title: Immunochemical Localization of GABAAReceptor Subunits in the Freshwater Polyp Hydra vulgaris (Cnidaria, Hydrozoa).
abstract: γ-aminobutyric acid (GABA) receptors, responding to GABA positive allosteric modulators, are present in the freshwater polyp Hydra vulgaris (Cnidaria, Hydrozoa), one of the most primitive metazoans to develop a nervous system. We examined the occurrence and distribution of GABAAreceptor subunits in Hydra tissues by western blot and immunohistochemistry. Antibodies against different GABAAreceptor subunits were used in Hydra membrane preparations. Unique protein bands, inhibited by the specific peptide, appeared at 35, 60, ∼50 and ∼52 kDa in membranes incubated with α3, β1, γ3 or δ antibodies, respectively. Immunohistochemical screening of whole mount Hydra preparations revealed diffuse immunoreactivity to α3, β1 or γ3 antibodies in tentacles, hypostome, and upper part of the gastric region; immunoreactive fibers were also present in the lower peduncle. By contrast, δ antibodies revealed a strong labeling in the lower gastric region and peduncle, as well as in tentacles. Double labeling showed colocalization of α3/β1, α3/γ3 and α3/δ immunoreactivity in granules or cells in tentacles and gastric region. In the peduncle, colocalization of both α3/β1 and α3/γ3 immunoreactivity was found in fibers running horizontally above the foot. These data indicate that specific GABAAreceptor subunits are present and differentially distributed in Hydra body regions. Subunit colocalization suggests that Hydra GABA receptors are heterologous multimers, possibly sub-serving different physiological activities.
authors.affiliation: Department of Life and Environment Sciences, University of Cagliari, SS 554, km 4,5, 09100, Monserrato, Cagliari, Italy. aconcas@unica.it.|Neuroscience Institute, National Research Council of Italy (CNR), Cagliari, Italy. aconcas@unica.it.
authors.forename: A
authors.identifier: http://orcid.org/0000-0002-3431-5292
authors.initials: A
authors.lastname: Concas
authors.affiliation: Institute of Biomolecular Chemistry, National Research Council of Italy (CNR), Pozzuoli, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Imperatore
authors.affiliation: Department of Life and Environment Sciences, University of Cagliari, SS 554, km 4,5, 09100, Monserrato, Cagliari, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Santoru
authors.affiliation: Department of Life and Environment Sciences, University of Cagliari, SS 554, km 4,5, 09100, Monserrato, Cagliari, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Locci
authors.affiliation: Neuroscience Institute, National Research Council of Italy (CNR), Cagliari, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Porcu
authors.affiliation: Institute of Biomolecular Chemistry, National Research Council of Italy (CNR), Pozzuoli, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Cristino
authors.affiliation: Institute of Applied Sciences and Intelligent Systems E. Caianiello, National Research Council of Italy (CNR), Pozzuoli, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Pierobon
mesh_terms: D000818:Animals; D005618:Fresh Water; D006829:Hydra; D007150:Immunohistochemistry / Q000379:methods; D009474:Neurons / Q000378:metabolism*; D021122:Protein Subunits / Q000378:metabolism; D011963:Receptors, GABA-A / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D021122:Protein Subunits; D011963:Receptors, GABA-A; D005680:gamma-Aminobutyric Acid
keywords: GABAA receptor subunits; Hydra; Immunohistochemistry; Western blot