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

Area of Science:

• Neuroscience
• Physiology
• Developmental Biology

Background:

• Hypoxia poses significant risks to newborns, affecting metabolic rate, body temperature, and respiratory function.
• Glutamate NMDA receptors are crucial for neuronal function and plasticity, but their role in hypoxic adaptation is not fully understood.

Purpose of the Study:

• To investigate the role of glutamate NMDA receptors in maintaining metabolic rate, body temperature, and ventilation in newborn rats exposed to acute and chronic hypoxia.
• To determine if NMDA receptor antagonism impacts physiological responses to hypoxia differently in males and females.

Main Methods:

• Newborn rats (10 days old) were exposed to normoxia, acute hypoxia (12% O2 for 30 min), or chronic hypoxia (10 days).
• Physiological parameters including ventilation, metabolism (oxygen consumption and carbon dioxide production), and rectal temperature were recorded.
• Rats received either saline or the NMDA receptor antagonist MK-801 via intraperitoneal injection.

Main Results:

• Acute hypoxia decreased rectal temperature and metabolism, and increased ventilation in both sexes.
• MK-801 amplified metabolic decline under acute and chronic hypoxia (in males) and prevented the rise in minute ventilation.
• The ratio of ventilation to oxygen consumption or carbon dioxide production remained constant with MK-801, despite altered ventilation and metabolism.

Conclusions:

• Glutamate NMDA receptors play a vital role in maintaining metabolic rate, minute ventilation, and body temperature during acute hypoxia in both male and female newborn rats.
• NMDA receptors are also important for maintaining these parameters during chronic hypoxia, particularly in males.
• NMDA receptor antagonism exacerbates the negative effects of hypoxia on metabolism and ventilation in developing rats.