RESUMO
Exploring drug targets based on disease-associated molecular mechanisms during development is crucial for the generation of novel prevention and treatment strategies for neurodevelopmental psychiatric conditions. We report that prefrontal cortex (PFC)-specific postnatal knockdown of DISC1 via in utero electroporation combined with an inducible knockdown expression system drives deficits in synaptic GABAA function and dendritic development in pyramidal neurons, as well as abnormalities in sensorimotor gating, albeit without profound memory deficits. We show for the first time that DISC1 is specifically involved in regulating cell surface expression of α2 subunit-containing GABAA receptors in immature developing neurons, but not after full maturation. Notably, pharmacological intervention with α2/3 subtype-selective GABAA receptor positive allosteric modulators during the early postnatal period ameliorates dendritic deficits and behavioral abnormalities induced by knockdown of DISC1. These findings highlight a critical role of DISC1-mediated disruption of postnatal GABA signaling in aberrant PFC maturation and function.
Assuntos
Proteínas do Tecido Nervoso/metabolismo , Receptores de GABA-A/efeitos dos fármacos , Receptores de GABA-A/metabolismo , Animais , Modelos Animais de Doenças , Eletroporação , Feminino , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas do Tecido Nervoso/efeitos dos fármacos , Proteínas do Tecido Nervoso/fisiologia , Neurogênese/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Córtex Pré-Frontal/metabolismo , Subunidades Proteicas , Células Piramidais/metabolismo , Filtro Sensorial/genética , Filtro Sensorial/fisiologiaRESUMO
The 5-HT3 receptor (5-HT3R) is part of a superfamily of ligand-gated ion channels which includes nicotinic acetylcholine receptors (nAChR). cRNA derived from the long isoform cloned mouse 5-HT3R was used to drive expression of 5-HT3Rs in Xenopus oocytes. 5-HT-induced currents were monitored using two-electrode voltage-clamp. Eight nicotinic agonists, including ACh and nicotine, but not alpha-anatoxin, were found to antagonize 5-HT-induced currents. With the exception of 3-(2,4)-dimethoxybenzylidene-anabaseine (DMXB-anabaseine; GTS-21) this antagonism appeared to be competitive since it could be overcome by increasing concentrations of 5-HT. Potency of 5-HT3 antagonism was comparable to reported values for nAChR alpha7 activation. These results confirm the notion of families of receptors and further indicate that strong similarities can exist in some critical binding domains.
Assuntos
Agonistas Nicotínicos/farmacologia , Receptores de Serotonina/efeitos dos fármacos , Antagonistas da Serotonina/farmacologia , Acetilcolina/farmacologia , Animais , Toxinas Bacterianas/farmacologia , Compostos de Benzilideno/farmacologia , Sítios de Ligação , Ligação Competitiva , Compostos Bicíclicos Heterocíclicos com Pontes/farmacologia , Colina/farmacologia , Toxinas de Cianobactérias , DNA Complementar/genética , Iodeto de Dimetilfenilpiperazina/farmacologia , Feminino , Toxinas Marinhas/farmacologia , Camundongos , Microcistinas , Família Multigênica , Nicotina/farmacologia , Oócitos , Técnicas de Patch-Clamp , Piridinas/farmacologia , Receptores Nicotínicos/química , Receptores de Serotonina/química , Receptores de Serotonina/genética , Receptores 5-HT3 de Serotonina , Proteínas Recombinantes de Fusão/antagonistas & inibidores , Relação Estrutura-Atividade , Xenopus laevisRESUMO
The two-electrode voltage-clamp technique was used to evaluate Zn block of current activated by gamma-aminobutyric acid (GABA) in Xenopus oocytes injected with cRNA coding for alpha 1 beta 3 gamma 2, alpha 2 beta 3 gamma 2, or alpha 3 beta 3 gamma 2 subunits of the GABAA receptor (GABAAR). cDNA coded for the human form of alpha 1, alpha 2, beta 3 and gamma 2L subunits. alpha 3 subunit cDNA was obtained from an African green monkey library. Zn significantly inhibited the current evoked by application of GABA. Maximal inhibition was greater in alpha 2- and alpha 3- containing GABAARs than in alpha 1-containing GABAARs (51 +/- 1% and 53 +/- 2% vs 19 +/- 2%, respectively). The IC50 for Zn was smaller in alpha 1 than in alpha 2 or alpha 3 GABAARs (1.2 +/- 0.3 microM vs 7 +/- 1 and 9 +/- 1 microM, respectively). Zn shifted the concentration-response curve of GABA to the right in a parallel manner. These data suggest that Zn reduces the amplitude of current evoked at gamma 2 subunit containing GABAARs through an allosteric mechanism.
