Cyclic Adenosine 3':5'-Monophosphate and Protein Kinase Levels in Developing Bovine Spermatozoa

Abstract

The presence of both cyclic 3':5'-adenosine monophosphate (cAMP) and the enzymes required for its synthesis, degradation, and apparent expression of action have been documented in mammalian spermatozoa. Several studies ) have shown that motility can be induced or maintained by cyclic nucleotides and phosphodiesterase inhibitors in bovine spermatozoa from the cauda epididymidis and that increased rates of respiration and fructolysis occur concomitantly. Advantage was taken in these studies of the fact that the motility of bovine spermatozoa from the cauda epididymidis can be substantially reduced by simple incubation at 37\s=deg\Cin isotonic buffers over a relatively short period of time (several hours). Since bovine spermatozoa from the caput epididymidis resemble quiescent caudal cells in that they are characterized by a virtual absence of motility (Igboeli & Foote, 1968) and low glycolytic rates (D. D. Hoskins, unpublished observations), the question arises as to whether the level of cAMP is a prime determinant in the epididymal development of the capacity for motility and increased metabolic rates. The same question can be asked about the cAMP-dependent protein kinases since these enzymes, present in large amounts in bovine spermatozoa from the cauda epididymidis (Hoskins, Casillas & Stephens, 1972;Garbers et al., 1973b), have been implicated in the physiological expression of all actions of cAMP (Kuo & Greengard, 1969a, b). In this communication, we report the levels of cAMP and cAMP-dependent and -independent protein kinases in bovine spermatozoa from the caput and cauda epididymidis.Cyclic AMP was determined by the method of Gilman (1970) except that commercial bovine heart cAMP-dependent protein kinase (Sigma Chemical Co.) was used as the cAMP-binding protein. Assays were performed on sper¬ matozoa from the epididymides of testes stored overnight at 4CC. A prewarmed (37°C) solution consisting of 42 mM-KCl, 88 mM-NaCl, 5 mM-MgS04, 10 mM-KH2P04 and 10 mM-tris, pH 7-2 was used to isolate, wash, and suspend the spermatozoa. Spermatozoa were obtained from the distal cauda epididymidis by the method of Henle & Zittle (1942) and from the distal portion of the caput, after excess blood vessels had been trimmed away, by gently shaking the 131

Development and initiation of sperm motility in the hamster epididymis

“…The concentration of cyclic AMP phosphodiesterase, which degrades the active AMP 3'-5' into inactive 5', is higher in spermatozoa from the caput epididymidis than in those from the cauda (Stephens, Wang and Hoskins, 1979). The decline of this enzyme activity during epididymal transit increases ATPase activity, and is supposed to be the essential cellular factor inducing sperm motility (Garbers et al, 1971 ;Hoskins, Stephens and Hall, 1974 ;Cascieri, Amann and Hammerstedt, 1976).…”

Androgenic control of the cyclic AMP-dependent protein kinase isoenzymes of the rat epididymis

“…Since protein kinases are also present in the epididymal fluid and spermatozoa (Garbers, First & Lardy, 1973;Hoskins, Stephens & Hall, 1974;Lee & Iverson, 1976;De-eknamkul, 1980;Majumder, 1981), it is essential to wash the chopped tubules before release of the tubular protein kinases by homogenization. For this reason, the results of the present study should not have been affected by contamination by epididymal fluid and spermatozoa, and should therefore be more accurate than those using unwashed tubules (Bernard & Wassermann, 1972;Kuo & Williams, 1979).…”

The epididymis and its role on sperm quality and male fertility

“…Throughout the epididymal lumen, the sperm's intracellular cAMP level increases from the corpus to the cauda (Dacheux and Paquignon, 1980;Hoskins et al, 1974;Pariset et al, 1985), simultaneously with metabolic capacity and ATP production (Inskeep and Hammerstedt, 1982). In addition, and [Ca 2+ ] are key factors of the luminal epididymal fluid, which could directly control intracellular cAMP concentrations in the epididymal spermatozoa and consequently activate protein phosphorylation and motility (Xia et al, 2007).…”