Effects of caffeine supplementation in post-thaw human semen over different incubation periods.

This study aimed to evaluate the effects of caffeine supplementation in post-cryopreservation human semen over different incubation periods. After collection by masturbation, 17 semen samples were analysed according to World Health Organization criteria, processed and cryopreserved with TEST-yolk buffer (1 : 1) in liquid nitrogen. After a thawing protocol, samples were incubated with 2 mm of caffeine for 0, 5, 15, 30 or 60 min, followed by analysis of motility and mitochondrial activity using 3,3'-diaminobenzidine (DAB). Mean variance analysis was performed, and P < 0.05 was the adopted significance threshold. Samples incubated for 15 min showed increased progressive motility compared to other periods of incubation, as well as a reduced percentage of immotile spermatozoa (P < 0.05). In samples incubated for 5 min, increased mitochondrial activity above 50% was observed (DABI and DABII). Although cryosurvival rates were low after the cryopreservation process, incubation with caffeine was associated with an increase in sperm motility, particularly 15-min incubation, suggesting that incubation with caffeine can be an important tool in patients with worsening seminal quality undergoing infertility treatment.

Improvement of metabolic parameters and vascular function by metformin in obese non-diabetic rats.

AIMS: Metformin is an insulin sensitizing agent with beneficial effects in diabetic patients on glycemic levels and in the cardiovascular system. We examined whether the metabolic changes and the vascular dysfunction in monosodium glutamate-induced obese non-diabetic (MSG) rats might be improved by metformin. MAIN METHODS: 16 week-old MSG rats were treated with metformin for 15 days and compared with age-matched untreated MSG and non-obese non-diabetic rats (control). Blood pressure, insulin sensitivity, vascular reactivity and prostanoid release in the perfused mesenteric arteriolar bed as well as nitric oxide production and reactive oxygen species generation in isolated mesenteric arteries were analyzed. KEY FINDINGS: 18-week-old MSG rats displayed higher Lee index, fat accumulation, dyslipidemia, insulin resistance and hyperinsulinemia. Metformin treatment improved these alterations. The norepinephrine-induced response, increased in the mesenteric arteriolar bed from MSG rats, was corrected by metformin. Indomethacin corrected the enhanced contractile response in MSG rats but did not affect metformin effects. The sensitivity to acetylcholine, reduced in MSG rats, was also corrected by metformin. Indomethacin corrected the reduced sensitivity to acetylcholine in MSG rats but did not affect metformin effects. The sensitivity to sodium nitroprusside was increased in preparations from metformin-treated rats. Metformin treatment restored both the reduced PGI2/TXA2 ratio and the increased reactive oxygen species generation in preparations from MSG rats. SIGNIFICANCE: Metformin improved the vascular function in MSG rats through reduction in reactive oxygen species generation, modulation of membrane hyperpolarization, correction of the unbalanced prostanoids release and increase in the sensitivity of the smooth muscle to nitric oxide.