Studies on a Non-Melatonin Pineal Anti-Gonadotrophin

Abstract

Continuing investigation of pineal gland function indicates that the anti-gonadotrophic activity of this organ cannot be attributed solely to the postulated hormone melatonin, the concentration of which is negligible in the pineal body compared to quantities required to produce unequivocal physiological effects. A non-melatonin antigonadotrophic substance recently isolated from bovine pineal glands was further purified by organic solvent extraction, ultrafiltration and gel filtration. Studies of partial blockage of compensatory ovarian hypertrophy in unilaterally ovariectomized Charles River CD-1 mice indicated that this substance is significantly more potent than melatonin in this test system.

Pineal factors other than melatonin

“…The effects differ from those of melatonin, 5-methoxytryptophol, serotonin creatinine sulfate, and arginine vasotocin. In an in vivo bioassay (Sorrentino and Benson (1970)) using the compensatory growth of the remaining ovary after unilateral ovariectomy as an index, Benson et al (1971Benson et al ( , 1972 have shown that melatonin-free extracts of bovine pineals possess an antigonadotropic activity. In this paper the detection and partial purification of some pineal factors other than melatonin are presented.…”

Effect of Gonadotropins on the Reduced Excretion of a Gonadotropin-Inhibiting Substance in the Hypophysectomized Rats

“…Several reports have suggested that a melatonin-free extract of bovine pineal exerts anti-gonadotropic activity (Benson et al, 1972;Cheesman and Faris, 1970;Matthews et al, 1971;Moszkowska, 1965;Neacsu, 1972;Thieblot and Menigot, 1971;Vaughan et al, 1972).…”

Current Status of Pineal Peptides

“…Our initial experiments indicated that the antigonadotropic activity of the pineal could not be attributed solely to the postulated hormone MEL, the concentration of which is negligible in the pineal compared to the quantities required to produce physiological effects [Benson et al, , 1972a. A non-MEL, antigonadotropic substance was purified from bovine pineal glands by organic solvent extraction, ultrafiltration and gel filtration.…”

“…Using pineal extracts comparable to those prepared earlier [Benson et al, 1972a] as well as extraction methods similar to those used in the extraction of hypothalamic peptides, O rts et al [1975] prepared pineal fractions which inhibited fertility in female rats. The authors suggest that the active com pounds are small polypeptides which inhibit the secretion of LH.…”

“…If one takes even a cursory, objective view of the literature, there is ample evidence to convince the reader that certain peptides or other unidentified pineal substances may be considered potentially as important to pineal function as MEL. In pineal extracts several different activities have been observed which cannot be explained on the basis of their content of MEL, 5-methoxytryptophol, 5-hydroxytryptophol or other pineal indoles to which an antigonadotropic activity is ascribed [Thieblot et al, 1967; Moszk ow sk a and E bels, 1971; Benson et al, 1972a;E bels et al, 1973;E bels, 1975O rts, 1977], At this time no known pineal compound satisfies all the classical criteria for a candidate hormone, i.e., a substance produced exclusively in the pineal gland and having a specific functional influence in a distant target organ(s). And whereas the presentation of a review on the status of pineal peptides might at first appear appropriate at this time, it may indeed be premature since the significance of the structurally identified and unidentified 'peptides' found in pineal tissue is not fully understood.…”