RESUMO
Drug metabolism could be altered in patients with chronic renal failure (CRF). In rats, this phenomenon is related to a decrease in liver cytochrome P450 (P450) and phase II enzymes, particularly N-acetyltransferase 2 (NAT2). This study attempted to determine the effects of CRF on liver P450 isoforms and NAT2 expressions by using a CRF mouse model. Two groups of mice were studied: CRF induced by 3/4 nephrectomy and control. Liver protein expression and mRNA levels of the major P450 isoforms involved in drug metabolism (CYP1A2, 2C29, 2D, 2E1, and 3A11) and NAT2 were measured by Western blot and real-time polymerase chain reaction (PCR), respectively. CYP3A activity was also assessed by the N-demethylation of erythromycin. Results showed a significant reduction in the protein expression of CYP1A2 (56%), 2C29 (31%), and 3A11 (37%) in CRF mice compared with control animals. Real-time PCR revealed a similar reduction in mRNA levels of CYP1A2, 2C29, and 3A11 (59, 56, and 37%, respectively), in CRF mice. There was no significant modification in protein expression and mRNA of CYP2D and 2E1. Compared with control animals, CRF mice displayed a 25% reduction in N-demethylation of erythromycin. For NAT2, protein expression decreased by 33% and mRNA levels decreased by 23%. In conclusion, this study demonstrates that protein expression of liver CYP1A2, CYP2C29, and CYP3A11 is down-regulated in CRF mice, secondary to reduced gene expression. Phase II enzymes are similarly affected by CRF. Our results will allow the use of knockout mice to determine the mechanism underlying CRF-induced down-regulation of liver drug-metabolizing enzymes.
Assuntos
Biotransformação , Sistema Enzimático do Citocromo P-450/metabolismo , Regulação para Baixo , Falência Renal Crônica/metabolismo , Fígado/enzimologia , Animais , Arilamina N-Acetiltransferase/genética , Arilamina N-Acetiltransferase/metabolismo , Creatinina/sangue , Citocromo P-450 CYP1A2/genética , Citocromo P-450 CYP1A2/metabolismo , Citocromo P-450 CYP3A/genética , Citocromo P-450 CYP3A/metabolismo , Sistema Enzimático do Citocromo P-450/genética , Modelos Animais de Doenças , Eritromicina/metabolismo , Regulação Enzimológica da Expressão Gênica , Isoenzimas/genética , Isoenzimas/metabolismo , Falência Renal Crônica/sangue , Falência Renal Crônica/genética , Fígado/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Nefrectomia , RNA Mensageiro/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Ureia/sangueRESUMO
Cytochrome P450 (CYP) functional expression is reduced in uremia and normalized after restoration of kidney function via transplantation. The aim of this study was to evaluate the effect of conventional hemodialysis on the functional expression of CYP1A, 2C, and 3A. We also investigated the role of nuclear factor-kappaB (NF-kappaB) in CYP regulation during uremia. Primary cultures of normal rat hepatocytes were incubated with serum obtained from end-stage renal disease patients pre- and post-hemodialysis and healthy control subjects, in the presence and absence of the NF-kappaB inhibitor andrographolide. Uremic pre-hemodialysis serum caused significant reductions (P<0.01) in CYP1A (44%), 2C (27%), and 3A (35%) protein expression compared to control serum, while dialyzed serum (i.e., obtained immediately post-hemodialysis) had no effect. CYP1A2, 2C11, and 3A2 mRNA expression, as well as CYP3A activity, were similarly impacted by uremic serum and were improved to >80% of control values after hemodialysis. NF-kappaB inhibition nearly eliminated the effect of uremic serum on CYP functional expression. This is the first study to demonstrate that conventional hemodialysis acutely improves altered CYP functional expression observed in rat hepatocytes incubated with uremic human serum.
Assuntos
Sistema Enzimático do Citocromo P-450/metabolismo , Hepatócitos/enzimologia , Falência Renal Crônica/terapia , Fígado/enzimologia , Diálise Renal , Uremia/terapia , Idoso , Idoso de 80 Anos ou mais , Animais , Hidrocarboneto de Aril Hidroxilases/metabolismo , Células Cultivadas , Citocromo P-450 CYP1A2/metabolismo , Citocromo P-450 CYP3A , Sistema Enzimático do Citocromo P-450/genética , Família 2 do Citocromo P450 , Citocromos , Diterpenos/farmacologia , Regulação para Baixo , Feminino , Regulação Enzimológica da Expressão Gênica , Hepatócitos/efeitos dos fármacos , Humanos , Falência Renal Crônica/sangue , Fígado/efeitos dos fármacos , Masculino , Proteínas de Membrana/metabolismo , Pessoa de Meia-Idade , NF-kappa B/antagonistas & inibidores , NF-kappa B/metabolismo , RNA Mensageiro/metabolismo , Ratos , Ratos Sprague-Dawley , Esteroide 16-alfa-Hidroxilase/metabolismo , Uremia/sangueRESUMO
Paracetamol analgesic mechanism of action is still poorly defined but mainly involves central inhibition of cyclooxygenases. Here we tested the peripheral antinociceptive effects of paracetamol (intraplantar injections) in a rat model of neuropathic pain. Paracetamol dose-dependently decreased mechanical allodynia and lowered nociceptive scores associated with hyperalgesia testing. These effects were inhibited by the administration of cannabinoid CB(1) (AM251) and CB(2) (AM630) receptor antagonists. The participation of the peripheral cannabinoid system in paracetamol analgesia is suggested.
Assuntos
Acetaminofen/farmacologia , Analgésicos não Narcóticos/farmacologia , Neuralgia/prevenção & controle , Receptores de Canabinoides/fisiologia , Animais , Ácidos Araquidônicos/metabolismo , Antagonistas de Receptores de Canabinoides , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Membro Posterior/inervação , Temperatura Alta/efeitos adversos , Hiperalgesia/etiologia , Hiperalgesia/fisiopatologia , Hiperalgesia/prevenção & controle , Indóis/farmacologia , Masculino , Neuralgia/etiologia , Neuralgia/fisiopatologia , Medição da Dor/métodos , Piperidinas/farmacologia , Pirazóis/farmacologia , Ratos , Ratos Wistar , Receptor CB1 de Canabinoide/antagonistas & inibidores , Receptor CB1 de Canabinoide/fisiologia , Receptor CB2 de Canabinoide/antagonistas & inibidores , Receptor CB2 de Canabinoide/fisiologia , Nervo Isquiático/lesõesRESUMO
The antinociceptive effects of WIN55,212-2, a synthetic cannabinoid, were evaluated in the model of partial sciatic nerve ligation after daily subcutaneous administration of 0.1 mg/kg a week before and two weeks after surgery. Mechanical allodynia and thermal hyperalgesia were evaluated in 46 rats allocated to receive: (1) Vehicle (before surgery)-Vehicle (after surgery); (2) Vehicle-WIN55,212-2; (3) WIN55,212-2-Vehicle; (4) WIN55,212-2-WIN55,212-2; (5) AM251+vehicle; (6) AM251+WIN55,212-2; (7) AM630+vehicle; (8) AM630+WIN55,212-2; (9) Sham receiving vehicle; and (10) Sham receiving WIN55,212-2. The decreased in mechanical allodynia and thermal hyperalgesia by WIN55,212-2 was significantly greater when it was administered during one week before surgery. In conclusion, pre-emptive use of cannabinoids produced greater antinociceptive effects in a model of neuropathic pain and this effect is mediated by cannabinoid CB(1) and CB(2) receptors.
