Effect of ether or ketamine anesthesia on rat uterine estrogen and progesterone receptors

Rat uterine estrogen receptors (ER) and progesterone receptors (PR) have been used as controls in ER and PR assays of breast tumors. Stunning or decapitation of experimental animals without prior anesthesia is no longer acceptable as a method of killing. Thus, we compared the effects of two anesthetics on the concentration of rat uterine ER and PR. Rats were killed by one of three methods: (a) stunning, (b) ether anesthesia followed by decapitation, or (c) ketamine anesthesia followed by decapitation. ER and PR concentrations were determined by titration assay, with dextran-coated charcoal separation, and quantified by Scatchard analysis. No significant differences were found in mean receptor concentrations or dissociation constants for the three groups. The results indicate that there is no residual effect of diethyl ether or ketamine hydrochloride on the binding of either estrogen or progestin to their respective receptors. The use of decapitation after either ether or ketamine anesthesia is appropriate for measuring ER and PR receptors in rat uteri.