Hypoxia and the CNS: Maturation and adaptation at high altitude

The well known circulatory, including hemopoetic, and respiratory adjustments to high altitude often serve as classic examples of adaptation to specific environmental conditions. Less extensively studied are the contributions of the nervous and endocrine systems to such adaptive mechanisms even though their involvement in humans and animals is indisputed. Observations from our and other laboratories have identified in the rat a number of neurologic and endocrine responses to acute and prolonged exposure to high altitude attributable primarily to its hypoxic component. These responses include general retardation in maturation and function of the central nervous system as manifested by alterations in spontaneous and evoked electrical activity particularly in the limbic structures and involving selectively the synapse and are associated with impairment of brain protein and lipid metabolism, myelinogenesis and neurotransmission. Together with these neurologic disturbances, endocrine dysfunctions lead to alterations in growth, fertility and metabolism. Thus hypoxia, even of moderate severity, would affect profoundly the biochemical and functional maturation and activity of the brain and endocrines, and, reciprocally, prevention and treatment of these neuroendocrine imbalances might strengthen the adaptive competence of the individual.