Activation of NMDA receptors prevents excessive metabolic decrease in hypoxic rat pups

We tested the hypothesis that glutamate NMDA receptors may help maintain metabolic rate and body temperature during acute or chronic hypoxic exposure in newborn rats. We recorded ventilation, metabolism (V˙O2−V˙CO2) and rectal temperature, under normoxia, acute hypoxia (30 min – 12% O2), or following 10 days of chronic hypoxia, in 10 days old male and female rats, receiving saline i.p. injection or the NMDA receptor antagonist MK-801. Acute hypoxia decreased rectal temperature and metabolism, and increased ventilation, and V˙E/V˙O2 and V˙E/V˙CO2 to the same extent in males and females. MK-801 injection amplified the metabolic decrease under acute (in males and females) and chronic (in males) hypoxia, prevented the increase of minute ventilation, while V˙E/V˙O2 or V˙E/V˙CO2 remained constant. Hence, NMDA glutamate receptors help to maintain metabolic rate, minute ventilation and body temperature at a determined level in acute (males and females) and chronic hypoxia (males only).