Role of neurotransmitters, prostaglandins and glucose on precursor incorporation into the RNA of thyroid slices

Analysis of the protective effects of γ-aminobutyric acid during fluoride-induced hypothyroidism in male Kunming mice

CONTEXT

Compounds to treat hypothyroidism in the absence of cardiac side effects are urgently required. In this regard, γ-aminobutyric acid (GABA) has gained interest due to its anti-anxiolytic, antihypertensive and antioxidant properties, and reported benefits to the thyroid system.

OBJECTIVE

We investigated the ability of GABA to ameliorate fluoride-induced thyroid injury in mice, and investigated the mechanism(s) associated with GABA-induced protection.

MATERIALS AND METHODS

Adult male Kumning mice (N = 90) were exposed to NaF (50 mg/kg) for 30 days as a model of hypothyroidism. To evaluate the effects of GABA administration, fluoride-exposed mice received either thyroid tablets, or low (25 mg/kg), medium (50 mg/kg) or high (75 mg/kg) concentrations of pure GABA orally for 14 days groups (N = 10 each). The effects of low (50 mg/kg); medium (75 mg/kg) and high (100 mg/kg) concentrations of laboratory-separated GABA were assessed for comparison. Effects on thyroid hormone production, oxidative stress, thyroid function-associated genes, and side-effects during therapy were measured.

RESULTS

GABA supplementation in fluoride-exposed mice significantly increased the expression of thyroid TG, TPO, and NIS (P < 0.05), significantly improved the thyroid redox state (P < 0.05), modulated the expression of thyroid function-associated genes, conferred liver metabolic protection, and prevented changes to myocardial morphology, thus reducing side effects. Both pure and laboratory-separated GABA displayed comparative protective effects.

DISCUSSION AND CONCLUSION

Our findings support the assertion that GABA exerts therapeutic potential in hypothyroidism. The design and use of human GABA trials to improve therapeutic outcomes in hypothyroidism are now warranted.

Brain transfer RNA. I. Methylation of newly synthesized tRNA

Present study demonstrates differences between the labeling patterns of rat cerebral cortex and cerebellum. Although the initial rates of synthesis and methylation of tRNA from these two regions of brain are different, their final degree of methylation is the same in both the cases. Differences in the rates of incorporation of radioactivities in both the tissues can be explained by the differences in the rates of equilibrium of the labeled precursors with the pools. Increased incorporation of labeled uridine into cerebral cortical tRNA following dibutyryl cAMP treatment probably resulted from higher uptake of the labeled precursor due to permeability changes.