Gluconeogenesis-linked glycogen metabolism is important in the achievement of in vitro capacitation of dog spermatozoa in a medium without glucose.
In vitro capacitation of dog spermatozoa in a medium without sugars and with lactate as the metabolic substrate (l-CCM) was accompanied by a progressive increase of intracellular glycogen during the first 2 h of incubation, which was followed by a subsequent decrease of glycogen levels after up to 4 h of incubation. Lactate from the medium is the source for the observed glycogen synthesis, as the presence of [(14)C]glycogen after the addition to l-CCM with [(14)C]lactate was demonstrated. The existence of functional gluconeogenesis in dog sperm was also sustained by the presence of key enzymes of this metabolic pathway, such as fructose 1,6-bisphophatase and aldolase B. On the other hand, glycogen metabolism from gluconeogenic sources was important in the maintenance of a correct in vitro fertilization after incubation in the l-CCM. This was demonstrated after the addition of phenylacetic acid (PAA) to l-CCM. In the presence of PAA, in vitro capacitation of dog spermatozoa suffered alterations, which translated into changes in capacitation functional markers, like the increase in the percentage of altered acrosomes, a distinct motion pattern, decrease or even disappearance of capacitation-induced tyrosine phosphorylation, and increased heterogeneity of the chlorotetracycline pattern in capacitated cells. Thus, this is the first report indicating the existence of a functional glyconeogenesis in mammalian spermatozoa. Moreover, gluconeogenesis-linked glycogen metabolism seems to be of importance in the maintenance of a correct in vitro capacitation in dog sperm in the absence of hexoses in the medium.
Albarracín
J L
JL
Unit of Animal Reproduction, Department of Animal Medicine and Surgery, School of Veterinary Medicine, Autonomous University of Barcelona, Bellaterra, Spain.
Fernández-Novell
J M
JM
Ballester
J
J
Rauch
M C
MC
Quintero-Moreno
A
A
Peña
A
A
Mogas
T
T
Rigau
T
T
Yañez
A
A
Guinovart
J J
JJ
Slebe
J C
JC
Concha
I I
II
Rodríguez-Gil
J E
JE
D000818:Animals; D018929:Cell Culture Techniques; D003470:Culture Media / Q000737:chemistry*; D004285:Dogs / Q000378:metabolism / Q000502:physiology*; D005943:Gluconeogenesis / Q000502:physiology*; D005947:Glucose; D006003:Glycogen / Q000378:metabolism*; D019344:Lactic Acid / Q000008:administration & dosage; D008297:Male; D010648:Phenylacetates / Q000494:pharmacology; D013075:Sperm Capacitation / Q000187:drug effects / Q000502:physiology*; D013094:Spermatozoa / Q000201:enzymology / Q000378:metabolism / Q000502:physiology*
D003470:Culture Media; D010648:Phenylacetates; D019344:Lactic Acid; D006003:Glycogen; C025136:phenylacetic acid; D005947:Glucose