Abstract
Summary
In steroid–blocked ovariecto–mized rats, increases in serum LH concentrations were induced, both before and after pentobarbital anesthesia, by systemic injections of crude extracts of rat hypothalamic tissue (0.1–2.0 hypothalamic equivalents/rat) or by similar injections of purified porcine luteinizing hormone–releasing hormone (LH–RH) at doses of 0.032–0.080 μg/rat. Increases in serum LH concentrations were greater during pentobarbital anesthesia than they had been in the same animals prior to anesthesia. Under comparable conditions, acid extracts of rat cerebral tissue (2.5 mg equivalents/rat) did not cause an increase in serum LH concentrations. These data reveal an increased responsiveness to LH–releasing activities during pentobarbital anesthesia and suggest that barbiturates probably do not block LH release in the proestrous rat by limiting the pituitary response to such stimuli.
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