Involvement of the caudal raphe nuclei in the feeding behavior of rats

Involvement of the caudal raphe nuclei (raphe pallidus, RPa; raphe magnus, RMg, and raphe obscurus, ROb) in feeding behavior of adult rats was studied by measuring c-Fos protein expression, in animals submitted to the "meal-feeding" model of food restriction in which the rats were fed ad libitum only from 7:00 to 9:00 h, for 15 days. The experimental groups submitted to chronic fasting, named 'search for food' (SF), 'ingestion of food' (IF) and 'satiety of food' (SaF) were scheduled after a previous study in which the body weight and the general and feeding behaviors were evaluated by daily monitoring. Acute, 48-h fasting (AF) was used as control. In the chronic group, the animals presented a 16 percent reduction in body weight in the first week, followed by a continuous, slow rise in weight over the subsequent days. Entrainment of the sleep-wake cycle to the schedule of food presentation was also observed. The RPa was the most Fos immunopositive nucleus in the chronic fasting group, followed by the RMg. The ANOVA and Tukey test (P<0.05) confirmed these results. The IF group was significantly different from the other three groups, as also was the number of labeled cells in the RPa in SF and IF groups. Nevertheless, no significant difference was observed between RMg and RPa, or RMg and ROb in the SaF and AF. However, it is interesting to observe that the groups in which the animals were more active, searching for or ingesting food, presented a larger number of labeled cells. These results suggest a different involvement of the caudal raphe nuclei in the somatic and autonomic events of feeding behavior, corroborating the functions reported for them earlier

Expressäo de prolactina, c-fos e TGFßno endométrio humano: influência do ciclo menstrual e efeitos de acetato de medroxiprogesterona / Expression of prolactin, c-fos and TGFß in human endometrium: influence of the mestrual cycle and medroxyprogesterone acetate effects

O mecanismo de açao dos esteróides sexuais sobre a proliferaçao e deferenciaçao do endométrio envolve a paraticipaçao de fatores de crescimento e protooncogenes, cuja regulaçao é pouco conhecida. O objetivo deste trabalho foi investigar a influência do ciclo menstrual e os efeitos do acetado de medroxiprogesterona (MPA) sobre a expressao de prolactina (PRL), do protooncogene c-fos e do fator de crescimento TGFBeta no endométrio humano in vivo. Quarenta e seis mulheres com ciclos regulares receberam, de forma randomizada, placebo ou MPA (10mg/dia, 10 dias). Em seguida foram submetidas a biópsia do endométrio e as amostras foram classificadas em 3 grupos de acordo com a fase do ciclo/tratamento: Proliferativo/Placebo (grupo 1, N=11), Secretor/Placebo (grupo 2, N=18) e o Secretor/MPA (grupo 3, N=8). Parte do material foi fixada em formol e incluída em parafina, sendo posteriormente submetida a coloraçao por imuno-histoquímica. O restante foi congelado a-70 Graus Celsius para posterior análise do RNA mensageiro (mRNA) pela técnica de RT-PCR. Encoutrou-se PRL imunorreativa no epitélio glandular de 9,1 por cento das amostras do grupo 1, em 55,6 por cento das amostras do grupo 2 e em 100 por cento das amostras do grupo 3 (p<0,05; teste de Fisher). No estroma endometrial, observou-se imunocoloraçao para PRL em 9,1 por cento, 66,7 por cento e 87,5 por cento das biópsias dos grupos 1,2 e 3, respectivamente (p<0,01). Os níveis médio de mRNA da PRL foram maiores na fase secretora (grupo 2) e significativamente maiores no grupo 3 em relaçao ao grupo 1 (p<0,05). Observou-se imunocoloraçao para c-fos (predominando no núcleo das células estromais) em 54,5 por cento das biópsias do grupo 1, em 7,1 por cento das do grupo 2 e em nenhuma do grupo 3 (p<0,05, grupo 1 vs 2 e 3). Os níveis de mRNA do c-fos foram substancialmente menores nos grupos 2 e 3 comparados ao grupo 1 (p<0,05) e apresentaram correlaçao direta com os níveis séricos de estradiol (r=0,56; p<0,02). Nao houve diferença entre os grupos quanto à expressao de TGFBeta 1. Entretanto, a freqüência de amostras com imunocolaraçao positiva para TGFBeta 3 foram sucessivamente maiores nos grupos 2 e 3 em comparaçao com o grupo 1. Os dados demonstram aumento da expressao de PRL e TGFBeta 3 e inibiçao da expressao de c-fos no endométrio durante a fase secretora do ciclo menstrual, bem como no endométrio estimulado por MPA. A inibiçao de c-fos e o aumento na expressao de TGFBeta 3 poderiam...

