RESUMO
Moderate exercise reduces arterial pressure (AP) and heart rate (HR) in spontaneously hypertensive rats (SHR) and changes neurotransmission in medullary areas involved in cardiovascular regulation. We investigated if regularly swimming exercise (SW) affects the cardiovascular adjustments mediated by opioidergic neuromodulation in the RVLM in SHR and Wistar-Kyoto (WKY) rats. Rats were submitted to 6 wks of SW. The day after the last exercise bout, α-chloralose-anesthetized rats underwent a cannulation of the femoral artery for AP and HR recordings, and Doppler flow probes were placed around the lower abdominal aorta and superior mesenteric artery. Bilateral injection of endomorphin-2 (EM-2, 0.4 mmol/L, 60 nL) into the RVLM increased MAP in SW-SHR (20 ± 4 mmHg, N = 6), which was lower than in sedentary (SED)-SHR (35 ± 4 mmHg, N = 6). The increase in MAP in SW-SHR induced by EM-2 into the RVLM was similar in SED- and SW-WKY. Naloxone (0.5 mmol/L, 60 nL) injected into the RVLM evoked an enhanced hypotension in SW-SHR (-66 ± 8 mmHg, N = 6) compared to SED-SHR (-25 ± 3 mmHg, N = 6), which was similar in SED- and SW-WKY. No significant changes were observed in HR after EM-2 or naloxone injections into the RVLM. Changes in hindquarter and mesenteric conductances evoked by EM-2 or naloxone injections into the RVLM in SW- or SED-SHR were not different. Mu Opioid Receptor expression by Western blotting was reduced in SW-SHR than in SED-SHR and SW-WKY. Therefore, regularly SW alters the opioidergic neuromodulation in the RVLM in SHR and modifies the mu opioid receptor expression in this medullary area.
Assuntos
Analgésicos Opioides/farmacologia , Hipertensão/metabolismo , Bulbo/metabolismo , Neurônios/efeitos dos fármacos , Condicionamento Físico Animal , Receptores Opioides mu/metabolismo , Animais , Pressão Arterial/efeitos dos fármacos , Pressão Arterial/fisiologia , Frequência Cardíaca/efeitos dos fármacos , Frequência Cardíaca/fisiologia , Bulbo/efeitos dos fármacos , Naloxona/farmacologia , Antagonistas de Entorpecentes/farmacologia , Neurônios/metabolismo , Oligopeptídeos/farmacologia , Ratos , Ratos Endogâmicos SHR , Ratos Endogâmicos WKY , NataçãoRESUMO
Measuring thyroid hormones is an important aspect for the study of metabolism and for monitoring diseases in both human and animal models. The traditional method for hormone measurement in rats is the radioimmunoassay (RIA). However, the RIA is associated with some practical disadvantages, including the use of radioactive material, the need for specialized equipment and expert staff, the short shelf-life of kits according to the half-life of the radioisotope and high costs. The objective of this study was to develop a new cost-effective method for measuring TSH levels in rats that avoids the use of radioactive material. We developed an in-house competitive immunoassay using a reference standard, polyclonal antibody produced in rabbits and biotinylated antigen. This method was tested in 64 Wistar rats that were divided into a control group (n = 41) and a group with hypothyroidism (n = 23). Our assay demonstrated an analytical sensitivity of 0.24 ng/mL (n = 12) and an intra-assay coefficient of variation (CV) of 8.9% for sera with TSH levels of 1.5 ng/mL and 13.2% for sera with TSH levels of 17.5 ng/mL (n = 14). The inter-assay CV was 13.5% for sera with TSH levels of 1.4 ng/mL and 14.5% for TSH levels of 18.2 ng/mL (n = 5). The analysis of mean TSH levels in control rats (5.06 ± 0.5701) and hypothyroid rats (51.09 ± 5.136) revealed a statistically significant difference (p < 0.001) between the groups. This method showed good sensitivity, can be automated and is low-cost compared with RIA. Our method offers a viable alternative for TSH measurement in rats.
