Abstract
Summary
Serum prolactin and LH values were relatively low on the morning of proestrus, but increased remarkably on the late afternoon of proestrus. Peak values for both hormones were reached between 5:30-7:30 p.m., although prolactin began to rise earlier and declined later than LH. Placement of rats under ether anesthesia for about 0.5 min prior to withdrawing blood for radioimmunoassay did not change normal serum prolactin and LH trends, and prolactin values were the same as in unanesthetized rats killed by guillotine. Prolonged pentobarbital anesthesia completely blocked the late afternoon rise in serum prolactin and LH, but prolactin values showed a significant increase 10-30 min after injecting the drug.
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