Modulation of GAP-43 mRNA by GABA and glutamate in cultured cerebellar granule cells

• Published in: Brain research Vol. 783; no. 2; pp. 316 - 325
• Main Authors: Console-Bram, Linda M, Baird, Douglas H, Fitzpatrick-McElligott, Sandra G, McElligott, James G
• Format: Journal Article
• Language: English
• Published: London Elsevier B.V 09.02.1998; Amsterdam Elsevier; New York, NY
• Subjects: 6-Cyano-7-nitroquinoxaline-2,3-dione - pharmacology; Animals; Baclofen - pharmacology; Biochemistry and metabolism; Biological and medical sciences; Blotting, Northern; Cells, Cultured; Central nervous system; Cerebellar culture; Cerebellum; Cerebellum - cytology; Cycloleucine - analogs & derivatives; Cycloleucine - pharmacology; Development; Dizocilpine Maleate - pharmacology; Excitatory Amino Acid Agonists - pharmacology; Excitatory Amino Acid Antagonists - pharmacology; Fundamental and applied biological sciences. Psychology; GABA; GABA Agonists - pharmacology; gamma-Aminobutyric Acid - pharmacology; GAP-43; GAP-43 Protein - genetics; Gene Expression Regulation, Developmental; Glial Fibrillary Acidic Protein - analysis; Glutamate; Glutamic Acid - pharmacology; Granule cell; Immunohistochemistry; In Situ Hybridization; Microtubule-Associated Proteins - analysis; mRNA; Muscimol - pharmacology; N-Methylaspartate - pharmacology; Neurons - cytology; Neurons - drug effects; Neurons - metabolism; Neuroprotective Agents - pharmacology; Northern hybridization; Piperazines - pharmacology; Rats; Rats, Sprague-Dawley; RNA, Messenger - metabolism; Vertebrates: nervous system and sense organs; Cerebellum; Granule cell; BDNF, brain derived neurotrophic factor; GFAP, glial fibrillary acidic protein; MAP-2, microtubule associated protein-2; NGF, nerve growth factor; mRNA; CPP, 3-(2-carboxy-piperazin-4-yl)propyl-1 phosphonic acid; Glutamate; GAP-43, growth-associated protein-43; MK-801, (+)-5-methyl-10,11-dihydro-5 H-dibenzo(a,d)cyclohepten-5,10-iminemaleate; ACPD, 1-aminocyclo-pentane-1 S,3 R-dicarboxyclic acid; GAP-43; BME, Basal Medium Eagle; GABA; Development; AMPA, α-amino-3-hydroxy-5-methylisoxazole-4-propionic acid; CNQX, 6-cyano-7-nitroquinoxaline-2,3-dione; GABA, γ-amino-butyric acid; In situ hybridization; Northern hybridization; NMDA, N-methyl- d-aspartate; Cerebellar culture; Growth associated protein 43; Granule neuron; Rat; Rodentia; Central nervous system; Gene expression; In vitro; Vertebrata; Mammalia; Excitatory aminoacid; Neurotransmitter; Brain (vertebrata)
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/S0006-8993(97)01386-3

Expression of GAP-43 in the cerebellum and selected regions of the brain has been shown to be developmentally regulated. Localization of GAP-43 mRNA within granule cells of the immature and mature rat cerebellum has been demonstrated by in situ hybridization. Higher levels are detected in the neonate compared to the adult. To determine if the cerebellar neurotransmitters, GABA ( γ-amino-butyric acid) and glutamate are involved in the modulation of GAP-43 expression, cultured cerebellar granule cells were exposed to these transmitters. Cultures were treated with glutamate, GABA, or the agonists/antagonists to their receptors in serum-free media for 5–7 days. Analysis of the levels of GAP-43 mRNA by in situ hybridization indicated that a 7-day exposure to GABA (25 and 50 μM) significantly lowered levels of granule cell GAP-43 mRNA. Specific agonists to the GABA A (muscimol) and GABA B (baclofen) receptors produced a decrease similar to that observed for GABA. Results from these studies also indicated that exposure to non-NMDA (CNQX) and NMDA (CPP, MK-801) glutamate receptor antagonists, and a metabotropic receptor glutamate agonist (ACPD), decreased the level of GAP-43 mRNA. The involvement of GABA and glutamate in the modulation of GAP-43 expression was corroborated by Northern hybridization. These studies revealed that a 5-day exposure to GABA decreased the cellular content of GAP-43 mRNA by 21% whereas exposure to glutamate resulted in a 37% increase. Findings from the studies reported here, using an in vitro cerebellar granule cell model, suggest that levels of GAP-43 mRNA, in vivo, are modulated by input from both excitatory glutamatergic mossy fibers and inhibitory GABAergic Golgi interneurons. Thus, modulation of GAP-43 mRNA by these neurotransmitters may influence granule cell maturation during development in the neonate and neuroplasticity in the adult, possibly at the parallel fiber–Purkinje cell synapse.