| Objective To observe the effect of adult-onset hypothyroidism on the expression of munc-18 in dorsal hippocampus and whether the altered proteins could be restored by T4 treatment.Methods All rats were separated into 4 groups randomly: (1) hypothyroidism rats (PTU group), treated intraperitoneally by daily injection of 6-n-propyl-2-thiouracil ( PTU, 1 mg/100 g body weight (BW)) for six weeks; (2) L-T4 treatment rats with common dose (PTU+5-T4 group) were treated by PTU for four weeks following daily intraperitoneal injection of L-T4 (5μg/100g BW) for two weeks; (3) L-T4 treatment rats with high dose (PTU+20-T4 group) were treated as the same protocol as TTC group but the dose of L-T4 (20 ug/100g BW); (4) control rats (control group) were treated with saline solution for six weeks. The radioimmunoassay kits were applied to assay the levels of serum T3 and T4, and immunohistochemical method was used to determine the levels munc-18 in dorsal hippocampi of rats from different groups.Results Compared to the control group, the munc-18 in the PTU group was significantly lower in four layers of CA3 and DG subfields. In the PTU+5-T4 group, munc-18 was restored only in two layers, but in the PTU+20-T4 group munc-18 were restored in all four damaged layers.Conclusion These data suggested that adult-onset hypothyroidism caused layer-specific reductions of munc-18 in dorsal hippocampus, which can be restored by T4 treatment in a dose-dependent manner. |
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