Requirements for glucose beyond sperm capacitation during in vitro fertilization in the mouse.
In both the mouse and the human, it is a point of controversy whether glucose is necessary for in vitro fertilization. Some of this controversy has resulted from a failure to distinguish between requirements for glucose during sperm capacitation versus requirements during the multistage process of fertilization. Using the mouse as a model, we performed a series of experiments designed to identify specific processes that might require glucose. We observed a positive correlation between increasing glucose concentrations during capacitation and fertilization, and increasing fertilization of zona pellucida (ZP)-intact eggs. These data supported a requirement for glucose in the fertilization medium even when sperm were first capacitated in the presence of 5.5 mM glucose. This glucose requirement was observed for both ZP-intact and ZP-free eggs. During ZP-free in vitro fertilization, some binding and fusion between the plasma membrane of the sperm and egg occurred in the absence of glucose and at concentrations less than 1 mM, suggesting that this substrate is not absolutely required. However, glucose concentrations of 1 mM or higher greatly facilitated both binding and fusion under these conditions. These subtle distinctions suggest that during ZP-free in vitro fertilization, 1 mM glucose represents a threshold level that facilitates binding and fusion. Taken as a whole, the data suggest requirements for glucose during both capacitation and fertilization under normal physiologic conditions.
Travis
Alexander J
AJ
Center for Research on Reproduction and Women's Health, Philadelphia, PA 19104, USA.
Tutuncu
Levent
L
Jorgez
Carolina J
CJ
Ord
Teri S
TS
Jones
Brian H
BH
Kopf
Gregory S
GS
Williams
Carmen J
CJ
D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D005307:Fertilization in Vitro / Q000187:drug effects*; D005947:Glucose / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D013075:Sperm Capacitation / Q000187:drug effects*; D013084:Sperm-Ovum Interactions / Q000187:drug effects / Q000502:physiology; D015044:Zona Pellucida / Q000502:physiology
D005947:Glucose