QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

HOME  |   SEARCH  |   ARCHIVE  |   SUBSCRIBE  |   CONTACT  |   HELP

This Article Full Text Full Text (PDF) Submit an eLetter Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (31) Citing Articles via Google Scholar Google Scholar Articles by Bausch, S. B. Articles by Chavkin, C. Search for Related Content PubMed PubMed Citation Articles by Bausch, S. B. Articles by Chavkin, C.

 Previous Article  |  Next Article 

Volume 17, Number 1, Issue of January 1, 1997 pp. 477-492
Copyright ©1997 Society for Neuroscience

Changes in Hippocampal Circuitry after Pilocarpine-Induced Seizures as Revealed by Opioid Receptor Distribution and Activation

Received Feb. 13, 1996; revised Sept. 24, 1996; accepted Oct. 17, 1996.

Suzanne B. Bausch and Charles Chavkin

Department of Pharmacology, University of Washington, Seattle, Washington 98195-7280

The pilocarpine model of temporal lobe epilepsy was used to study the time-dependent changes in dentate gyrus circuitry after seizures. Seizures caused a decrease in µ- and -opioid receptor immunoreactive (MOR-IR and DOR-IR, respectively) neurons in the hilus and MOR-IR neurons in the granule cell layer. Additionally, diffuse DOR-IR, MOR-IR, and GABA immunoreactivities (GABA-IR) were increased in the inner molecular layer. Using the in vitro hippocampal slice preparation to study the physiological consequences of the anatomical changes, we found that the disinhibitory effects of the µ-opioid receptor agonist [D-Ala²,MePhe⁴,Gly-(ol)⁵]-enkephalin (DAMGO) and the GABA_A receptor antagonist bicuculline were greatly depressed 5-13 d after pilocarpine injection but returned to control levels within 6 weeks. The amplitudes of monosynaptic evoked IPSCs and the effects of DAMGO on this parameter were also slightly decreased 5-13 d after pilocarpine injection but significantly increased at 6 weeks. DAMGO significantly decreased the mean amplitude of spontaneous IPSCs (sIPSCs) at 6 weeks after pilocarpine injection but not in controls. The -opioid receptor agonist [D-Pen^2,5]-enkephalin (DPDPE) principally inhibited excitatory transmission in saline-treated animals without affecting either sIPSCs or evoked IPSCs. The DPDPE-induced inhibition of excitatory transmission became more pronounced at 6 weeks after pilocarpine injection. These results illustrate the anatomical reorganization and functional changes in dentate gyrus circuitry evident in an animal model of temporal lobe epilepsy and provide evidence of compensatory changes after trauma to the hippocampal formation.

Key words: dentate gyrus; epilepsy; GABA; hippocampus; mossy fiber sprouting; neurotoxicity; synaptic inhibition; opiate physiology

This article has been cited by other articles:

				S. B. Bausch, S. He, Y. Petrova, X.-M. Wang, and J. O. McNamara Plasticity of Both Excitatory and Inhibitory Synapses Is Associated With Seizures Induced by Removal of Chronic Blockade of Activity in Cultured Hippocampus J Neurophysiol, October 1, 2006; 96(4): 2151 - 2167. [Abstract] [Full Text] [PDF]

				S. B. Bausch and J. O. McNamara Contributions of Mossy Fiber and CA1 Pyramidal Cell Sprouting to Dentate Granule Cell Hyperexcitability in Kainic Acid-Treated Hippocampal Slice Cultures J Neurophysiol, December 1, 2004; 92(6): 3582 - 3595. [Abstract] [Full Text] [PDF]

				M. K. Tallent, S. G. Madamba, and G. R. Siggins Nociceptin Reduces Epileptiform Events in CA3 Hippocampus via Presynaptic and Postsynaptic Mechanisms J. Neurosci., September 1, 2001; 21(17): 6940 - 6948. [Abstract] [Full Text] [PDF]

				J. Doherty and R. Dingledine Reduced Excitatory Drive onto Interneurons in the Dentate Gyrus after Status Epilepticus J. Neurosci., March 15, 2001; 21(6): 2048 - 2057. [Abstract] [Full Text] [PDF]

				S. B. Bausch and J. O. McNamara Synaptic Connections From Multiple Subfields Contribute to Granule Cell Hyperexcitability in Hippocampal Slice Cultures J Neurophysiol, December 1, 2000; 84(6): 2918 - 2932. [Abstract] [Full Text] [PDF]

				H. E. Scharfman, J. H. Goodman, and A. L. Sollas Granule-Like Neurons at the Hilar/CA3 Border after Status Epilepticus and Their Synchrony with Area CA3 Pyramidal Cells: Functional Implications of Seizure-Induced Neurogenesis J. Neurosci., August 15, 2000; 20(16): 6144 - 6158. [Abstract] [Full Text] [PDF]

				S. B. Bausch, T. M. Esteb, G. W. Terman, and C. Chavkin Administered and Endogenously Released Kappa Opioids Decrease Pilocarpine-Induced Seizures and Seizure-Induced Histopathology J. Pharmacol. Exp. Ther., March 1, 1998; 284(3): 1147 - 1155. [Abstract] [Full Text]

				M. L. Simmons, G. W. Terman, and C. Chavkin Spontaneous Excitatory Currents and kappa -Opioid Receptor Inhibition in Dentate Gyrus Are Increased in the Rat Pilocarpine Model of Temporal Lobe Epilepsy J Neurophysiol, October 1, 1997; 78(4): 1860 - 1868. [Abstract] [Full Text] [PDF]

				G. Bing, B. Wilson, P. Hudson, L. Jin, Z. Feng, W. Zhang, R. Bing, and J.-S. Hong A single dose of kainic acid elevates the levels of enkephalins and activator protein-1 transcription factors in the hippocampus for up to 1 year PNAS, August 19, 1997; 94(17): 9422 - 9427. [Abstract] [Full Text] [PDF]

Home  |   Search  |   Archive  |   Subscribe  |   Contact  |   Help