Neonatal hypothyroidism alters the kinetic properties of Na+, K+-ATPase in synaptic plasma membranes from rat brain

Neonatal hypothyroidism was induced in rat pups by injecting I-131 within two days of birth and the effects on kinetic properties of Na+, K+-ATPase from synaptic plasma membranes were examined. Neonatal hypothyroidism resulted in a generalized decrease in V-max with ATP, Na+, K+ and Mg2+, together with an increase in the K-m for ATP, appearance of a low affinity component for Na+ and allosteric characteristic for the Mg2+-dependent activity at high Mg2+ concentrations. Binding pattern for Na+ and Mg2+ changed. Our results suggest that impairment of Na+, K+-ATPase activity together with altered kinetic properties could be one of the underlying biochemical mechanism leading to central nervous system (CNS) dysfunctions as a consequence of thyroid hormone deprivation during critical stages of brain development. (c) 2006 Elsevier Inc. All rights reserved.