On the presence of 3H-GABA uptake mechanism in bovine spermatozoa

Diagnosis and Prognosis of Male Infertility in Mammal: The Focusing of Tyrosine Phosphorylation and Phosphotyrosine Proteins

“…Mature spermatozoa cannot fertilize oocytes even if they are motile and physiologically normal . In internally fertilizing animals, mature spermatozoa achieve fertilization competence only after they enter the female genital tract; the alterations of spermatozoa once inside the tract is known as capacitation. , Only capacitated spermatozoa can undergo the acrosome reaction upon binding to the zona pellucida, at which point they become capable of penetrating and fertilizing an egg. − Capacitation confers a series of metabolic and structural modifications to the spermatozoa that are accompanied by changes in membrane fluidity; HCO –3 , Ca 2+ , and cAMP levels; PKA activity; and tyrosine phosphorylation of proteins. ,,,− Studies have demonstrated that tyrosine phosphorylation is upregulated during capacitation. − Other studies have consistently reported a positive correlation between capacitation and protein tyrosine phosphorylation in various mammalian species, including humans, that is correlated with fertilization and male fertility. ,,,− The relationship between capacitation and tyrosine phosphorylation was discovered before the beginning of the 21st century; however, the basic molecular mechanism underlying tyrosine phosphorylation-mediated control of capacitation, the acrosome reaction, and male fertility is still unclear. Our review of the literature showed that four major signaling pathways modulating tyrosine phosphorylation-guided capacitation and the acrosome reaction have been reported, namely the cAMP/PKA-dependent pathway, − ,− receptor tyrosine kinase pathway, , nonreceptor protein tyrosine kinase pathway, and G-protein coupled receptor pathway. − The cAMP/PKA-dependent pathway is the most extensively studied and is more specific to sperm cells; therefore, we discuss in detail the relationship of this pathway with tyrosine phosphorylation, male fertilization, and embryonic development (depicted hypothetically in Figure )…”

GABAergic radioligands labelled with tritium

“…Any discussion of this topic would clearly have to start with the issue of tritium labelling the simple and tiny agonist GABA itself. The availability of [ 3 H] GABA has spawned literally hundreds of published studies of the GABA A and GABA B receptors and a few recent ones are highlighted to illustrate the diversity of its applications 2–6. In an earlier approach to the tritiation of GABA, we and others had originally employed an olefin precursor with catalytic tritiation.…”