Aqueous Porcine Pineal Extract: Inhibition of Ovulation Induced with PMSG and HCG in Immature Mice

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Abstract
Extracts of porcine pineal glands inhibited ovulation induced with gonadotropins (PMSG and HCG) in prepuberal mice. Ovulations in mice given gonadotropins plus .0, .125, .25, .5 and 1.0 dose units of crude pineal extract (1.0 dose unit to 1.1 mg extractable protein) averaged 14.0, 9.2, 6.8, 6.0 and 2.9 ovulations per mouse, respectively. This was a significant inhibition over the controls (P<.01). In some cases, ovulation was completely inhibited in mice given a dose unit ≥.25. Mice given similar crude extracts of brain ovulated fully at 12.2, 12.5, 11.5 and 13.9 ovulations per mouse, respectively. These findings indicate that the porcine pineal gland contains an antigonadotropin that is not present in the brain tissues sampled. Injection of saline, melatonin (150 /μg) or fractions of the pineal extract containing substances weighing over 20,000 daltons at .25, .5 and 1.0 dose units (1.0 purified dose unit ≈ 3.6 g fresh pineal tissue) resulted in 13.4, 13.6, 15.1 13.0 and 11.8 ovulations per mouse, respectively. Lack of inhibition of ovulation indicated that the pineal antigonadotropic substance was neither melatonin nor components of the pineal extract weighing in excess of 20,000 daltons. Fractions of pineal extracts devoid of small molecules including melatonin and other indole compounds, exhibited strong antigonadotropic activity. Effects were confined to components of 1,000 to 5,000 daltons. It appears that the active principle is a small peptide. Copyright © 1979. American Society of Animal Science . Copyright 1979 by American Society of Animal Science.