Developmental Exposure to Perchlorate Alters Synaptic Transmission in Hippocampus of the Adult Rat
نویسندگان
چکیده
BACKGROUND Perchlorate is an environmental contaminant that blocks iodine uptake into the thyroid gland and reduces thyroid hormones. This action of perchlorate raises significant concern over its effects on brain development. OBJECTIVES The purpose of this study was to evaluate neurologic function in rats after developmental exposure to perchlorate. METHODS Pregnant rats were exposed to 0, 30, 300, or 1,000 ppm perchlorate in drinking water from gestational day 6 until weaning. Adult male offspring were evaluated on a series of behavioral tasks and neurophysiologic measures of synaptic function in the hippocampus. RESULTS At the highest perchlorate dose, triiodothyronine (T(3)) and thyroxine (T(4)) were reduced in pups on postnatal day 21. T(4) in dams was reduced relative to controls by 16%, 28%, and 60% in the 30-, 300-, and 1,000-ppm dose groups, respectively. Reductions in T(4) were associated with increases in thyroid-stimulating hormone in the high-dose group. No changes were seen in serum T(3). Perchlorate did not impair motor activity, spatial learning, or fear conditioning. However, significant reductions in baseline synaptic transmission were observed in hippocampal field potentials at all dose levels. Reductions in inhibitory function were evident at 300 and 1,000 ppm, and augmentations in long-term potentiation were observed in the population spike measure at the highest dose. CONCLUSIONS Dose-dependent deficits in hippocampal synaptic function were detectable with relatively minor perturbations of the thyroid axis, indicative of an irreversible impairment in synaptic transmission in response to developmental exposure to perchlorate.
منابع مشابه
GABA-mediated membrane oscillations as coincidence detectors for enhancing synaptic efficacy in the developing hippocampus
Spontaneously occurring neuronal oscillations constitute a hallmark of developmental networks. They have been observed in the retina, neocortex, hippocampus, thalamus and spinal cord. In the immature hippocampus the so-called ‘giant depolarizing potentials’ (GDPs) are network-driven membrane oscillations characterized by recurrent membrane depolarization with superimposed fast action potentials...
متن کاملThe effect of ketamine on synaptic transmission and synaptic plasticity in CA1 area of rat hippocampal slices
The effect of ketamine (1-100 µM), which has NMDA receptor antagonist properties, on synaptic transmission and long-term potentiation (LTP) in CAl area of rat hippocampus was examined in vitro. Field potentials were recorded in pyramidal cell layer following Schaffer collateral stimulation. Primed-burst stimulation (PEs) was used for induction of LTP. The amplitude of population spiks (PS) was ...
متن کاملGABA-mediated membrane oscillations as coincidence detectors for enhancing synaptic efficacy in the developing hippocampus
Spontaneously occurring neuronal oscillations constitute a hallmark of developmental networks. They have been observed in the retina, neocortex, hippocampus, thalamus and spinal cord. In the immature hippocampus the so-called ‘giant depolarizing potentials’ (GDPs) are network-driven membrane oscillations characterized by recurrent membrane depolarization with superimposed fast action potentials...
متن کاملAspirin changes short term synaptic plasticity in CA1 area of the rat hippocampus
Introduction: The prostaglandin E2 (PGE2), a cyclooxygenase (COX) product, play critical roles in the synaptic plasticity. Therefore, long term use of COX inhibitors may impair the synaptic plasticity. Considering the wide clinical administration of aspirin and its unknown effects on information processing in the brain, the effect of aspirin and sodium salicylate on the short term synaptic p...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره 116 شماره
صفحات -
تاریخ انتشار 2008