Shafiq A. Khan

Interleukin-1 inhibits follitropin-induced aromatase activity in immature rat Sertoli cells in vitro

The effects of recombinant preparations of human interleukin-1 (IL-1) on basal and follitropin (FSH)-stimulated aromatase activity of immature rat Sertoli cells in vitro were studied. Sertoli cells were isolated from 7- to 10-day-old rats and cultured for 72 h at 32 degrees C in the presence or absence of test materials. The cells were then washed and cultured for a further 24 h with different doses of FSH in the presence or absence of IL-1. Neither IL-1 alpha nor IL-1 beta had any effect on basal aromatase activity. IL-1 beta inhibited FSH-stimulated aromatase activity in a dose-dependent manner while IL-1 alpha had no significant effect. The inhibitory influence of IL-1 beta on FSH-stimulated aromatase activity was greater when IL-1 beta was present in low concentrations (0.5 and 1.0 U) during the initial 72 h culture period and a further 24 h incubation with IL-1 beta did not cause a further inhibition. When the cells were cultured for 72 h in the presence of both IL-1 alpha and IL-1 beta, the inhibition of FSH-stimulated aromatase was higher than that obtained with IL-1 beta alone. The inhibitory activity of IL-1 beta was blocked by a specific IL-1 beta antiserum. Furthermore, IL-1 beta caused a significant inhibition of cAMP production in Sertoli cells and did not influence dibutyryl-cAMP-stimulated aromatase activity under identical experimental conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Peptides of postulated inhibin activity: Lack of in vitro inhibin activity of a 94-residue peptide isolated from human seminal plasma, and of a synthetic replicate of its C-terminal 28-residue segment

A 94‐residue polypeptide isolated from human seminal plasma and its chemically synthesized C‐terminal 28‐residue segment were studied in an in vitro inhibin bioassay utilizing rat pituitary cell cultures. Both peptides have previously been claimed to have inhibin activities, and the effects on the secretion and cellular content of gonadotrophins (FSH and LH) were now assessed in the in vitro assay. No inhibition was found. After 72 h of culture, both the cellular content and the spontaneous as well as the LHRH‐stimulated release of bioactive or immunoactive FSH and LH remained unaffected. Similarly, no effects were found on the storage and/or release of prolactin, growth hormone, or thyrotropin. We conclude that both the native 94‐residue peptide and the synthetic replicate of its C‐terminal 28‐residue segment, do not influence the pituitary FSH secretion when assessed in this in vitro system.

Molecular composition of luteinizing hormone and follicle-stimulating hormone in commercial gonadotropin preparations.

The biologic (B) and immunologic (I) properties of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were studied in three commercial urinary gonadotropin preparations and in the first international standard preparation of human urinary gonadotropins before and after fractionation by isoelectrofocusing (IEF). Significant differences were found in the IEF profiles of both bioactive and immunoreactive LH and FSH and in the B/I ratios of the preparations studied. The observed differences in the molecular composition of LH and FSH seem to be attributable to the purification procedures employed. The possible influence of these differences on the in vivo potencies, circulating half-lives, and clinical effects of gonadotropin preparations are discussed.