Adult-onset hypothyroidism impairs paired-pulse facilitation and long-term potentiation of the rat dorsal hippocampo-medial prefrontal cortex pathway in vivo.
Thyroid hormones are critical for the maturation and function of the central nervous system. Insufficiency of thyroid hormones in the adulthood causes a wide range of cognitive dysfunctions, including deficits in learning and memory. The present study investigated whether adult-onset hypothyroidism would alter synaptic functions in the dorsal hippocampo-medial prefrontal cortex (mPFC) pathway, a neural pathway important for learning and memory. Adult hypothyroidism was induced by oral administration of 1% (g/l) antithyroid acting drug 6-n-propyl-2-thiouracil (PTU) to adult male Sprague-Dawley rats for 4 weeks. Postsynaptic potentials (PSP) were recorded in the mPFC by stimulating the dorsal hippocampal CA1 region in vivo. Basal synaptic transmission was evaluated by comparing input-output relationships. Paired-pulse facilitation and long-term potentiation were recorded to examine short- and long-term synaptic plasticity. Adult-onset hypothyroidism did not change the basal synaptic transmission, but significantly reduced paired-pulse facilitation and long-term potentiation of PSP. These inhibitions can be restored by thyroid hormone replacement. The results suggest that such alterations in synaptic plasticity of the dorsal hippocampo-mPFC pathway might contribute to understanding basic mechanisms underlying learning and memory deficits associated with adult-onset hypothyroidism.
Sui
L
L
Laboratory of Higher Brain Functions, Institute of Neurobiology, Fudan University, Shanghai, PR China.
Wang
F
F
Li
B M
BM
D000818:Animals; D013956:Antithyroid Agents; D001835:Body Weight / Q000502:physiology; D004558:Electric Stimulation; D004594:Electrophysiology; D019706:Excitatory Postsynaptic Potentials / Q000502:physiology; D006624:Hippocampus / Q000503:physiopathology*; D007037:Hypothyroidism / Q000139:chemically induced / Q000503:physiopathology*; D017774:Long-Term Potentiation / Q000502:physiology*; D008297:Male; D009434:Neural Pathways / Q000502:physiology; D017397:Prefrontal Cortex / Q000503:physiopathology*; D011441:Propylthiouracil; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000502:physiology; D009435:Synaptic Transmission / Q000502:physiology; D013963:Thyroid Hormones / Q000097:blood
D013956:Antithyroid Agents; D013963:Thyroid Hormones; D011441:Propylthiouracil