Nitric oxide stimulates human sperm motility via activation of the cyclic GMP/protein kinase G signaling pathway.
Nitric oxide (NO), a modulator of several physiological processes, is involved in different human sperm functions. We have investigated whether NO may stimulate the motility of human spermatozoa via activation of the soluble guanylate cyclase (sGC)/cGMP pathway. Sperm samples obtained by masturbation from 70 normozoospermic patients were processed by the swim-up technique. The kinetic parameters of the motile sperm-rich fractions were assessed by computer-assisted sperm analysis. After a 30-90  min incubation, the NO donor S-nitrosoglutathione (GSNO) exerted a significant enhancing effect on progressive motility (77, 78, and 78% vs 66, 65, and 62% of the control at the corresponding time), straight linear velocity (44, 49, and 48 μm/s vs 34, 35, and 35.5 μm/s), curvilinear velocity (81, 83, and 84 μm/s vs 68 μm/s), and average path velocity (52, 57, and 54 μm/s vs 40, 42, and 42 μm/s) at 5 μM but not at lower concentrations, and in parallel increased the synthesis of cGMP. A similar effect was obtained with the NO donor spermine NONOate after 30 and 60  min. The GSNO-induced effects on sperm motility were abolished by 1H-[1,2,4]oxadiazolo-[4,3-a]quinoxalin-1-one (a specific sGC inhibitor) and mimicked by 8-bromo-cGMP (8-Br-cGMP; a cell-permeating cGMP analog); the treatment with Rp-8-Br-cGMPS (an inhibitor of cGMP-dependent protein kinases) prevented both the GSNO- and the 8-Br-cGMP-induced responses. On the contrary, we did not observe any effect of the cGMP/PRKG1 (PKG) pathway modulators on the onset of hyperactivated sperm motility. Our results suggest that NO stimulates human sperm motility via the activation of sGC, the subsequent synthesis of cGMP, and the activation of cGMP-dependent protein kinases.
Miraglia
Erica
E
Department of Genetics, Biology and Biochemistry, University of Torino, Via Santena 5/bis, Turin, Italy.
De Angelis
Federico
F
Gazzano
Elena
E
Hassanpour
Hossain
H
Bertagna
Angela
A
Aldieri
Elisabetta
E
Revelli
Alberto
A
Ghigo
Dario
D
D006152:Cyclic GMP / Q000378:metabolism*; D017869:Cyclic GMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology*; D018160:Receptors, Cytoplasmic and Nuclear / Q000037:antagonists & inhibitors / Q000378:metabolism*; D026422:S-Nitrosoglutathione / Q000494:pharmacology*; D015290:Second Messenger Systems / Q000187:drug effects*; D000071756:Soluble Guanylyl Cyclase; D013081:Sperm Motility / Q000187:drug effects*; D013094:Spermatozoa / Q000187:drug effects* / Q000201:enzymology; D013096:Spermine / Q000031:analogs & derivatives* / Q000494:pharmacology
D020536:Enzyme Activators; D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D018160:Receptors, Cytoplasmic and Nuclear; C091861:spermine nitric oxide complex; D013096:Spermine; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; D017869:Cyclic GMP-Dependent Protein Kinases; D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase; D006152:Cyclic GMP