Assuntos
Imunoensaio/métodos , Doenças da Glândula Tireoide/diagnóstico , Tireotropina/sangue , Animais , Análise Custo-Benefício , Imunoensaio/economia , Masculino , Coelhos , Ratos , Ratos Wistar , Sensibilidade e Especificidade , Doenças da Glândula Tireoide/sangueRESUMO
Millions of levothyroxine-treated hypothyroid patients complain of impaired cognition despite normal TSH serum levels. This could reflect abnormalities in the type 2 deiodinase (D2)-mediated T4-to-T3 conversion, given their much greater dependence on the D2 pathway for T3 production. T3 normally reaches the brain directly from the circulation or is produced locally by D2 in astrocytes. Here we report that mice with astrocyte-specific Dio2 inactivation (Astro-D2KO) have normal serum T3 but exhibit anxiety-depression-like behavior as found in open field and elevated plus maze studies and when tested for depression using the tail-suspension and the forced-swimming tests. Remarkably, 4 weeks of daily treadmill exercise sessions eliminated this phenotype. Microarray gene expression profiling of the Astro-D2KO hippocampi identified an enrichment of three gene sets related to inflammation and impoverishment of three gene sets related to mitochondrial function and response to oxidative stress. Despite normal neurogenesis, the Astro-D2KO hippocampi exhibited decreased expression of four of six known to be positively regulated genes by T3, ie, Mbp (â¼43%), Mag (â¼34%), Hr (â¼49%), and Aldh1a1 (â¼61%) and increased expression of 3 of 12 genes negatively regulated by T3, ie, Dgkg (â¼17%), Syce2 (â¼26%), and Col6a1 (â¼3-fold) by quantitative real-time PCR. Notably, in Astro-D2KO animals, there was also a reduction in mRNA levels of genes known to be affected in classical animal models of depression, ie, Bdnf (â¼18%), Ntf3 (â¼43%), Nmdar (â¼26%), and GR (â¼20%), which were also normalized by daily exercise sessions. These findings suggest that defects in Dio2 expression in the brain could result in mood and behavioral disorders.
Assuntos
Ansiedade/enzimologia , Astrócitos/enzimologia , Depressão/enzimologia , Hipocampo/metabolismo , Iodeto Peroxidase/deficiência , Animais , Expressão Gênica , Elevação dos Membros Posteriores , Iodeto Peroxidase/genética , Masculino , Camundongos Knockout , Condicionamento Físico Animal/fisiologia , Transcriptoma , Tri-Iodotironina/sangue , Iodotironina Desiodinase Tipo IIRESUMO
Reproductive physiology involves complex biological processes that can be disrupted by exposure to environmental contaminants. The effects of bisphenol A (BPA) on spermatogenesis and sperm quality is still unclear. The objective of this study was to investigate the reproductive toxicity of BPA at dosages considered to be safe (5 or 25mg BPA/kg/day). We assessed multiple sperm parameters, the relative expression of genes involved in the central regulation of the hypothalamic-pituitary-testicular axis, and the serum concentrations of testosterone, estradiol, LH and FSH. BPA exposure reduced sperm production, reserves and transit time. Significant damage to the acrosomes and the plasma membrane with reduced mitochondrial activity and increased levels of defective spermatozoa may have compromised sperm function and caused faster movement through the epididymis. BPA exposure reduced the serum concentrations of testosterone, LH and FSH and increased the concentration of estradiol. The relative gene expression revealed an increase in gonadotropin releasing hormone receptor (Gnrhr), luteinizing hormone beta (Lhb), follicle stimulating hormone beta (Fshb), estrogen receptor beta (Esr2) and androgen receptor (Ar) transcripts in the pituitary and a reduction in estrogen receptor alpha (Esr1) transcripts in the hypothalamus. In this study, we demonstrated for the first time that adult male exposure to BPA caused a reduction in sperm production and specific functional parameters. The corresponding pattern of gene expression is indicative of an attempt by the pituitary to reestablish normal levels of LH, FSH and testosterone serum concentrations. In conclusion, these data suggest that at dosages previously considered nontoxic to reproductive function, BPA compromises the spermatozoa and disrupts the hypothalamic-pituitary-gonadal axis, causing a state of hypogonadotropic hypogonadism.
