Wounding alters blood chemistry parameters and skin mineralocorticoid receptors in house sparrows (Passer domesticus).

Because skin is an important physical barrier against pathogens, the ability to quickly and effectively heal wounds directly impacts an animal's health. The hormone corticosterone (CORT) has many complex effects on immune function and can slow wound healing. It has been suggested that CORT's role during wound healing may be to act as a "brake" on inflammation and cell proliferation. This project aimed to clarify the role of CORT in the healing process by quantifying concentrations of its two intracellular receptors, glucocorticoid receptors (GR) and mineralocorticoid receptors (MR), in the skin of wounded (n = 9) or unwounded (n = 8) house sparrows (Passer domesticus) using radioligand binding assays. We also quantified GR and MR in liver, spleen and pectoralis muscle, as well as several blood chemistry parameters, hypothesizing that wounding would alter whole-body energy use. One day post-wounding, wounded birds had higher blood glucose and lower aspartate aminotransferase (a marker indicating muscle damage or catabolism) compared to controls, which may be related to animals' changing metabolic needs in response to lymphocyte and macrophage recruitment at the wound site. Birds had significantly decreased MR, but not GR, in the skin of wounded legs compared to the skin of unwounded legs. There was also a trend towards lower MR in wounded skin compared to unwounded birds. Receptors in the three other tissues did not differ between groups. This study suggests that decreasing the skin's sensitivity to CORT immediately after wounding may be a necessary part of the normal healing process in wild birds.