Conspecific odor exposure predominantly activates non-kisspeptin cells in the medial nucleus of the amygdala.

A small neuronal subpopulation in the medial nucleus of the amygdala (MeA), expressing the Kiss1 gene, is now considered an important mediator that integrates socio-sexual behavior and odor information in order to modulate the Hypothalamic-Pituitary-Gonadal (HPG) axis. Previous studies demonstrated that exogenous kisspeptin administration or selective activation of Kiss1-expressing neurons in the MeA modulates the onset of puberty, LH secretion and sexual behavior. These functions are supported by the known MeA neuronal connections. In the MeA, as well as in the hypothalamus, Kiss1 mRNA expression mostly depends on sex steroids levels. However, the percentage of Kiss1-expressing cells that co-express estrogen receptor α (ERα) in the MeA is currently unknown. Additionally, whether MeA kisspeptin neurons show Fos expression due to pheromone exposure is still undisclosed. In the present study, we used adult male and female mice that express a reporter protein under the Kiss1 promoters to determine the percentage of Kiss1-expressing neurons that co-express the ERα in the MeA and, whether those cells are activated by olfactory cues. We found a high percentage of Kiss1-expressing neurons in the MeA co-expressing the ERα. The proportion of co-expression was similar between male and female mice in diestrus. Interestingly, a low percentage of Kiss1-expressing neurons in the MeA co-express Fos after conspecific odor exposure, despite a significant increase of Fos positive cells in the MeA. Additionally, odor exposition leads to a sexually dimorphic change in Kiss1 expression in the posterior subdivision of the MeA. Our findings suggest that olfactory signals predominantly activate non-kisspeptin cells in the MeA to modulate responses to pheromones and therefore the HPG axis.

Clinical and histological responses to laparoscopically-induced peritonitis in rats / Resposta clínica e histológica à indução de peritonite via laparoscopia em ratos

PURPOSE: To evaluate the efficacy of inducing peritonitis in rats through laparoscopic cecal ligation (CL), by means of an elastic band. METHODS: Twelve Wistar rats were subjected to cecal ligated with an elastic band applied using a specially constructed applicator. In six of the animals (the CL group) the cecal sac was preserved intact whilst in the remaining animals (the CLP group) the sac was perforated with scissors. Clinical parameters, characteristics of the peritoneal cavity and cecum, and histological features of the cecal tissue were observed in all experimental animals 8 and 24 h after surgery. RESULTS: CLP animals exhibited at least one clinical sign of sepsis within the first 8 h of observation. The peritoneal liquid was observed to be clear in almost all members of the CLP. Polymorphonucleated cells were detected in the tunica serosa of the cecum of CLP animals. In contrast, all members of the CL group were alive after 24h, and of polymorphonucleated cells in the muscle layer of the cecal wall were observed. The presence of peritoneal liquid was not detected in CL animals. CONCLUSION: Although elastic ligation of the cecum was reproducible, puncture of the cecal sac was essential for induction of sepsis.

OBJETIVO: Avaliar a eficácia de induzir peritonite em ratos através da ligadura cecal laparoscópica (CL), por meio de banda elástica. MÉTODOS: Doze ratos Wistar foram submetidos a ligadura cecal com banda elástica aplicada com dispositivo especialmente construído para este fim. Em seis animais (grupo CL), a bolsa cecal foi mantida intacta, enquanto nos outros animais (grupo CLP), a bolsa foi perfurada com tesoura. Parâmetros clínicos, características da cavidade peritonial e ceco, e histologia do tecido cecal foram examinados em todos os animais 8 e 24 horas após a cirurgia. RESULTADOS: Os animais do grupo CLP apresentaram pelo menos um sinal clínico de sepses nas primeiras 8 h de observação. Líquido peritonial claro foi observado em quase todos os membros do grupo CLP. Leucócitos polimorfonucleares foram identificados na serosa do ceco dos animais do grupo CLP. Por outro lado, todos os animais do grupo CL estavam vivos após 24 h, e leucócitos polimorfonucleares estavam restritos à muscular própria. Presença de líquido peritonial não foi detectada nos animais do grupo CL. CONCLUSÃO: A ligadura elástica do ceco foi reprodutível e a secção da bolsa cecal foi essencial para a indução de sepse.

