Subclinical hypothyroidism in pregnant rats impaired learning and memory of their offspring by promoting the p75(NTR) signal pathway

OBJECTIVE: Maternal hypothyroidism during pregnancy can affect the neurodevelopment of their offspring. This study aimed to investigate the effects of maternal subclinical hypothyroidism (SCH) on spatial learning and memory, and its relationship with the apoptotic factors in cerebral cortex of the offspring. METHODS: Female adult Wistar rats were randomly divided into three groups (n = 15 per group): control (CON) group, SCH group and overt hypothyroidism (OH) group. Spatial learning and memory in the offspring were evaluated by long-term potentiation (LTP) and Morris water-maze (MWM) test. The protein expression of the p75 neurotrophin receptor (p75(NTR)), phospho-c-Jun N-terminal kinase (p-JNK), the pro-apoptotic protein p53 and Bax were detected by Western blotting. RESULTS: The Pups in the SCH and OH groups showed longer escape latencies in the MWM and decreased field-excitatory post synaptic potentials in LTP tests compared with those in the CON group. p75(NTR), p-JNK, p53 and Bax expression levels in the cerebral cortex increased in pups in the SCH and OH groups compared with those in the CON group. CONCLUSIONS: Maternal SCH during pregnancy may impair spatial learning and memory in the offspring and may be associated with the increased apoptosis in the cerebral cortex.