Dexamethasone receptors and their distribution in the brain of the red tilapia

Abstract

Cytosolic extracts of liver and brain showed specific, saturable binding with [3H]dexamethasone: Scatchard plots were linear. Cortisol and 11-deoxycortisol acted as competitors, whilst 17α,20α-dihydroxy-4-pregnen-3-one was relatively much less effective. There was a four-fold range of differences in specific binding capacity between dissected brain regions, the order being telencephalon > hypothalamus > rhombencephalon > optic tectum ≈ (thalamus + tegmentum + torus semicircularis) when Nmax was calculated in terms of DNA content. There was no evidence for any binding of [3H]dexamethasone with membrane fractions.