You are here:
PROPYLTHIOURACIL (PTU)-INDUCED HYPOTHYROIDISM REDUCES FIELD POTENTIAL AMPLITUDE BUT DOES NOT IMPAIR DENTATE GYRUS LTP IN VIVO.
Citation:
Gilbert, M. E., C. Paczkowski, AND M E. Stanton. PROPYLTHIOURACIL (PTU)-INDUCED HYPOTHYROIDISM REDUCES FIELD POTENTIAL AMPLITUDE BUT DOES NOT IMPAIR DENTATE GYRUS LTP IN VIVO. Presented at Society for Neuroscience, New Orleans, LA, November 4-9, 2000.
Description:
Developmental exposure to hypothyroid-inducing agents leads to reductions in body weight, alterations in hippocampal structure, and impaired performance on a variety of behavioral learning tasks. Electrophysiological properties of the hippocampus in hypothyroid animals, however, have not been well characterized. The present study examined field potentials evoked in the dentate gyrus of offspring of dams rendered hypothyroid from parturition throughout lactation. Pregnant rats were administered 0 or 15 ppm propylthiouracil (PTU) in the drinking water from gestational day 18 until postnatal day 21. Adult male offspring were anesthetized with urethane and electrodes implanted in the perforant path and dentate gyrus. Input/output (I/O) functions were collected to assess the integrity of synaptic transmission. Long-term potentiation (LTP) was then induced by delivering 3 pairs of 4-pulse train bursts (400 Hz) at a stimulus intensity of 300 ?A and I/O functions were re-evaluated 1 hr later. Decrements in population spike and EPSP slope amplitude were observed in baseline I/O recordings of PTU-treated animals relative to controls. This difference was limited to the moderate to high stimulus range. Despite baseline transmission deficits, group differences in LTP magnitude were not evident in posttrain I/O functions. Further testing with higher intensity trains of 1500?A produced elevations in the magnitude of LTP in PTU relative to control animals. These data indicate that developmental hypothyroidism produces persistent alterations in hippocampal synaptic function, while the mechanisms supporting synaptic plasticity in this brain region appear to remain intact. (Does not reflect US EPA policy).