Cyclic adenosine monophosphate-mediated enhancement of vascular endothelial growth factor released by differentiated human monocytic cells: the role of protein kinase a

Objective: Our investigation was designed to examine the signaling pathway involved in the enhancement of vascular endothelial growth factor [VEGF] release by beta -adrenoceptor agonists

Materials and Methods: Human U937 cells differentiated into macrophages were primed with lipopolysaccharide [LPS] in the absence or presence of beta -adrenoceptor agonists and antagonists. The VEGF released and the intracellular cyclic adenosine monophosphate [cAMP] generated were assayed by ELISA. Where necessary, differences between mean values were tested for significance using Student's t test

Results: Isoprenaline, procaterol and salbutamol concentration-dependently enhanced the release of VEGF induced by LPS in U937 cells. R*,R*-[ +/- ]-4-[2-[[2-[3-chlorophenyl]-2-hydroxyethyl]amino]propyl]phenoxyacetic acid [BRL 37344], a selective beta 3-adrenoceptor agonist, did not enhance VEGF release. Using isoprenaline as an agonist, propranolol, ICI 118551 and atenolol produced a parallel rightward shift of the concentration-response curve with no reduction in the maximum response. The -logK[B] values were 8.12 +/- 0.17, 8.03 +/- 0.05 and 7.23 +/- 0.05 for propranolol, ICI 118551 and atenolol, respectively, indicating the possible involvement of both beta 1- and beta 2-adrenoceptor subtypes. Isoprenaline and prostaglandin E2 concentration-dependently increased cAMP generation in U937 cells. Isoprenaline, db-cAMP and 6-Bnz-cAMP, a protein kinase A [PKA] activator, all enhanced VEGF release induced by LPS, and this effect was abolished by KT 5720 and Rp-cAMPS, which are both selective PKA inhibitors, suggesting that PKA is the downstream effector of cAMP activity. 8-CPT-cAMP, a selective activator of the Epac system, had no effect on VEGF release induced by LPS, indicating that the Epac pathway played no role in the release process

Conclusion: In this study, we established that beta[1]- and beta[2] - but not beta[3]-adrenoceptors mediated cAMP-dependent enhancement of VEGF release induced by LPS in differentiated U937 cells, and that PKA was the downstream effector of cAMP activity

Indications of the mechanisms involved in improved sperm parameters by zinc therapy

To determine possible indications of the mechanisms involved in improved sperm parameters by zinc therapy in asthenozoospermic men. Forty-five men with asthenozoospermia [>/= 40% immotile sperm] were randomized into four therapy groups: zinc only: n = 11; zinc + vitamin E: n = 12 and zinc + vitamins E + C: n = 14 for 3 months, and non-therapy control group: n = 8. Semen analysis was done according to WHO guidelines. Malone dialdehyde, tumour necrosis factor-alpha [TNF-alpha], total antioxidant capacity, superoxide dismutase [SOD] and glutathione peroxidase were determined in the semen and serum. Antisperm antibodies IgG, IgM and IgA were evaluated by immunobeads. Sperm chromatin integrity was determined by acid denaturation by acridine orange and sperm apoptosis by light and electron microscopy. The effect of zinc on in vitro induced sperm oxidative stress by NADH was evaluated. Asthenozoospermia was significantly associated with oxidative stress with higher seminal malone dialdehyde [8.8 vs. 1.8 mmol/l, p < 0.001] and TNF-alpha [60 vs. 12 pg/l, p < 0.001], and low total antioxidant capacity [1.8 vs. 8.4, p < 0.01], SOD [0.8 vs. 3.1, p < 0.01] and glutathione peroxidase [1.6 vs. 4.2, p < 0.05], compared to normozoospermia. Zinc therapy alone, in combination with vitamin E or with vitamin E + C were associated with comparably improved sperm parameters with less oxidative stress, sperm apoptosis and sperm DNA fragmentation index [DFI]. On the whole, there was no difference in the outcome measures between zinc only and zinc with vitamin E and combination of vitamins E + C. In the in vitro experiment zinc supplementation resulted in significantly lower DFI [14-29%, p < 0.05] compared to zinc deficiency. Zinc therapy reduces asthenozoospermia through several mechanisms such as prevention of oxidative stress, apoptosis and sperm DNA fragmentation

Ex vivo reactivity of the ovarion vascular bed to noradreualine and carbachol during ovarian hyperstimulation syndrome

To study reactivity of the ovarian vascular bed to noradrenaline and carbachol during an experimentally induced ovarian hyperstimulation syndrome [OHSS] in rabbits. Materials and Rabbits were treated with human menopausal gonadotropin [75 IU] daily for 6 days, followed by human chorionic gonadotropin [2,500 IU] to induce OHSS. The ovarian vascular bed was isolated and perfused with physiological solution and its reactivity to injected noradrenaline and acetylcholine was examined. The mean weight of the hyperstimulated ovary was 2.85 +/- 0.5 g compared to 0.25 +/- 0.1 g for the control rabbits. There was no significant difference in [a] the basal perfusion pressure of the ovarian vascular bed ex vivo; [b] the potency of, or maximum response to, noradrenaline, and [c] agonist dissociation constant or receptor density. Carbachol induced significantly greater vasodilation in ovarian vascular beds from hormone-treated rabbits, indicating a greater role for nitric oxide in this syndrome, as further supported by the observation that NW-nitro-L-arginine methyl ester hydrochloride [L-NAME] was more effective against carbachol-induced response in hormone-treated rabbits. In the rabbit model of OHSS, carbachol produced an increased ex vivo vascular response but noradrenaline did not