal function. Anabolic doses of clenbuterol (1 mg kg-1, 99% purity) were administered orally by stomach tube daily for 45 d to female Long Evans rats (250-300 g, n = 50). Twenty-five animals were used as controls. Blood samples were collected from the jugular vein in anaesthetised animals (ketamine and xylazine). At the end of the experiment, the animals were sacrificed and the adrenal glands were removed. Hormonal levels were measured by an enzyme immunoassay previously validated for this species. Hormonal levels of cortisol and corticosterone, and histopathological analysis, were used as indicators of the adrenal function. Increased corticosterone and cortisol secretion was found in the treated group (p < 0.001), both in adrenal homogenates and peripheral blood samples, compared with control animals. Higher relative adrenal gland weight (adrenal gland-to-body weight ratio) was also found in the treated group (p < 0.01). The major histopathological finding was the presence of hyperplasia in the adrenocortical cells. It was concluded that the administration of an anabolic dose of clenbuterol causes a hyperstimulation of adrenal gland secretion that could adversely affect animal welfare.

Critical Role of Dorsomedial Hypothalamic Nucleus in a Wide Range of Behavioral Circadian Rhythms

“…Although corticosterone, rather than cortisol, is the predominant adrenal corticosteroid in rats, technical difficulties prevented us from obtaining sufficient corticosterone measurements for statistical analysis. We observed roughly parallel changes in these two hormones, however, consistent with their overlapping biosynthetic pathways (Fauci et al, 1998) and with other studies showing parallel changes in release of corticosterone and cortisol (Illera et al, 1998;Szucs et al, 2001). Melatonin levels were unaffected relative to saline-injected controls at all sample times (Fig.…”

Role of β-Adrenoceptor Signaling in Skeletal Muscle: Implications for Muscle Wasting and Disease

“…Chronic administration of ␤-agonists such as clenbuterol or salbutamol in rats almost invariably produces significant cardiac hypertrophy (78,123,386). Clenbuterol treatment in rats has also been shown to increase cortisol and corticosterone secretions and increase the size of the adrenal glands due to hyperplasia of adrenocortical cells (198).…”

β2-Agonist Clenbuterol Induced Changes in the Distribution of White Blood Cells in Rats

“…Since CLE specifically binds to the β 2 -adrenergic receptor, a G proteincoupled receptor and then activates the heterotrimeric G protein -adenylate cyclase -cAMP productive pathway, CLE would induce directly apoptotic cell death in thymocytes, which would cause the reduction of thymus mass, although there was no significant difference between both groups in the present study. Furthermore, Illera et al (26) showed that anabolic dosage of CLE caused adrenal gland hypertrophy and increased secretions of glucocorticoids such as corticosterone and cortisol in rats. Thus, CLE administration-induced reduction of thymus mass would be partially caused by glucocorticoid-induced apoptotic cell death in thymocytes.…”