RESUMEN
How general anesthesia interferes with sensory processing to cause amnesia remains unclear. Here, we show that activation of a learning-associated immediate early gene in rat olfactory cortices is uninterrupted by propofol, an intravenous general anesthetic with putative actions on the inhibitory GABAA receptors. Once learned under anesthesia, a novel odor can no longer re-activate the same high-level transcription programming during subsequent conscious relearning. Behavioral tests indicate that the animals' ability to consciously relearn a pure odorant, first experienced under general anesthesia, is indeed compromised. In contrast, when a mixture of two novel odorants is first experienced under anesthesia and then relearned consciously in pairs with one of the components, the animals show a deficit in relearning only the component but not the mixture. Our results reveal a previously unknown mechanism of unconscious memory due to irreplaceable neuronal commitment under general anesthesia and support the notion that general anesthesia acts at stages beyond cellular coding to disrupt sensory integration for higher-order association.
Asunto(s)
Anestesia General , Aprendizaje , Vías Olfatorias/fisiología , Propofol/farmacología , Animales , Factores de Transcripción con Motivo Hélice-Asa-Hélice Básico/metabolismo , Conducta de Elección/efectos de los fármacos , Cognición/efectos de los fármacos , Estado de Conciencia/efectos de los fármacos , Masculino , Memoria/efectos de los fármacos , Odorantes , Vías Olfatorias/efectos de los fármacos , Corteza Piriforme/efectos de los fármacos , Corteza Piriforme/metabolismo , Ratas Sprague-Dawley , Transcripción Genética/efectos de los fármacosRESUMEN
Volatile general anesthetics continue to be an important part of clinical anesthesia worldwide. The impact of volatile anesthetics on the immune system has been investigated at both mechanistic and clinical levels, but previous studies have returned conflicting findings due to varied protocols, experimental environments, and subject species. While many of these studies have focused on the immunosuppressive effects of volatile anesthetics, compelling evidence also exists for immunoactivation. Depending on the clinical conditions, immunosuppression and activation due to volatile anesthetics can be either detrimental or beneficial. This review provides a balanced perspective on the anesthetic modulation of innate and adaptive immune responses as well as indirect effectors of immunity. Potential mechanisms of immunomodulation by volatile anesthetics are also discussed. A clearer understanding of these issues will pave the way for clinical guidelines that better account for the impact of volatile anesthetics on the immune system, with the ultimate goal of improving perioperative management.
Asunto(s)
Anestésicos por Inhalación/farmacología , Factores Inmunológicos/farmacología , Inmunidad Adaptativa/efectos de los fármacos , Animales , Humanos , Inmunidad Innata/efectos de los fármacosRESUMEN
It is well established that developmental exposure of sevoflurane (an inhalational anesthetic) is capable of inducing neuronal apoptosis and subsequent learning and memory disorders. Synaptic NMDA receptors activity plays an essential role in cell survival, while the extra-synaptic NMDA receptors activation is usually associated with cell death. However, whether synaptic or extra-synaptic NMDA receptors mediate developmental sevoflurane neurotoxicity is largely unknown. Here, we show that developmental sevoflurane treatment decreased NR2A, but increased NR2B subunit expression both in vitro and in vivo. Sevoflurane-induced neuronal apoptosis was attenuated by synaptic NMDA receptors activation or low dose of exogenous NMDA in vitro. Interestingly, these effects could be abolished by NR2A inhibitor PEAQX, but not NR2B inhibitor Ifenprodil in vitro. In contrast, activation of extra-synaptic NMDA receptors alone had no effects on sevoflurane neurotoxicity. In the scenario of extra-synaptic NMDA receptors stimulation, however, sevoflurane-induced neuronal apoptosis could be prevented by addition of Ifenprodil, but not by PEAQX in vitro. In addition, sevoflurane neurotoxicity could also be rescued by memantine, an uncompetitive antagonist for preferential blockade of extra-synaptic NMDA receptors both in vitro and in vivo. Furthermore, we found that developmental sevoflurane-induced phospho-ERK1/2 inhibition was restored by synaptic NMDA receptor activation (in vitro), low dose of NMDA (in vitro) or memantine (in vivo). And the neuroprotective role of synaptic NMDA activity was able to be reversed by MEK1/2 inhibitor U0126 in vitro. Finally, administration of memantine or NMDA significantly improved spatial learning and memory dysfunctions induced by developmental sevoflurane exposure without influence on locomotor activity. These results indicated that activation of synaptic NR2A-containing NMDA receptors, or inhibition of extra-synaptic NR2B-containing NMDA receptors contributed to the relief of sevoflurane neurotoxicity, and the ERK1/2 MAPK signaling may be involved in this process.
