Determining the Dominant Glucocorticoid in the Mexican Axolotl.

Previous studies have shown that simultaneous injections of T4 and dexamethasone, a synthetic glucocorticoid, can induce metamorphosis at submetamorphic doses. Additionally, stressing axolotls by altering their environmental conditions through lowering of the water levels have also been shown to induce metamorphosis. As such, it is possible that the weak response seen in this study is an indicator of strict regulation of the glucocorticoid response to retain neoteny. In future experiments it might therefore be interesting to measure the catecholamine response to see whether these hormones are also governed by strict regulation or could be used as biomarkers for stress.