The overall goal of this project is to investigate biochemical mechanism of how tolerance to and physical dependence upon barbiturates develop. The objective of this renewal application will focus on the role of GABAA and GABAB receptors in barbiturate tolerance and dependence. We will continue to utilize a rat model (intracerebroventricular, icv, infusion of pentobarbital) as an experimental model useful for determining how different binding sites [for GABA, benzodiazepines (BZ) and convulsants, e.g., picrotoxin and t-butylbicyclophosphorothionate (TBPS)] of the GABAA receptor complex and GABAB receptors in different regions of the brain are involved in chronic effects of pentobarbital.
The specific aims are designed to test the hypothesis formulated.
Specific Aim I. Characterization of GABAA receptors in different regions of the brain during the development of tolerance to and physical dependence upon pentobarbital. Studies on GABAA receptors in discrete areas of the brain will be the first step in gaining insight into the biochemical mechanisms of barbiturate actions. The investigations will be conducted at different time intervals during the development of tolerance to and physical dependence upon pentobarbital. The results obtained will be compared with those from acutely treated animals. The specific studies are as follows: 1. Biochemical characterization of different binding sites (GABA, BZ, TBPS) of the GABAA receptors; 2. Autoradiographic characterizations of different binding sites (GABA, BZ, TBPS) of the GABAA receptors; 3. In situ hybridization characterization of GABAA receptor subunit mRNA (alpha, beta, gamma, delta); and, 4. Cl- influx - functional characterization of GABAA receptors.
Specific Aim II. Characterization of GABAB receptors in different regions of the brain during the development of tolerance to and physical dependence upon pentobarbital. The specific studies are: 1. Biochemical characterization of ligand binding to GABAB receptors; and 2. Autoradiographic characterization of ligand binding to GABAB receptors.
Specific Aim III. Investigation of GABA release mechanisms in different regions of the brain during the development of tolerance to and physical dependence upon pentobarbital. The release of GABA affected by pentobarbital is intimately related to postsynaptic GABAA receptors and presynaptic GABAB receptors (autoreceptors).
Specific Aim I V. Systematic assessments of the degree of the development of tolerance to and physical dependence upon pentobarbital. The results obtained from these experiments will be correlated with the results derived from those of Specific Aims I-III.
|Jang, C; Ho, I K (2000) N-Methyl-D-aspartate receptor NR1 subunit mRNA level was decreased in rat brain during pentobarbital withdrawal. Neurosci Lett 282:129-32|
|Oh, S; Ho, I K (1999) Changes of [3H]muscimol binding and GABA(A) receptor beta2-subunit mRNA level by tolerance to and withdrawal from pentobarbital in rats. Neurochem Res 24:1603-9|
|Oh, S; Jang, C G; Ma, T et al. (1999) Activation of protein kinase C by phorbol dibutyrate modulates GABAA receptor binding in rat brain slices. Brain Res 850:158-65|
|Jang, C G; Oh, S; Zhu, H et al. (1999) Autoradiography of [3H]glutamate binding during pentobarbital tolerance and withdrawal in the rat. Brain Res Bull 48:99-102|
|Jang, C G; Oh, S; Ho, I K (1998) Changes in NMDAR2 subunit mRNA levels during pentobarbital tolerance/withdrawal in the rat brain: an in situ hybridization study. Neurochem Res 23:1371-7|
|Oh, S; Jang, C G; Ho, I K (1998) Activation of protein kinase C by phorbol dibutyrate potentiates [3H]MK-801 binding in rat brain slices. Brain Res 793:337-40|
|Ito, T; Suzuki, T; Wellman, S E et al. (1996) Pharmacology of barbiturate tolerance/dependence: GABAA receptors and molecular aspects. Life Sci 59:169-95|
|Kimura, T; Kuze, J; Watanabe, K et al. (1996) N3-phenacyluridine, a novel hypnotic compound, interacts with the benzodiazepine receptor. Eur J Pharmacol 311:265-9|
|Ito, T; Suzuki, T; Wellman, S E et al. (1996) Chronic pentobarbital administration alters gamma-aminobutyric acidA receptor alpha 6-subunit mRNA levels and diazepam-insensitive [3H]Ro15-4513 binding. Synapse 22:106-13|
|Ito, T; Suzuki, T; Lim, D K et al. (1995) A novel quantitative receptor autoradiography and in situ hybridization histochemistry technique using storage phosphor screen imaging. J Neurosci Methods 59:265-71|
Showing the most recent 10 out of 32 publications