Median charge and charge heterogeneity of human pituitary FSH, LH and TSH. II. Relationship to sex and age.

The median charge and the degree of charge heterogeneity of FSH, LH and TSH in extracts from pituitaries of 63 individuals were determined by electrophoresis in 0.17% agarose suspension at pH 8.6 followed by hormone analyses by radioimmunoassay. Charge was expressed as migration rate in relation to that of human serum albumin. FSH, LH and TSH showed similar degrees of charge heterogeneity within the pituitary, and this degree of heterogeneity was not related to sex or age. There was a sex- and age-related variation in median charge of FSH and LH but not of TSH. The forms of FSH and LH were more acidic at higher ages and the most acidic forms were found in elderly women. Women 32 to 47 years old had more acidic forms of FSH than those 14 to 20 years of age. The median charge of LH was similar in young men and women, while that of FSH was more basic in young women than in young men. These results indicate that the effect of gonadal feedback on the molecular charge is different for FSH and LH. Studies with neuraminidase-treated pituitary extracts indicated that the sex- and age-dependent variations of the charge on FSH were due to differences in the sialic acid content. The amount of FSH in the pituitary was significantly smaller in men than in women. The contents of TSH and LH in the pituitary were lower in the higher age groups. No such decrease with age was found for FSH.