In vitro administration of 17 beta-estradiol inhibits drug-induced contractions of the rat isolated seminal vesicle

Neuronal signaling repertoire in the mammalian sperm functionality

The common embryonic origin has been a recurrent explanation to understand the presence of "neural receptors" in sperm. However, this designation has conditioned a bias marked by the classical neurotransmission model, dismissing the possibility that neurotransmitters can play specific roles in the sperm function by themselves. For instance, the launching of acrosome reaction, a fundamental sperm function, includes several steps that recall the process of presynaptic secretion. Unlike of postsynaptic neuron, whose activation is mediated by molecular interaction between neurotransmitter and postsynaptic receptors, the oocyte activation is not mediated by receptors, but by cytosolic translocation of sperm phospholipase (PLCζ). Thus, the sperm has a cellular design to access and activate the oocyte and restore the ploidy of the species by an "allogenic pronuclear fusion." At subcellular level, the events controlling sperm function, particularly the capacitation process, are activated by chemical signals that trigger ion fluxes, sterol oxidation, synthesis of cyclic adenosine monophosphate, protein kinase A activation, tyrosine phosphorylations and calcium signaling, which correspond to second messengers similar to those associated with exocytosis and growth cone guidance in neurons. Classically, the sperm function associated with neural signals has been analyzed as a unidimensional approach (single ligand-receptor effect). However, the in vivo sperm are exposed to multidimensional signaling context, for example, the GABAergic, monoaminergic, purinergic, cholinergic, and melatoninergic, to name a few. The aim of this review is to present an overview of sperm functionality associated with "neuronal signaling" and possible cellular and molecular mechanisms involved in their regulation.

High levels of catecholamines in human semen: a preliminary study

The objective of this study was to determine the seminal concentrations of four different catecholamines and their association with semen quality. Seminal concentrations of adrenaline, noradrenaline, 3,4-dihydroxy-phenylalanine (DOPA), and 3,4-dihydroxy-phenyl acetic acid (DOPAC) were determined in 13 healthy volunteers, using high-performance liquid chromatography with an electrochemical detector. In addition, semen analysis was performed. Noradrenaline and DOPA were present in all specimens with a concentration of 15 181+/- 2951 pg ml(-1) and 4023 +/- 429 pg ml(-1) (mean +/- SE), respectively. These concentrations are respectively 19 times (range: 3-44) and twice (range: 1-3) as high as the maximal normal concentration in plasma. Adrenaline was present in 10 and DOPAC in seven of 13 specimens. No correlation was found between the concentration of any of the catecholamines evaluated and semen characteristics. In conclusion, noradrenaline and DOPA are present in human semen at concentrations that are much higher than maximal normal values in plasma. Adrenaline and DOPAC were also found in some of the samples. The concentrations of catecholamines in semen are not associated with semen quality.