RESUMO
The pancreatic peptide hormone amylin (AMY) and the AMY receptor agonist salmon calcitonin (sCT) reduce short-term food intake in rats primarily by activating neurons located in the circumventricular area postrema. In the present study we analyzed the involvement of (an)orexigenic neuropeptides expressed in the lateral hypothalamic area (LHA) and in the arcuate nucleus in mediating the AMY and sCT-induced suppression of food intake. By using semiquantitative in situ hybridization 120 min after intraperitoneal injection of AMY or sCT (50 microgram/kg), orexin mRNA levels were decreased in LHA by AMY or sCT treatment. Moreover, sCT significantly suppressed the orexigenic melanin concentrating hormone in LHA, whereas mRNA levels of neuropeptide Y, cocaine and amphetamine regulated transcript, agouti-gene-related protein and proopiomelanocortin were unaffected by either treatment. In conclusion, the anorexigenic effect of AMY/sCT might be mediated by the observed reduced expression of orexigenic neuropeptides in the LHA.
Assuntos
Amiloide/farmacologia , Núcleo Arqueado do Hipotálamo/efeitos dos fármacos , Calcitonina/farmacologia , Regulação da Expressão Gênica/efeitos dos fármacos , Região Hipotalâmica Lateral/efeitos dos fármacos , Peptídeos e Proteínas de Sinalização Intracelular , Neuropeptídeos/genética , Proteína Relacionada com Agouti , Animais , Antiulcerosos/farmacologia , Núcleo Arqueado do Hipotálamo/metabolismo , Autorradiografia/métodos , Proteínas de Transporte/genética , Ingestão de Alimentos/efeitos dos fármacos , Região Hipotalâmica Lateral/metabolismo , Hormônios Hipotalâmicos/genética , Hibridização In Situ/métodos , Peptídeos e Proteínas de Sinalização Intercelular , Polipeptídeo Amiloide das Ilhotas Pancreáticas , Masculino , Melaninas/genética , Proteínas do Tecido Nervoso/metabolismo , Neuropeptídeo Y/genética , Neuropeptídeos/metabolismo , Sondas de Oligonucleotídeos , Receptores de Orexina , Orexinas , Fragmentos de Peptídeos/farmacologia , Hormônios Hipofisários/genética , Pró-Opiomelanocortina/genética , Proteínas/genética , RNA Mensageiro/biossíntese , Ratos , Ratos Wistar , Receptores Acoplados a Proteínas G , Receptores de Neuropeptídeos , Receptores de Hormônios Pancreáticos/antagonistas & inibidores , SalmãoRESUMO
The effects of the 17beta-estradiol, dihydrotestosterone and hormone antagonists tamoxifen and bicalutamide on telomerase activity and expression of cell cycle related proteins in the androgen-sensitive prostatic cancer cell line LNCaP were studied. The cell line was grown in RPMI supplemented with 2.5% charcoal-stripped FBS for 72 hr. The IC(50) of tamoxifen and bicalutamide and the optimal stimulatory concentrations of 17beta-estradiol and dihydrotestosterone were determined by means of the cell-viability assay, the activity of telomerase was measured by the telomere repeat amplification protocol (TRAP) and the expression of proteins was analysed by the Western blot technique. 17beta-estradiol stimulated cell growth more effectively than dihydrotestosterone whereas hormone antagonists tamoxifen and bicalutamide caused a significant decrease in cell viability. The treatment of cells by a combination of low doses of 17 beta-estradiol and dihydrotestosterone stimulated cells stronger than treatment by a single hormone. Only 17beta-estradiol, in concentration of 10nM, increased strongly the expression of p21(Waf1/Cip1) and increased slightly telomerase activity in the LNCaP cells. 50 microM of bicalutamide down-regulated the levels of the androgen receptor, the proliferating cell nuclear antigen and telomerase activity, and up-regulated the expression of p27(Kip1). We hereby describe the first observation of the influence of bicalutamide on telomerase activity and a positive correlation between the effect of 17beta-estradiol and the induction of both the endogenous cyclin-dependent kinase inhibitor, p21(Waf1/Cip1), and telomerase activity in a prostatic cancer cell line LNCaP. These findings can shed a new light on the steroid-signaling pathway in prostate cancer cells.
