Effects of repeated exposure to different concentrations of sevoflurane on the neonatal mouse hippocampus / Efeitos da exposição repetida a diferentes concentrações de sevoflurano sobre o hipocampo de ratos neonatos

Abstract Background and objectives: Developing brain is more vulnerable to environmental risk than is the developed brain. We evaluated the effects of repeated exposure to different concentrations of sevoflurane on the neonatal mouse hippocampus using stereological methods. Methods: Eighteen neonatal male mice were randomly divided into three groups. Group A, inhaled sevoflurane at a concentration of 1.5%; Group B, inhaled sevoflurane at a concentration of 3%; and Group C (control group), inhaled only 100% oxygen. Treatments were applied for 30 min a day for 7 consecutive days. The hippocampal volume, dendrite length, number of neurons, and number of glial cells were evaluated in each group using stereological estimations. Results: We identified a ∼2% reduction in the volume of the hippocampus in Group A compared to Group C. Mean hippocampal volume was ∼11% smaller in Group B than it was in Group C. However, these differences in hippocampal volume between the groups were not statistically significant (p > 0.05 for all). As for the number of neurons, we found significantly fewer neurons in Group A (∼29% less) and Group B (∼43% less) than we did in Group C (p < 0.05 for both). The dendrite length was ∼8% shorter in Group A and ∼11% shorter in Group B than it was in Group C. Conclusions: Repeated exposure to sevoflurane, regardless of the concentration, reduced the volume of the neonatal mouse hippocampus, as well as the number of neurons and dendrite length.

Resumo Justificativa e objetivos: O cérebro em desenvolvimento é mais vulnerável ao risco ambiental do que o cérebro já desenvolvido. Avaliamos os efeitos da exposição repetida a diferentes concentrações de sevoflurano sobre o hipocampo de ratos neonatos com o uso de métodos estereológicos. Métodos: Dezoito ratos neonatos foram divididos aleatoriamente em três grupos. O Grupo A foi submetido à inalação de sevoflurano a uma concentração de 1,5%; o Grupo B foi submetido à inalação de sevoflurano a uma concentração de 3%; o Grupo C (controle) foi submetido à inalação de apenas oxigênio a 100%. Os tratamentos foram aplicados durante 30 minutos por dia, durante sete dias consecutivos. Volume do hipocampo, comprimento do dendrito, número de neurônios e número de células gliais foram avaliados em cada grupo com o uso de estimativas estereológicas. Resultados: Identificamos uma redução de ∼2% no volume do hipocampo no Grupo A em comparação com o Grupo C. O volume médio do hipocampo foi ∼11% menor no Grupo B do que no Grupo C. Entretanto, essas diferenças no volume do hipocampo entre os grupos não foram estatisticamente significativas (p > 0,05 para todos). Quanto ao número de neurônios, encontramos um número significativamente menor de neurônios no Grupo A (∼29% menos) e no Grupo B (∼43% menos) do que no Grupo C (p < 0,05 para ambos). O comprimento do dendrito foi ∼8% menor no Grupo A e ∼1% menor no Grupo B que no Grupo C. Conclusões: A exposição repetida ao sevoflurano, independentemente da concentração, reduziu o volume do hipocampo neonatal de camundongos, bem como o número de neurônios e o comprimento dos dendritos.

Novel evaluation of sevoflurane anesthetic exposure on the testicular germ cells of neonatal male mice.

