Carbohydrate metabolism and the temporal occurrence of a serotonin-like indole in the male and female reproductive tract and its relationship with PGF and infertility: a review.

Both in the male and in the female reproductive tract glucose can be converted via either the pentose pathway or the sorbitol pathway. It is shown that a disturbed carbohydrate metabolism can lead to infertility, i.e. in the cow and in the bull semen. Evidence is provided that the serotonin-like indole which occurs in the protein-complex and is liberated, can exert effects on the uterine endometrium comparable to those caused by serotonin. It is suggested that the indole liberated can cause ischaemia, followed by regression of the endometrium. When this occurs in repeat breeder cows, exogenous PGF given in mid-cycle on a suitable day, may restore the endometrium so that the cow can again become pregnant. The possibility is mentioned that in humans the free indole might cause regression of the endometrium and some distress symptoms, but thereafter endogenous PGF does increase the vascular permeability resulting finally in bleeding.