Long-term effects of corticosteroid administration in the tammar wallaby, Macropus eugenii.

Abstract

Blood samples were taken daily for 18 days from six male tammar wallabies (Macropus eugenii) and daily intake and output of nitrogen was determined for each animal. During the first and last 6 days of the experiment tammars were injected daily with 0.5 ml olive oil im. During the middle 6 days they were injected daily with 10 mg cortisol/kg body wt suspended in 0.5 ml olive oil. During the 6 days of cortisol injection, plasma cortisol concentration rose from 66 to 387 ng/ml, plasma glucose rose from 3.40 ± 0.04 to 4.97 ± 0.17 mM and both nitrogen intake and output also rose. There were no changes in plasma urea or amino acid levels. Within 3 days of cortisol administration being terminated, all values fell to their preinjection levels. It thus appears that the tammar wallaby responds to glucocorticoids in a similar way to most other mammals. The nonresponse of the red kangaroo and the considerably reduced response of the quokka suggests that there may be a range of responses to cortisol in the macropod marsupials which clearly warrants further investigation.