Asunto(s)
Antagonistas de Aminoácidos Excitadores/farmacología , Hipocampo/efectos de los fármacos , Sistema de Señalización de MAP Quinasas/efectos de los fármacos , Éteres Metílicos/farmacología , Neuronas/efectos de los fármacos , Receptores de N-Metil-D-Aspartato/metabolismo , Animales , Muerte Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Antagonistas de Aminoácidos Excitadores/metabolismo , Neuronas/metabolismo , Síndromes de Neurotoxicidad/tratamiento farmacológico , Sevoflurano , Transmisión Sináptica/efectos de los fármacos , Transmisión Sináptica/fisiologíaRESUMEN
Aberrant CDK5 activity is implicated in a number of neurodegenerative disorders. Isoflurane exposure leads to neuronal apoptosis, and subsequent learning and memory defects in the developing brain. The present study was designed to examine whether and how CDK5 activity plays a role in developmental isoflurane neurotoxicity. Rat pups and hippocampal neuronal cultures were exposed to 1.5% isoflurane for 4 h. The protein and mRNA levels of CDK5, p35 and p25 were detected by western blot and QReal-Time PCR. CDK5 activity was evaluated in vitro using Histone H1 as a substrate. Roscovitine (an inhibitor of CDK5) was applied before isoflurane treatment, cleaved Caspase-3, Bcl-2, Bax, MEF2 and phospho-MEF2A-Ser-408 expressions were determined. Dominant-Negative CDK5 was transfected before isoflurane treatment. Neuronal apoptosis was evaluated by Flow cytometry (FCM) and TUNEL-staining. Cognitive functions were assessed by Morris water maze. We found that isoflurane treatment led to an aberrant CDK5 activation due to its activator p25 that was cleaved from p35 by calpain. Inhibition of CDK5 activity with Roscovitine enhanced Bcl-2, and decreased cleaved Caspase-3 and Bax expressions. In addition, isoflurane exposure resulted in a decrease of MEF2 and increase of phospho-MEF2A-Ser-408, which were rescued by Roscovitine or Dominant-Negative CDK5 transfection. Dominant-Negative CDK5 transfection also decreased the percentage of TUNEL-positive cells in isoflurane neurotoxicity. Moreover, Roscovitine remarkably alleviated the learning and memory deficits induced by postnatal isoflurane exposure. These results indicated that aberrant CDK5 activity-dependent MEF2 phosphorylation mediates developmental isoflurane neurotoxicity. Inhibition of CDK5 overactivation contributes to the relief of isoflurane neurotoxicity in the developing brain.
Asunto(s)
Quinasa 5 Dependiente de la Ciclina/antagonistas & inhibidores , Hipocampo/efectos de los fármacos , Isoflurano/toxicidad , Neuronas/efectos de los fármacos , Inhibidores de Proteínas Quinasas/farmacología , Purinas/farmacología , Animales , Células Cultivadas , Quinasa 5 Dependiente de la Ciclina/metabolismo , Hipocampo/citología , Hipocampo/metabolismo , Aprendizaje por Laberinto/efectos de los fármacos , Enfermedades Neurodegenerativas/metabolismo , Neuronas/citología , Neuronas/metabolismo , Proteínas Proto-Oncogénicas c-bcl-2/metabolismo , Ratas , Ratas Sprague-Dawley , RoscovitinaRESUMEN
HSV-1, a neurotropic virus, always leads to severe nervous symptoms. It is hard to completely eradicate the latent viruses after conventional therapy so that recurrence is inevitable. ICP is a key regulator for HSV replication and transcription that determines the cytolytic infection or latent state. In search of new anti-virus strategy targeting HSV-1ICP4, two pairs of siRNA were designed, and a recombinant eukaryotic lentiviral expression plasmid pLKO-puro(r)-hU6-siRNA was constructed. Vero cells were transfected with the designed siRNAs by Lipofectamine 2000 and four stable monoclonal cell lines were established by puromycin screening method. The ICP4 expression at mRNA level was detected with real-time PCR, and the HSV-1 replication was measured with TCID50 assay. SiRNA was shown as an effective way to inhibit the expression of ICP4 in monoclonal cell lines. Meanwhile, HSV-1 replication was significantly inhibited when ICP4 was shut down by siRNA. We conclude that siRNA targeting ICP4 attenuates HSV-1 replication. Further more, multi-site siRNAs show stronger inhibitory effect on viral replication, which may be an effective and feasible approach for biological anti-viral drugs.