RESUMO
Antidepressants act at the GABA(A) receptor to inhibit GABA-stimulated 36Cl(-) influx and GABA reduction of [35S]TBPS binding. This study examined how selective knock-down (via antisense oligodeoxynucleotides, aODNs) of GABA(A) receptor subunits modified antidepressant activity. The specific aODNs used were for the alpha1, beta1, beta2 or gamma2 subunits of the GABA(A) receptor. The aODN microinjections reduced corresponding GABA(A) receptor subunit mRNA levels by 30-40% as assessed by RT-PCR. The inhibitory effect of the antidepressants amitriptyline and mianserin on GABA-stimulated 36Cl(-) influx was decreased after microinjections of alpha1, beta1, or beta2 subunit aODNs but potentiated after microinjections of gamma2 subunit aODNs. This pattern of aODNs effect on amitriptyline and mianserin modulation of GABA-stimulated 36Cl(-) influx was the same for both antidepressants and similar to GABA but different than that of diazepam and bicuculline. We conclude that multiple subunits of the GABA(A) receptor regulate the effect of amitriptyline and mianserin on the GABA(A) receptor chloride ionophore complex. However, the exact identity of the subunit mediating the direct or allosteric modulation of the antidepressant effect on GABA-stimulated 36Cl(-) influx remains unclear.
Assuntos
Antidepressivos/farmacologia , Córtex Cerebral/efeitos dos fármacos , Canais de Cloreto/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Oligonucleotídeos Antissenso/farmacologia , Receptores de GABA-A/efeitos dos fármacos , Amitriptilina/farmacologia , Animais , Córtex Cerebral/citologia , Córtex Cerebral/metabolismo , Canais de Cloreto/metabolismo , Cloretos/metabolismo , Masculino , Mianserina/farmacologia , Neurônios/citologia , Neurônios/metabolismo , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Receptores de GABA-A/genética , Receptores de GABA-A/metabolismoAssuntos
Serviços Médicos de Emergência/organização & administração , Garantia da Qualidade dos Cuidados de Saúde , Coleta de Dados , Eficiência Organizacional , Sistemas de Comunicação entre Serviços de Emergência , Serviços Médicos de Emergência/normas , Florida , Objetivos Organizacionais , Avaliação de Resultados em Cuidados de Saúde , Indicadores de Qualidade em Assistência à SaúdeRESUMO
GABA(A) receptor function was studied in cerebral cortical vesicles prepared from rats after intracerebroventricular microinjections of antisense oligodeoxynucleotides (aODNs) for alpha1, gamma2, beta1, beta2 subunits. GABA(A) receptor alpha1 subunit aODNs decreased alpha1 subunit mRNA by 59+/-10%. Specific [3H]GABA binding was decreased by alpha1 or beta2 subunit aODNs (to 63+/-3% and 64+/-9%, respectively) but not changed by gamma2 subunit aODNs (94+/-5%). Specific [3H]flunitrazepam binding was increased by alpha1 or beta2 subunit aODNs (122+/-8% and 126+/-11%, respectively) and decreased by gamma2 subunit aODNs (50+/-13%). The "knockdown" of specific subunits of the GABA(A )receptor significantly influenced GABA-stimulated 36Cl- influx. Injection of alpha1 subunit aODNs decreased basal 36Cl- influx and the GABA Emax; enhanced GABA modulation by diazepam; and decreased antagonism of GABA activity by bicuculline. Injection of gamma2 subunit aODNs increased the GABA Emax; reversed the modulatory efficacy of diazepam from enhancement to inhibition of GABA-stimulation; and reduced the antagonist effect of bicuculline. Injection of beta2 subunit aODNs reduced the effect of diazepam whereas treatment with beta1 subunit aODNs had no effect on the drugs studied. Conclusions from our studies are: (1) alpha1 subunits promote, beta2 subunits maintain, and gamma2 subunits suppress GABA stimulation of 36Cl- influx; (2) alpha1 subunits suppress, whereas beta2, and gamma2 subunits promote allosteric modulation by benzodiazepines; (3) diazepam can act as an agonist or inverse agonist depending on the relative composition of the receptor subunits: and (4) the mixed competitive/non-competitive effects of bicuculline result from activity at alpha1 and gamma2 subunits and the lack of activity at beta1 and beta2 subunits.
Assuntos
Córtex Cerebral/metabolismo , Cloretos/metabolismo , Oligodesoxirribonucleotídeos Antissenso/farmacologia , Receptores de GABA-A/genética , Ácido gama-Aminobutírico/farmacologia , Animais , Sequência de Bases , Bicuculina/farmacologia , Córtex Cerebral/efeitos dos fármacos , Flunitrazepam/farmacocinética , Masculino , Fases de Leitura Aberta , Ratos , Ratos Sprague-Dawley , Receptores de GABA-A/fisiologia , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Ácido gama-Aminobutírico/metabolismoAssuntos
Serviços Médicos de Emergência/legislação & jurisprudência , Gestão de Riscos , Educação Continuada , Serviços Médicos de Emergência/normas , Imperícia , Seleção de Pessoal/tendências , Garantia da Qualidade dos Cuidados de Saúde , Qualidade da Assistência à Saúde , Transporte de Pacientes , Estados Unidos , Recursos HumanosRESUMO
A central theme for EMS systems is the reduction of death and disability from emergency illnesses and injuries, with most systems focusing exclusively on treatment to fulfill their missions. Unfortunately, this has often resulted in the neglect or complete disregard of prevention, which actually may be the more powerful intervention strategy. Yet hopefully, as EMS systems begin to learn and embrace the principles of continuous quality improvement (CQI) in their organizational cultures, the advantages of prevention vs. treatment will become more apparent and internally recognized.
