Biomedical subjects
Publications and source records attributed to A R Sheth.
Immunoreactive prolactin in high concentration was detected in the human semen. Therefore, the effect of prolactin on the various metabolic parameters of the human spermatozoa was studied. It was found that prolactin brought about many of the biochemical changes in the spermatozoa which are known to be associated with the process of capacitation. These results suggest that prolactin has a role in the sperm capacitation.
The concentration of glycerylphosphorylcholine (GPC) was determined in semen obtained from normal fertile, vasectomized, and vas-reanastomosed subjects. Concentrations of GPC were markedly lower in the semen of vasectomized men. GPC levels observed in vas-reanastomosed subjects were similar to those found in normal fertile men. Vasectomy may not affect GPC synthesis significantly.
The effect of Prolactin and LH on the activity of spermatozoal ATPase was studied. Both the hormones activated the enzyme activity suggesting that these hormones, as they are present in the seminal fluid may influence the energy metabolism of spermatozoa. The spermine, a polyamine present in large concentration in the semen, had significantly enhanced the ATPase activity of the spermatozoa in a dose related manner.
Luteinizing hormone and chorionic gonadotrophin levels were selectively measured by using radioimmunoassays in 98 maternal sera and 116 amniotic fluid samples obtained 10--20 weeks of pregnancy. Levels of hCG in serum were clearly high during 10--14 weeks and thereafter declined gradually. In contrast, serum concentrations of LH during 10--20 weeks were either unmeasurable (less than 1 ng/ml) or lower than those observed during the luteal phase of the menstrual cycle suggesting a decreased responsiveness of pituitary and/or a higher clearance rate for LH during this period of pregnancy. Neither LH nor hCG levels in maternal sera showed significant differences between male and female foetus bearers. A striking similarity was observed between maternal serum and amniotic fluid hCG patterns, despite hCG levels in maternal sera being always higher (1.5--26.9 fold). On the other hand amniotic fluid concentrations of LH became elevated following 12 weeks of gestation while maternal serum LH continued to be at low levels until 20 weeks. Furthermore a sexual dichotomy was observed in amniotic fluid LH concentrations but not in hCG levels during 14--20 weeks of pregnancy, with significantly lower LH levels in male foetus bearers than in female foetus bearers. Of interest is the clear demarcation in LH levels at 16 weeks of gestation. This sequential pattern of change in the concentrations of amniotic fluid LH is similar to those patterns reported by other investigators for foetal serum and pituitary LH during 10--20 weeks of gestation suggesting that the foetus may be the source of the increased levels of LH in amniotic fluid following 12 weeks of pregnancy.
Administration of delta-9-tetrahydrocannabinol (delta 9-THC) to pro-oestrous rats (5 mg/kg and 10 mg/kg, i.p. for 10 days) decreased the hypothalamic LH-RH content. Serum prolactin levels were reduced but serum LH and FSH and pituitary hormone content were similar to values in dioestrous rats. It is suggested that delta 9-THC acts primarily on the hypothalamus.
Using a homogeneous inhibin preparation from human seminal plasma with a molecular weight of about 19 000, a sensitive and specific radioimmunoassay (RIA) for inhibin has been developed. None of the purified hormones tested, such as LH, FSH and prolactin from different species, showed any cross-reaction in this RIA. Steroid hormones such as testosterone, dihydrotestosterone, oestradiol-17 beta and progesterone did not interfere with the assay. The antiserum had an affinity constant (Ka) of 2.379 X 10(9). The assay sensitivity was 10-15 ng per tube and the intra- and inter-assay coefficients of variation were 5-7% (n = 6) and 15% (n = 10) respectively. The recovery for inhibin added to the serum of a castrated man was 95-110%. Using this RIA, inhibin levels in various biological fluids and tissues were measured. Normo-spermic semen contained significantly higher levels of inhibin than did oligospermic semen. Human prostate contained a substantial quantity of inhibin. Monkey semen, rat serum, and bovine, ovine and porcine follicular fluids cross-reacted in the RIA, while ram testicular inhibin and bull semen did not do so. In developing (9-28 days of age) male rats, circulating inhibin levels showed an inverse relationship with serum FSH levels. In female rats of this age endogenous inhibin concentrations changed in parallel with those of serum FSH.
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This communication presents evidence for the existence in the ovine testis of proteinaceous factors which suppress LH as well as FSH. Isolation of these factors has been achieved by using three different procedures: cytosol preparation, metaphosphoric acid extraction and ultrafiltration. Chromatography of cytosol or metaphosphoric acid extract on Sephadex G-75 resulted in separation into three protein fractions designated as G-75-I, II and III in order of their elution. When administered to castrated male rats, Fraction G-75-I suppressed circulatory levels of LH (53% inhibition, P less than 0.05) without altering FSH. The most retarded fraction, G-75-III, suppressed FSH (29% inhibition, P less than 0.001) without any concomitant change in LH. When fraction G-75-III was further fractionated on Sephadex G-25, three components were found and two, G-25-II and G-25-III, were biologically active. These fractions were homogeneous on polyacrylamide disc-gel electrophoresis. The FSH-suppressing factor (inhibin) was heat labile and susceptible to trypsin digestion, indicating that it is proteinaceous. Treatment with urea did not reveal any subunits. The molecular weight of this factor, as determined by gel filtration and SDS-urea gel electrophoresis was estimated to be around 1400-1500. The absence of sialic acid and the molecular weight data suggested that the isolated material was a simple protein and probably a small peptide. Gel filtration on Sephadex G-75 of the metaphosphoric acid extracts of liver, kidney, testis and ovary revealed an identical elution pattern for ovarian and testicular inhibin.
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Sperm motility and metabolism are dependent upon the levels of cyclic AMP. Our studies have demonstrated that spermine by inhibiting sperm phosphodiesterase activity could regulate sperm physiology.
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A new method has been developed to produce antiserum to protein hormones without the use of Freund's complete adjuvant. Antiserum to human chorionic gonadotropin (hCG) was elicited by injecting rabbits with 6 subcutaneous injections of sheep red blood cells (SRBC) coated with hCG. The antiserum produced was observed to be both serologically and biologically active. A small quantity of the hormone (15--20 IU/injection) sufficed to produce hyperimmune sera. This could ensure an overall economy if large amounts of the antisera are required for clinical and diagnostic purposes.