Isoflurane provides neuroprotection in neonatal hypoxic ischemic brain injury by suppressing apoptosis / Isoflurano fornece neuroproteção em lesão cerebral hipóxico-isquêmica neonatal por inibição da apoptose

Abstract Background and objectives: Isoflurane is halogenated volatile ether used for inhalational anesthesia. It is widely used in clinics as an inhalational anesthetic. Neonatal hypoxic ischemia injury ensues in the immature brain that results in delayed cell death via excitotoxicity and oxidative stress. Isoflurane has shown neuroprotective properties that make a beneficial basis of using isoflurane in both cell culture and animal models, including various models of brain injury. We aimed to determine the neuroprotective effect of isoflurane on hypoxic brain injury and elucidated the underlying mechanism. Methods: A hippocampal slice, in artificial cerebrospinal fluid with glucose and oxygen deprivation, was used as an in vitro model for brain hypoxia. The orthodromic population spike and hypoxic injury potential were recorded in the CA1 and CA3 regions. Amino acid neurotransmitters concentration in perfusion solution of hippocampal slices was measured. Results: Isoflurane treatment caused delayed elimination of population spike and improved the recovery of population spike; decreased frequency of hypoxic injury potential, postponed the onset of hypoxic injury potential and increased the duration of hypoxic injury potential. Isoflurane treatment also decreased the hypoxia-induced release of amino acid neurotransmitters such as aspartate, glutamate and glycine induced by hypoxia, but the levels of γ-aminobutyric acid were elevated. Morphological studies showed that isoflurane treatment attenuated edema of pyramid neurons in the CA1 region. It also reduced apoptosis as evident by lowered expression of caspase-3 and PARP genes. Conclusions: Isoflurane showed a neuro-protective effect on hippocampal neuron injury induced by hypoxia through suppression of apoptosis.

Resumo Justificativa e objetivos: Isoflurano é um éter volátil halogenado usado para anestesia por via inalatória. É amplamente usado na clínica como um anestésico para inalação. A lesão hipóxico-isquêmica neonatal ocorre no cérebro imaturo e resulta em morte celular tardia via excitotoxicidade e estresse oxidativo. Isoflurano mostrou ter propriedades neuroprotetoras que formam uma base benéfica para o seu uso tanto em cultura de células quanto em modelos animais, incluindo vários modelos de lesão cerebral. Nosso objetivo foi determinar o efeito neuroprotetor de isoflurano em hipóxia cerebral e elucidar o mecanismo subjacente. Métodos: Fatias de hipocampo, em fluido cerebrospinal artificial (CSFA) com glicose e privação de oxigênio, foram usadas como um modelo in vitro de hipóxia cerebral. O pico de população ortodrômica (PPO) e o potencial de lesão hipóxica (PLH) foram registrados nas regiões CA1 e CA3. A concentração de neurotransmissores de aminoácidos na solução de perfusão das fatias de hipocampo foi medida. Resultados: O tratamento com isoflurano retardou a eliminação do PPO e melhorou a recuperação do PPO; diminuiu a frequência do PLH, retardou o início do PLH e aumentou a duração do PLH. O tratamento com isoflurano também diminuiu a liberação de neurotransmissores de aminoácidos induzida pela hipóxia, como aspartato, glutamato e glicina, mas os níveis de ácido γ-aminobutírico (GABA) estavam elevados. Estudos morfológicos mostram que o tratamento de edema com isoflurano atenuou o edema de neurônios piramidais na região CA1. Também reduziu a apoptose, como mostrado pela expressão reduzida da caspase-3 e genes PARP. Conclusões: Isoflurano mostrou um efeito neuroprotetor na lesão neuronal no hipocampo induzida por hipóxia através da supressão de apoptose.

[Effect of gestational diabetes on astrocyte density in CA1 and CA3 subfields of hippocampus in rat offspring]

Diabetes mellitus is one of the most common serious metabolic disorders characterized by hyperglycemia, altered metabolism of lipids, carbohydrates and proteins. Gestational diabetes mellitus [GDM], affects 3.5-5% of all human pregnancy. Therefore, this study was done to evaluate the effect of gestational diabetes on astrocyte density in CA1 and CA3 subfields of hippocampus in rat male offspring. In this experimental study, 12 Wistar Dams rats were randomly allocated in control and diabetic groups. Gestational diabetes induced by 40 mg/kg/body weight of streptozotocin at the first day of gestation [GD] in experimental group and controls were received an equivalent volume normal saline injection intraperitoneally [IP]. Six male offspring of cases and controls dams, at the 7, 21 postnatal day [P7, P21] were randomly selected. Animals were scarified using chloroform anesthesia. The coronal sections of brain by 6 micrometer serially were prepared. The sections were stained with PTAH. The number of astrocytes was evaluated in 100000 micro m[2] area of CA1 and CA3 in 1000X magnification. Data was analyzed by SPSS-11.5 and t-test. In CA1 subfield of hippocampus in offspring, the number of astrocytes significantly reduced by 36.25% and 36.37% in diabetic group in compare to controls in the P7 and P21, respectively [P<0.05]. In CA3, astrocytes density significantly reduced 36.35% and 26.5% in GD in comparison with controls in the P7 and P21, respectively [P<0.05]. This study showed that the uncontrol gestational diabetes significantly reduces astrocytes density in CA1 and CA3 subfields of hippocampus in rat offspring