TY - JOUR
T1 - Long-lasting auditory gating deficit accompanied by GABA B receptor dysfunction in the hippocampus after early-life limbic seizures in rats
AU - Tsai, Min Lan
AU - Crutchley, Melanie
AU - Boyce, Richard
AU - Ma, Jingyi
AU - Boon, Francis
AU - Cain, D. Peter
AU - Leung, L. Stan
N1 - Funding Information:
This study was financially supported by operating grants from the Natural Sciences and Engineering Research Council (Canada) , Canadian Institutes of Health Research ( MOP-64433 ), and a Savoy Foundation studentship to MLT. We thank Dr. W. Froestl (Novartis) for the generous gift of CGP56999A and B. Shen and P. Peloquin for technical assistance.
Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.
PY - 2012/6/25
Y1 - 2012/6/25
N2 - In a previous study, we reported a rat model of early-life limbic seizures which resulted in a loss of GABA B receptor inhibition in the hippocampus. Since gating of auditory evoked potentials in the hippocampus (auditory gating) requires GABA B receptors and spatial behaviors depend on the hippocampus, we hypothesize that rats with early-life limbic seizures manifest deficits of auditory gating and spatial behaviors. Seizure rats were given a single injection of GABA B receptor antagonist CGP56999A (1-1.2mg/kg i.p.) on postnatal day (PND) 15, which induced multiple limbic seizures in 8h; control rats were given saline injection. When tested at 3-9weeks after seizure/control treatment, seizure as compared to control rats showed no difference in finding a hidden platform in the water maze, but were deficient in learning and maintaining consecutive criterion performance in the 8-arm radial arm maze. Auditory gating, as measured by paired-click (conditioning followed by test click) average auditory evoked potentials in the hippocampus, revealed a significant difference between seizure rats and controls. Seizure as compared to control rats showed an increased ratio of the test to conditioning click response as adolescents (50days old) or adults (70days old). Heterosynaptic electric paired-pulse depression of hippocampal population excitatory postsynaptic potential in freely moving rats, a measure of hippocampal GABA B-receptor mediated inhibition, was decreased in seizure as compared to control rats. Seizure as compared to control rats showed increased locomotor activity in a novel open field for the first 10min, and decreased activity at 15-60min. However, auditory prepulse inhibition, a measure of sensorimotor gating, revealed no difference between seizure and control rats. In conclusion, early-life limbic seizures induced a long-lasting deficit in auditory gating, likely caused by GABA B receptor-mediated inhibition loss in the hippocampus. Auditory gating loss is a symptom of schizophrenia, and thus GABA B receptor inhibition loss in the hippocampus provides a mechanism linking early-life seizures to a psychiatric symptom.
AB - In a previous study, we reported a rat model of early-life limbic seizures which resulted in a loss of GABA B receptor inhibition in the hippocampus. Since gating of auditory evoked potentials in the hippocampus (auditory gating) requires GABA B receptors and spatial behaviors depend on the hippocampus, we hypothesize that rats with early-life limbic seizures manifest deficits of auditory gating and spatial behaviors. Seizure rats were given a single injection of GABA B receptor antagonist CGP56999A (1-1.2mg/kg i.p.) on postnatal day (PND) 15, which induced multiple limbic seizures in 8h; control rats were given saline injection. When tested at 3-9weeks after seizure/control treatment, seizure as compared to control rats showed no difference in finding a hidden platform in the water maze, but were deficient in learning and maintaining consecutive criterion performance in the 8-arm radial arm maze. Auditory gating, as measured by paired-click (conditioning followed by test click) average auditory evoked potentials in the hippocampus, revealed a significant difference between seizure rats and controls. Seizure as compared to control rats showed an increased ratio of the test to conditioning click response as adolescents (50days old) or adults (70days old). Heterosynaptic electric paired-pulse depression of hippocampal population excitatory postsynaptic potential in freely moving rats, a measure of hippocampal GABA B-receptor mediated inhibition, was decreased in seizure as compared to control rats. Seizure as compared to control rats showed increased locomotor activity in a novel open field for the first 10min, and decreased activity at 15-60min. However, auditory prepulse inhibition, a measure of sensorimotor gating, revealed no difference between seizure and control rats. In conclusion, early-life limbic seizures induced a long-lasting deficit in auditory gating, likely caused by GABA B receptor-mediated inhibition loss in the hippocampus. Auditory gating loss is a symptom of schizophrenia, and thus GABA B receptor inhibition loss in the hippocampus provides a mechanism linking early-life seizures to a psychiatric symptom.
KW - Auditory gating
KW - Early-life seizures
KW - GABA receptor inhibition
KW - Prepulse inhibition
KW - Radial arm maze
KW - Water maze
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U2 - 10.1016/j.physbeh.2012.03.033
DO - 10.1016/j.physbeh.2012.03.033
M3 - Article
C2 - 22504497
AN - SCOPUS:84860557158
SN - 0031-9384
VL - 106
SP - 534
EP - 541
JO - Physiology and Behavior
JF - Physiology and Behavior
IS - 4
ER -