Inhibition of Oestrus in the Rat by Extracts of Corpus Luteum. ∗

Abstract

Although no data are recorded, Pereyra 1 (on the guinea pig) and Hisaw 2 (on the rat) pointed out the fact that inhibition of oestrus was obtained by acid alcoholic extracts of corpus luteum, but neither gave details of procedure. Parkes and Bellerby, 3 working on mice, obtained an active preparation by extracting freshly dissected luteal tissue with ether. Macht, et al.,∗ obtained active preparations from de-fatted desiccated luteal tissue both by dilute ethyl alcoholic and by ethyl acetate extraction.

Extraction of the oestrus-inhibiting principle from corpora lutea by means of organic solvents has met with varying degrees of success in this laboratory. Press juice gave positive results but there was a severe local reaction and the activity rapidly disappeared. Consistent positive results were obtained with both methyl alcoholic extraction and acidified methyl alcoholic extraction of fresh luteal tissue obtained from sow ovaries. The luteal tissue was hand dissected within 8 hours after removal of the ovaries. A typical experiment is included to show the general method of extraction which has given the most striking results: 250 gm. freshly shelled corpora lutea are thoroughly hashed and treated gradually with 625 cc, methyl alcohol. After standing from 12 to 15 hours at room temperature with frequent agitation the mixture is strained through muslin and the glandular residue thoroughly expressed. The strained fluid is filtered and the filtrate evaporated before a fan. The residue is suspended in normal saline solution so that 1 cc. represents 10 gm. of fresh corpora lutea. An active extract was also obtained using methyl alcohol containing 1% acetic acid. Control extracts were prepared in the same manner from fresh muscle tissue.