Low level postnatal methylmercury exposure in vivo alters developmental forms of short-term synaptic plasticity in the visual cortex of rat

Journal Article · Sun Nov 01 00:00:00 EDT 2009 · Toxicology and Applied Pharmacology

DOI:https://doi.org/10.1016/j.taap.2009.07.037· OSTI ID:21344781

Dasari, Sameera ^[1]; Yuan, Yukun ^[1]

---

1. Department of Pharmacology and Toxicology, B307A Life Science Building, Michigan State University, East Lansing, MI 48824-1317 (United States)

Methylmercury (MeHg) has been previously shown to affect neurotransmitter release. Short-term synaptic plasticity (STP) is primarily related to changes in the probability of neurotransmitter release. To determine if MeHg affects STP development, we examined STP forms in the visual cortex of rat following in vivo MeHg exposure. Neonatal rats received 0 (0.9% NaCl), 0.75 or 1.5 mg/kg/day MeHg subcutaneously for 15 or 30 days beginning on postnatal day 5, after which visual cortical slices were prepared for field potential recordings. In slices prepared from rats treated with vehicle, field excitatory postsynaptic potentials (fEPSPs) evoked by paired-pulse stimulation at 20-200 ms inter-stimulus intervals showed a depression (PPD) of the second fEPSP (fEPSP2). PPD was also seen in slices prepared from rats after 15 day treatment with 0.75 or 1.5 mg/kg/day MeHg. However, longer duration treatment (30 days) with either dose of MeHg resulted in paired-pulse facilitation (PPF) of fEPSP2 in the majority of slices examined. PPF remained observable in slices prepared from animals in which MeHg exposure had been terminated for 30 days after completion of the initial 30 day MeHg treatment, whereas slices from control animals still showed PPD. MeHg did not cause any frequency- or region-preferential effect on STP. Manipulations of [Ca{sup 2+}]{sub e} or application of the GABA{sub A} receptor antagonist bicuculline could alter the strength and polarity of MeHg-induced changes in STP. Thus, these data suggest that low level postnatal MeHg exposure interferes with the developmental transformation of STP in the visual cortex, which is a long-lasting effect.

• OSTI ID: 21344781
• Journal Information: Toxicology and Applied Pharmacology, Vol. 240, Issue 3; Other Information: DOI: 10.1016/j.taap.2009.07.037; PII: S0041-008X(09)00326-3; Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0041-008X
• Country of Publication: United States
• Language: English

Related Subjects

60 APPLIED LIFE SCIENCES
CALCIUM IONS
CEREBRAL CORTEX
DOSES
IN VIVO
METHYLMERCURY
RATS
RECEPTORS
STIMULATION
STIMULI
TOXICITY
TRANSMISSION
ANIMALS
BODY
BRAIN
CENTRAL NERVOUS SYSTEM
CEREBRUM
CHARGED PARTICLES
IONS
MAMMALS
MEMBRANE PROTEINS
NERVOUS SYSTEM
ORGANIC COMPOUNDS
ORGANIC MERCURY COMPOUNDS
ORGANS
PROTEINS
RODENTS
VERTEBRATES