Analise da expressao dos proto-oncogenes fos e jun: formacao de complexo AP-1 e implicacoes biologicas / Analysis of expression of the proto-oncogene fos and jun: formation of complex AP-1 e biological implications

Para investigar o papel biologico dos proto-oncogenes fos (c-fos,fosB, fra-1 e fra-2) e jun (c-jun, junB e junD), nos propusemos a analisar a expressao dos membros destas duas familias genicas durante a organogenese de camundongos e promover a expressao heterologa de cFos e cJun utilizando o sistema de baculovirus em celulas Sf9 de inseto. A analise da expressao tecido-especifica dos genes fos e jun, por hibridizacao in situ, mostrou um padrao diferencial de expressao destes genes e embrioes de camundongos. A localizacao, ao nivel celular, dos transcritos correspondentes indica que diferentes complexos AP-1 podem desempenhar um papel especifico na organogenese. As proteinas cFos e cJun recombinantes produzidas em sistema de baculovirus apresentaram varias das caracteristicas das proteinas nativas como peso molecular esperado, fosfolrilacao, localizacao nuclear e capacidade de complexos AP-1 biologicamente ativos

Stress-induced expression of the c-fos proto-oncogene in the hippocampal formation

To investigate the effects of stress on c-fos mRNA expression, rats were submitted to forced immobilization for 15, 30, 60 or 120 min before sacrifice. In situ hybridization was performed on sections containing the dorsal hippocampus with a 32P-labelled 50-base oligonucleotide probe (10(7)-10(9) cpm/micrograms) complementary to nucleotides 370-319 of rat c-fos. Forced restraint induced a time-dependent increase in c-fos mRNA expression which was most pronounced in the dentate gyrus and CA1-CA3 regions of the hippocampal formation, and which peaked after 30 min of immobilization (72.7 +/- 1.0 vs 24.1 +/- 0.8 cpm/mm2 in unrestrained animals). A positive but weaker signal was also detected in the amygdala, pyriform cortex and other parts of the cerebral cortex and habenulae. These results suggest that the hippocampal formation is activated during stress.

Regional distribution of Fos-like immunoreactivity in the rat brain after exposure to fear-inducing stimuli

Fos protein immunohistochemistry was used to identify the neural substrate of fear/anxiety. The structures activated by exposure of Long Evans male rats (280-300 g) to the elevated plus-maze, a widely used animal model of anxiety, were compared with those activated by chemical stimulation of two aversive areas of the brain, the dorsal periaqueductal gray matter and the medial hypothalamus. Three different patterns of activation were obtained: Pattern 1 resulted from microinjection of the excitatory amino acid kainate (60 pmol; N = 5) or of the GABA(A) receptor antagonist SR-95531 (16 pmol; N = 3) into the dorsal periaqueductal gray matter and consisted mainly of caudal structures; Pattern 2 was observed after kainate injection (60 pmol; N = 4) into the medial hypothalamus and had a predominantly prosencephalic distribution; Pattern 3 extended from rostral to caudal brain regions and was induced by microinjection of either SR-95531 (16 pmol; N = 1) or kainate (120 pmol; N = 3) into the medial hypothalamus, as well as by 15-min exposure to the plus-maze (N = 3). Control animals were either injected with saline into the MH (N = 3) or the PAG (N = 3) or were exposed for 15 s to the elevated plus maze (N = 3) and exhibited no significant labeling. These results further support the participation of periventricular structures in the regulation of fear and aversion.