Background: Inhalatory anesthetics may impact spermatogenesis and sexual behavior. Comprehensive evaluation should be conducted to screen the effect of inhalatory anesthetics on the sperm and semen quality. This experimental research was organized to assess the impacts of sevoflurane during the period of neonatal spermatogenesis. Materials and methods: Twenty-one pregnant mice were obtained from the Pasteur Institute. After birth, neonates were categorized based on exposure to Monitored Anesthesia Care (MAC) of sevoflurane into three groups: experimental 1, experimental 2 and control. In order to investigate the testicular condition, a histological evaluation, including apoptosis study and immunohistochemistry, was performed. Not only apoptotic target genes such as Bax and Bcl-2, but also microRNA17-92, were investigated in testicular samples via real-time polymerase chain reaction (real-time PCR). Results: The outcomes of this work indicated the effects of sevoflurane on spermatogonial and germ cells in testicular tissue via stimulating apoptotic target genes and microRNA-17-92. The proportion of Bax/Bcl-2 in the experimental group was 8.318699 ± 1.093, and the proportion of Bax/Bcl-2 in the control group was 2.631 ± 0.079. There was a significant (p ≤ 0.002) difference among the control group and both experimental groups. Conclusion: Sequential sevoflurane exposure during the neonatal period may create testicular dysfunction due to the high level of apoptosis in spermatogonial cells. Also, sevoflurane may affect spermatogenesis by influencing other biomarkers, such as microRNA.

[Effects of repeated exposure to different concentrations of sevoflurane on the neonatal mouse hippocampus]. / Efeitos da exposição repetida a diferentes concentrações de sevoflurano sobre o hipocampo de ratos neonatos.

BACKGROUND AND OBJECTIVES: Developing brain is more vulnerable to environmental risk than is the developed brain. We evaluated the effects of repeated exposure to different concentrations of sevoflurane on the neonatal mouse hippocampus using stereological methods. METHODS: Eighteen neonatal male mice were randomly divided into three groups. Group A, inhaled sevoflurane at a concentration of 1.5%; Group B, inhaled sevoflurane at a concentration of 3%; and Group C (control group), inhaled only 100% oxygen. Treatments were applied for 30min a day for 7 consecutive days. The hippocampal volume, dendrite length, number of neurons, and number of glial cells were evaluated in each group using stereological estimations. RESULTS: We identified a ∼2% reduction in the volume of the hippocampus in Group A compared to Group C. Mean hippocampal volume was ∼11% smaller in Group B than it was in Group C. However, these differences in hippocampal volume between the groups were not statistically significant (p>0.05 for all). As for the number of neurons, we found significantly fewer neurons in Group A (∼29% less) and Group B (∼43% less) than we did in Group C (p<0.05 for both). The dendrite length was ∼8% shorter in Group A and ∼11% shorter in Group B than it was in Group C. CONCLUSIONS: Repeated exposure to sevoflurane, regardless of the concentration, reduced the volume of the neonatal mouse hippocampus, as well as the number of neurons and dendrite length.

Exposure of neonatal mice to Sevoflurane may induce male germ cell apoptosis in testicular tissue after puberty.

BACKGROUND: common use of sevoflurane in congenital defects during repeated surgeries may have detrimental effects on spermatogenesis after puberty. OBJECTIVE: This study investigated sevoflurane effects on spermatogenesis process in male mature mice after exposure in prepubertal time. MATERIALS AND METHODS: 24 neonatal NMRI male mice were randomly classified in three groups. Experimental 1 and 2 groups (exposure to 1 minimum alveolar concentration (MAC) and 2 MAC sevoflurane, respectively in 2 lit/min oxygen (O2) for 7 days (30 min, daily) and control. All groups were sacrificed after 2 months. Histological assessment, immunohistochemistry and apoptosis process was done. Bax and Bcl2 expression was evaluated in the testicular tissue by real time Poly Chain Reaction. RESULTS: Our results showed that the integrity of testicular tissue was preserved in both experimental groups. Count of spermatogonial cells had significant decrease in group 2 compared to others. The rate of apoptosis in spermatogonial cells was 15±3% and 9±2% in the group 2 and 1, respectively. Also, Bax/Bcl2 ratio was 0.2615, 1.0070 and 9.3657 in control, experimental group 1 and 2, respectively. This result was significant (p≤0.002) between groups 2 with other groups. CONCLUSION: Continuous exposure of 2 MAC sevoflurane in 2 lit/min O2 simultaneous during prepubertal may create more testicular tissue damage in terms of cellular and molecular function compared to continuous exposure to lower level of sevoflurane by increase in ratio of Bax/Bcl2 and apoptosis in germ cells after puberty.