title: GABA expression and regulation by sensory experience in the developing visual system.
abstract: The developing retinotectal system of the Xenopus laevis tadpole is a model of choice for studying visual experience-dependent circuit maturation in the intact animal. The neurotransmitter gamma-aminobutyric acid (GABA) has been shown to play a critical role in the formation of sensory circuits in this preparation, however a comprehensive neuroanatomical study of GABAergic cell distribution in the developing tadpole has not been conducted. We report a detailed description of the spatial expression of GABA immunoreactivity in the Xenopus laevis tadpole brain at two key developmental stages: stage 40/42 around the onset of retinotectal innervation and stage 47 when the retinotectal circuit supports visually-guided behavior. During this period, GABAergic neurons within specific brain structures appeared to redistribute from clusters of neuronal somata to a sparser, more uniform distribution. Furthermore, we found that GABA levels were regulated by recent sensory experience. Both ELISA measurements of GABA concentration and quantitative analysis of GABA immunoreactivity in tissue sections from the optic tectum show that GABA increased in response to a 4 hr period of enhanced visual stimulation in stage 47 tadpoles. These observations reveal a remarkable degree of adaptability of GABAergic neurons in the developing brain, consistent with their key contributions to circuit development and function.
authors.affiliation: Montreal Neurological Institute, McGill University, Montreal, Quebec, Canada.
authors.forename: Loïs S
authors.initials: LS
authors.lastname: Miraucourt
authors.forename: Jorge Santos da
authors.initials: JS
authors.lastname: Silva
authors.forename: Kasandra
authors.initials: K
authors.lastname: Burgos
authors.forename: Jianli
authors.initials: J
authors.lastname: Li
authors.forename: Hikari
authors.initials: H
authors.lastname: Abe
authors.forename: Edward S
authors.initials: ES
authors.lastname: Ruthazer
authors.forename: Hollis T
authors.initials: HT
authors.lastname: Cline
mesh_terms: D000818:Animals; D001921:Brain / Q000254:growth & development / Q000378:metabolism; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D059330:GABAergic Neurons / Q000378:metabolism; D007814:Larva / Q000166:cytology / Q000378:metabolism; D010775:Photic Stimulation; D012160:Retina / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D012677:Sensation / Q000502:physiology*; D013477:Superior Colliculi / Q000254:growth & development / Q000378:metabolism; D014795:Visual Pathways / Q000166:cytology / Q000254:growth & development* / Q000378:metabolism*; D014982:Xenopus laevis / Q000254:growth & development / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D005680:gamma-Aminobutyric Acid