In the last decade presence of steroid receptors in the plasma membrane became a new evidence, stimulation of these structres is responsible for the rapid and non-genomic effects of steroid hormones.
This kind of steroid receptors are potentially responsible for chemotactic signaling elicited via surface membrane.
Beta-cyclodextrin carriers are dedicated molecules that bind hydrophobic molecules, such as steroidsand then in the aqueous environment they facilitate the dissolution of the bound ligand. In this way these carriers can induce a steroid rich micro-environment around the cell.
Five structurally close or diverse steroid ligands (testosterone, progesterone, dexamethasone, b-estradiol and hydrocortisone) were tested in this work. Fine funing of molecular structure of steroids and receptors was described.
Chemotactic effect of tetstosterone
Testosterone was chemoattractant over a wide range of concentrations, whileprogesterone and dexamethasone were active only at one concentration (10-5 and 10-6 mg ml-1 respectively) and wereeither neutral or repellent at other concentrations. Hydrocortisone and estradiol were unambiguously chemorepellent.
Our results call attention to the fine molecular recognition capacity of Tetrahymena and to the possible rapid effects of steroid hormones at membrane receptors at a very low evolutionary eukaryotic level.