Early levothyroxine treatment during maternal subclinical hypothyroidism improves spatial learning of offspring in rats / 中华内分泌代谢杂志

ABSTRACT

Objective To investigate the efficacy and optimal time of levothyroxine (L-T4) treatment in pregnant rats with subclinical hypothyroidism.Methods Female adult Wistar rats were divided into six groups (n =10 per group):control,hypothyroid (H),subclinical hypothyroid (SCH),and SCH treated with L-T4 starting from the tenth,thirteenth,and seventeenth gestational day (GD10,GD13 and GD17),to restore normal thyroid hormone levels.Spatial learning was assessed in progenies by a water maze test and fEPSPs recording.Results Progenies from the SCH and H groups demonstrated significantly longer mean latency in the water maze test and a lower amplification percentage of the fEPSPs' amplitude and slope compared with the offspring of the control group.L-T4 treatment in the GD10 and GD13 groups significantly shortened mean latency and increased the amplification percentage of the fEPSPs' amplitude and slope as compared with the progeny of rats with subclinical hypothyroidism.However,L-T4 treatment in the GD17 group showed only minimal effect on spatial learning of offspring.Conclusion Maternal subclinical hypothyroidism may impair spatial learning in the offspring; L-T4 treatment started early during pregnancy may alleviate this adverse effect.