Determinants of insulin responsiveness in young women: Impact of polycystic ovarian syndrome, nitric oxide, and vitamin D.

BACKGROUND: Polycystic ovary syndrome (PCOS) is associated with incremental risk of atherosclerosis and possibly of cardiovascular events. Insulin resistance (IR) occurs frequently in PCOS subjects, which might be one of the mechanisms involved in engendering such risk. We sought to evaluate whether the impact of other factors potentially associated both with PCOS and with IR might differentially modulate degree of IR in women with and without PCOS. METHODS AND RESULTS: We measured body mass index (BMI), hs-CRP, plasma concentrations of asymmetric dimethylarginine (ADMA), vitamin D (25(OH)D3) levels and platelet responsiveness to nitric oxide donor sodium nitroprusside (NO responsiveness) in 47 young women (n=27 with PCOS and n=20 weight-matched controls) without metabolic syndrome, hypertension or overt cardiovascular disease. We performed univariate and multivariate regression analyses to establish correlates of the quantitative insulin-sensitivity check index (QUICKI), as a marker of IR. On univariate analysis, plasma 25(OH)D3 levels and low NO responsiveness tended to be direct correlates with QUICKI in the entire subject group. BMI, hs-CRP, and ADMA levels were significant inverse correlates of QUICKI in PCOS subjects, but not in subjects without PCOS. On multivariate analysis, NO responsiveness, and 25(OH)D3 levels, but not PCOS per se were significant correlates of QUICKI. CONCLUSIONS: In the entire cohort of young women, low NO responsiveness and vitamin D deficiency are associated with low QUICKI, while elevated ADMA, inflammatory activation and obesity are selectively associated with low QUICKI in PCOS subjects; this may contribute to the increased cardiovascular risk associated with this syndrome.

Sperm antimotility properties of a seed extract of Abrus precatorius.

This study examined the inhibitory effects of a methanol extract of Abrus precatorius seeds on the motility of washed human spermatozoa. The extract caused a concentration-related impairment of percentage sperm motility; with the EC50 concentration being 2.29 mg/ml. This effect on motility was essentially irreversible. With the highest concentration tested (20.0 mg/ml), the onset of the antimotility action was almost immediate. In addition, this concentration impaired the functional integrity of the plasma membrane (hypoosmotic swelling test) and viability (nigrosin-eosin stain) of spermatozoa. In contrast, with a lower concentration (5.0 mg/ml), such effects were not evident. It is concluded that at the lower concentrations the antimotility action may result from a rise in intracellular calcium (not via influx) and/or a decline in cAMP content and/or enhanced generation of a reactive oxygen species.

PIP: Researchers from the University of Colombo in Sri Lanka produced a methanolic extract from the seeds of Abrus precatorius to determine if it could produce an inhibitory effect on sperm motility. Concentrations of 1.25 and 2.5 mg/ml of the extract significantly reduced motility after 60 minutes of incubation (p/001). Further concentrations of 5 mg/ml caused the same significant level of impairment as 1.25 and 2.5 mg.ml concentrations (p.001), but at 30 minutes rather than 60 minutes. Moreover concentrations of 10 and 20 mg/ml significantly prevented motility almost immediately (p.001). In fact, at 20 mg/ml concentrations, motility completely stopped at 0 minutes in 3 of the 9 samples and, by 5 minutes, it stopped motility in an additional 5 samples. None of the samples exhibited mobile sperm at 15 minutes at 20 mg/ml concentrations. The extract could produce sperm antimotility activity at the EC50 concentration of 2.29 mg/ml. In addition, after washing, the researchers observed that the antimotility effect was basically irreversible. The highest concentration (20 mg/ml) impaired the functional integrity of the plasma membrane and viability of spermatozoa. This did not happen at the lower concentrations. Instead, the researchers found that a rise in intracellular calcium, and/or a fall in cAMP content, and/or enhanced generation of a reactive oxygen species may have caused the antimotility action at the lower concentrations. In conclusion, scientists can use the seeds of A. precatorius to isolate bioactive compounds with contraceptive abilities.