Clinical and histological responses to laparoscopically-induced peritonitis in rats / Resposta clínica e histológica à indução de peritonite via laparoscopia em ratos

PURPOSE: To evaluate the efficacy of inducing peritonitis in rats through laparoscopic cecal ligation (CL), by means of an elastic band. METHODS: Twelve Wistar rats were subjected to cecal ligated with an elastic band applied using a specially constructed applicator. In six of the animals (the CL group) the cecal sac was preserved intact whilst in the remaining animals (the CLP group) the sac was perforated with scissors. Clinical parameters, characteristics of the peritoneal cavity and cecum, and histological features of the cecal tissue were observed in all experimental animals 8 and 24 h after surgery. RESULTS: CLP animals exhibited at least one clinical sign of sepsis within the first 8 h of observation. The peritoneal liquid was observed to be clear in almost all members of the CLP. Polymorphonucleated cells were detected in the tunica serosa of the cecum of CLP animals. In contrast, all members of the CL group were alive after 24h, and of polymorphonucleated cells in the muscle layer of the cecal wall were observed. The presence of peritoneal liquid was not detected in CL animals. CONCLUSION: Although elastic ligation of the cecum was reproducible, puncture of the cecal sac was essential for induction of sepsis.(AU)

OBJETIVO: Avaliar a eficácia de induzir peritonite em ratos através da ligadura cecal laparoscópica (CL), por meio de banda elástica. MÉTODOS: Doze ratos Wistar foram submetidos a ligadura cecal com banda elástica aplicada com dispositivo especialmente construído para este fim. Em seis animais (grupo CL), a bolsa cecal foi mantida intacta, enquanto nos outros animais (grupo CLP), a bolsa foi perfurada com tesoura. Parâmetros clínicos, características da cavidade peritonial e ceco, e histologia do tecido cecal foram examinados em todos os animais 8 e 24 horas após a cirurgia. RESULTADOS: Os animais do grupo CLP apresentaram pelo menos um sinal clínico de sepses nas primeiras 8 h de observação. Líquido peritonial claro foi observado em quase todos os membros do grupo CLP. Leucócitos polimorfonucleares foram identificados na serosa do ceco dos animais do grupo CLP. Por outro lado, todos os animais do grupo CL estavam vivos após 24 h, e leucócitos polimorfonucleares estavam restritos à muscular própria. Presença de líquido peritonial não foi detectada nos animais do grupo CL. CONCLUSÃO: A ligadura elástica do ceco foi reprodutível e a secção da bolsa cecal foi essencial para a indução de sepse.(AU)

Clinical and histological responses to laparoscopically-induced peritonitis in rats.

PURPOSE: To evaluate the efficacy of inducing peritonitis in rats through laparoscopic cecal ligation (CL), by means of an elastic band. METHODS: Twelve Wistar rats were subjected to cecal ligated with an elastic band applied using a specially constructed applicator. In six of the animals (the CL group) the cecal sac was preserved intact whilst in the remaining animals (the CLP group) the sac was perforated with scissors. Clinical parameters, characteristics of the peritoneal cavity and cecum, and histological features of the cecal tissue were observed in all experimental animals 8 and 24 h after surgery. RESULTS: CLP animals exhibited at least one clinical sign of sepsis within the first 8 h of observation. The peritoneal liquid was observed to be clear in almost all members of the CLP. Polymorphonucleated cells were detected in the tunica serosa of the cecum of CLP animals. In contrast, all members of the CL group were alive after 24h, and of polymorphonucleated cells in the muscle layer of the cecal wall were observed. The presence of peritoneal liquid was not detected in CL animals. CONCLUSION: Although elastic ligation of the cecum was reproducible, puncture of the cecal sac was essential for induction of sepsis.