Metabolic depression is a common strategy used during stressful environmental conditions, allowing animals to survive for prolonged periods on limited endogenous fuel stores; yet, the mechanisms involved in regulating metabolic depression are poorly understood. The endogenous opioid system (EOS) has been implicated in the regulation of metabolism during hibernation in vertebrates, and we hypothesized that opioids also may regulate metabolic rate during aestivation in the Green-Striped Burrowing Frog, Cyclorana (Litoria) alboguttata (Gunther, 1867). When incubated in the presence of opioid agonists, liver and muscle tissue slices from C. alboguttata underwent tissue- and agonist-specific metabolic depression, and the effect of opioid agonists on metabolism was more pronounced in tissue slices from aestivating animals. Gene transcript levels for the δ-opioid receptor remained constant in the brain and muscle of aestivating C. alboguttata compared with that of active frogs, as did brain transcript levels of the opioid receptor XOR1. The results of this study demonstrate that opioids can influence metabolic rate in isolated tissues from C. alboguttata. The maintenance of key opioid receptor gene transcript levels in tissues of aestivating frogs suggests that despite the energetic costs, maintenance of receptor abundance is important. We propose that the maintenance of opioid receptor abundance during aestivation in C. alboguttata is indicative of a role for the EOS in the regulation of metabolic rate during aestivation.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.
Vol. 47 • No. 2