M R Pickard

Thyroid hormone regulates the expression of α-internexin in neurons in culture

Maternal hypothyroidism in the rat compromises &agr;-internexin (&agr;-IN) expression in early fetal brain. We have therefore examined whether 3,5,3′-triiodothyronine (T3) regulates &agr;-IN expression in fetal brain neurons in culture. Cells expressed transcripts encoding T3 nuclear receptor isoforms in a T3-independent manner. &agr;-IN protein abundance was increased in cultures treated with 0.1 and 1 nM T3 for 20 h (177 and 185% control, respectively) and in cultures treated with 1 nM T3 for 40 h (131% control). &agr;-IN transcript abundance was unaffected by T3 treatment. In conclusion, T3 at a physiological level, stimulates &agr;-IN protein, but not mRNA, levels in early differentiating neurons in culture. This supports the hypothesis that maternal thyroid hormone directly regulates early neuronal differentiation.

Regulatory effects of thyroid hormones on amino acid metabolism in the brain: The influence of maternal hypothyroxinemia on brain biochemistry of adult rat progeny

The effects of maternal hypothyroxinemia during pregnancy on brain amino acid metabolism in adult rat progeny were investigated. Normal and partially thyroidectomised dams were mated and the progeny allowed to grow to adulthood. [U-14C]Glutamate, [U-14C]glucose and [4,5-3H]leucine metabolism were determined in cerebral cortical slices, and enzymes associated with glutamate metabolism were assayed in cerebral cortical homogenates.