Comparison of Cortisol Production by Isolated Adrenal Cells from Syrian Hamsters and Guinea-Pigs at Different Incubation Temperatures

Abstract

During acute cold exposure the cortisol production of guinea-pigs and Syrian hamsters is increased, as indicated by elevated plasma cortisol concentrations (1, 2). The augmented formation of corticosteroids obviously favours the resistance to cold. In this respect an intensifying effect of corticosteroids on the calorigenic action of catecholamines has been suggested (2). In the guinea-pig, a non-hibernator, corticosteroidogenesis naturally occurs at a body temperature (Tb) above 36°C. In the Syrian hamster, however, a Tb far below 30°C is not unusual during hibernation. Thus the question arises if there are interspecies differences in corticosteroidogenesis at low body temperatures between the hibernator and the nonhibemator. In order to answer this question cells from adrenals of both species were isolated and stimulated by adrenocorticotropic hormone (ACTH). In addition, the effect of cold acclimation on steroidogenesis of adrenal cells was investigated. Methods Adrenal cells were obtained from guinea-pigs (Cavia aperea porcel/us) weighing 486 ± 41 g (mean ± S.E.M.; n=24, 12m, 12f) and male Syrian hamsters (Mesocricetus auratus) weighing 98 ± 6 g (n=86), kept at lO°C or lOoC, respectively, and a 14L/I0D light-dark cycle for at least four weeks. Mter halothane anaesthesia the animals were killed by decapitation and the adrenals were removed quickly and trimmed free of adherent fat and external connective tissue. Adrenals of one guinea-pig or four Syrian hamsters were used for one preparation. Adrenal cells were isolated using a modified method derived from (3). Adrenals were minced with scissors into small pieces (<0.5 mm3), washed with ice-cold Earle's balanced salt solution (EBSS, pH=7.4) and placed in EBSS containing 5 mg·ml-I collagenase (Sigma: Type I), 0.1 mg·mI-} DNase and 1 mg·mI-1 bovine serum albumin (BSA). The mixture was incubated for 30 min at 37°C with shaking at 60 cycles·min-I. This, like all other incubations was performed under a 95% QV5% COz atmosphere. The enzyme-treated tissue was dispersed by repeated aspiration through 1 ml pipette tips with different diameters. The suspension was filtered through a steel mesh (100 !lm) into conical polystyrol centrifuge tubes. which were centrifuged at loog for 10 minutes at 4°C. The cell pellets