Altered expression of GABAB receptors in the hippocampus after kainic-acid-induced seizures in rats

• Published in: Brain research. Molecular brain research. Vol. 113; no. 1-2; pp. 107 - 115
• Main Authors: FURTINGER, Sabine, BETTLER, Bernhard, SPERK, Günther
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier 12-05-2003
• Subjects: Animals; Biological and medical sciences; Dentate Gyrus - drug effects; Dentate Gyrus - metabolism; Dentate Gyrus - physiopathology; Down-Regulation - drug effects; Down-Regulation - genetics; Epilepsy - chemically induced; Epilepsy - metabolism; Epilepsy - physiopathology; Excitatory Amino Acid Agonists - pharmacology; gamma-Aminobutyric Acid - metabolism; Gene Expression Regulation - drug effects; Gene Expression Regulation - physiology; Headache. Facial pains. Syncopes. Epilepsia. Intracranial hypertension. Brain oedema. Cerebral palsy; Hippocampus - drug effects; Hippocampus - metabolism; Hippocampus - physiopathology; Kainic Acid - pharmacology; Male; Medical sciences; Nerve Degeneration - chemically induced; Nerve Degeneration - genetics; Nerve Degeneration - metabolism; Nervous system (semeiology, syndromes); Neural Inhibition - drug effects; Neural Inhibition - physiology; Neural Pathways - drug effects; Neural Pathways - metabolism; Neural Pathways - physiopathology; Neurology; Neurons - drug effects; Neurons - metabolism; Protein Subunits - drug effects; Protein Subunits - genetics; Protein Subunits - metabolism; Rats; Rats, Sprague-Dawley; Receptors, GABA-B - drug effects; Receptors, GABA-B - genetics; Receptors, GABA-B - metabolism; RNA, Messenger - drug effects; RNA, Messenger - metabolism; Synaptic Transmission - drug effects; Synaptic Transmission - physiology; Up-Regulation - drug effects; Up-Regulation - physiology; Nervous system diseases; Rat; GABAB receptors; Immunocytochemistry; Epilepsy; Rodentia; Central nervous system; Gene expression; Cerebral disorder; Vertebrata; Experimental disease; Temporal lobe epilepsy; Hippocampus; Receptor downregulation; In situ hybridization; Mammalia; Animal; Central nervous system disease; Gabaergic receptor B; Kainic acid; Hippocampus; Brain (vertebrata)
• ISSN: 0169-328X; 1872-6941
• DOI: 10.1016/s0169-328x(03)00097-4

Epilepsy is closely related to an altered transmission of GABA, the major inhibitory transmitter in the brain. GABA acts through two classes of receptors, ionotropic GABA(A) receptors and metabotropic GABA(B) receptors. Using in situ hybridization, receptor autoradiography and immunocytochemistry, we now investigated temporal changes in the expression the GABA(B)-1 and GABA(B)-2 subunits (GABA(B)-1R and GABA(B)-1R, respectively) in the hippocampus following kainic-acid-induced seizures. Significant decreases (by about 40%) in mRNA levels of both splice variants (a and b) of GABA(B)-1R and of GABA(B)-2R were observed in the principal cell layer of the hippocampus 6-12 h after kainic acid injection in the rat. Whereas mRNA levels in the granule cell layer returned to basal after 24 h, the decreases persisted in sectors CA1 and CA3, presumably due to progressing neurodegeneration. In the sector CA3, GABA(B)-R mRNA levels and GABA(B)-R1 immunoreactivity partially recovered 30 days after the initial kainic acid seizures indicating receptor upregulation in surviving neurons.