Meeting Abstract
P3.42 Thursday, Jan. 6 Quantification of glucocorticoid and mineralocorticoid receptors in House Sparrow brain and peripheral tissues LATTIN, C.R.*; WALDRON-FRANCIS, K. ; RICHARDSON, J.W.; BREUNER, C.W.; ROMERO, L.M.; Tufts University; Tufts University; Northern Essex Community College; University of Montana; Tufts University christine.lattin@tufts.edu
The hormone corticosterone (CORT) is essential in modulating normal activity levels and metabolism; it also plays a key role in the stress response. Both baseline and stress-induced plasma CORT levels can vary seasonally, between different species, populations, sexes and healthy vs. chronically-stressed animals. Because intracellular corticosterone receptors are found in most tissues throughout the body, one way to better understand this variation in hormone level is by examining receptor density in different tissues. We caught wild House Sparrows and injected them with mitotane to block endogenous CORT production. Thirty-six hours later, sparrows were perfused with ice-cold saline to remove corticosterone binding globulin from tissues, and brain, liver, kidney, spleen, muscle, fat and gonads were flash frozen on dry ice. With radioligand binding assays we identified total capacity, relative density and affinity for intracellular receptors in each tissue. Brain contained high levels of both a low-affinity glucocorticoid receptor (GR) and a high-affinity mineralocorticoid receptor (MR), whereas most other tissues contained high levels of GR and little to no MR. Surprisingly, this included kidney, which contained much more GR than MR (Bmax ~ 400 fmol/mg protein and ~12 fmol/mg protein, respectively). In all tissues, GR and MR affinities were close to published values (Kd ~ 6 nM for GR, and ~ 0.2 nM for MR).