Assuntos
Compostos Benzidrílicos/toxicidade , Sistema Hipotálamo-Hipofisário/efeitos dos fármacos , Fenóis/toxicidade , Espermatozoides/efeitos dos fármacos , Testículo/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Epididimo/efeitos dos fármacos , Epididimo/metabolismo , Estradiol/sangue , Receptor alfa de Estrogênio/genética , Receptor alfa de Estrogênio/metabolismo , Receptor beta de Estrogênio/genética , Receptor beta de Estrogênio/metabolismo , Hormônio Foliculoestimulante/sangue , Hormônio Luteinizante/sangue , Masculino , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/metabolismo , Ratos , Ratos Wistar , Receptores Androgênicos/genética , Receptores Androgênicos/metabolismo , Receptores LHRH/genética , Receptores LHRH/metabolismo , Reprodução/efeitos dos fármacos , Espermatogênese/efeitos dos fármacos , Espermatozoides/metabolismo , Testículo/metabolismo , Testosterona/sangueRESUMO
The purpose of the current study was to test the hypothesis that the dipeptidyl peptidase IV (DPPIV) inhibitor sitagliptin, which exerts anti-hyperglycemic and anti-hypertensive effects, upregulates GLUT4 translocation, protein levels, and/or mRNA expression in heart and skeletal muscle of spontaneously hypertensive rats (SHRs). Ten days of treatment with sitagliptin (40 mg/kg twice daily) decreased plasma DPPIV activity in both young (Y, 5-week-old) and adult (A, 20-week-old) SHRs to similar extents (~85%). However, DPPIV inhibition only lowered blood pressure in Y-SHRs (119 ± 3 vs. 136 ± 4 mmHg). GLUT4 translocation, total protein levels and mRNA expression were decreased in the heart, soleus and gastrocnemius muscle of SHRs compared to age-matched Wistar Kyoto (WKY) normotensive rats. These differences were much more pronounced between A-SHRs and A-WKY rats than between Y-SHRs and Y-WKY rats. In Y-SHRs, sitagliptin normalized GLUT4 expression in the heart, soleus and gastrocnemius. In A-SHRs, sitagliptin increased GLUT4 expression to levels that were even higher than those of A-WKY rats. Sitagliptin enhanced the circulating levels of the DPPIV substrate glucagon-like peptide-1 (GLP-1) in SHRs. In addition, stimulation of the GLP-1 receptor in cardiomyocytes isolated from SHRs increased the protein level of GLUT4 by 154 ± 13%. Collectively, these results indicate that DPPIV inhibition upregulates GLUT4 in heart and skeletal muscle of SHRs. The underlying mechanism of sitagliptin-induced upregulation of GLUT4 in SHRs may be, at least partially, attributed to GLP-1.
Assuntos
Dipeptidil Peptidase 4/metabolismo , Inibidores da Dipeptidil Peptidase IV/farmacologia , Transportador de Glucose Tipo 4/metabolismo , Coração/efeitos dos fármacos , Músculo Esquelético/efeitos dos fármacos , Regulação para Cima/efeitos dos fármacos , Animais , Pressão Sanguínea/efeitos dos fármacos , Peso Corporal/efeitos dos fármacos , AMP Cíclico/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Dipeptidil Peptidase 4/sangue , Peptídeo 1 Semelhante ao Glucagon/sangue , Glucose/metabolismo , Transportador de Glucose Tipo 4/genética , Homeostase/efeitos dos fármacos , Espaço Intracelular/efeitos dos fármacos , Espaço Intracelular/metabolismo , Masculino , Músculo Esquelético/metabolismo , Músculo Esquelético/patologia , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Fosforilação/efeitos dos fármacos , Transporte Proteico/efeitos dos fármacos , Pirazinas/farmacologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Ratos , Ratos Endogâmicos SHR , Transdução de Sinais/efeitos dos fármacos , Fosfato de Sitagliptina , Triazóis/farmacologiaRESUMO
ABSTRACT Measuring thyroid hormones is an important aspect for the study of metabolism and for monitoring diseases in both human and animal models. The traditional method for hormone measurement in rats is the radioimmunoassay (RIA). However, the RIA is associated with some practical disadvantages, including the use of radioactive material, the need for specialized equipment and expert staff, the short shelf-life of kits according to the half-life of the radioisotope and high costs. The objective of this study was to develop a new cost-effective method for measuring TSH levels in rats that avoids the use of radioactive material. We developed an in-house competitive immunoassay using a reference standard, polyclonal antibody produced in rabbits and biotinylated antigen. This method was tested in 64 Wistar rats that were divided into a control group (n = 41) and a group with hypothyroidism (n = 23). Our assay demonstrated an analytical sensitivity of 0.24 ng/mL (n = 12) and an intra-assay coefficient of variation (CV) of 8.9% for sera with TSH levels of 1.5 ng/mL and 13.2% for sera with TSH levels of 17.5 ng/mL (n = 14). The inter-assay CV was 13.5% for sera with TSH levels of 1.4 ng/mL and 14.5% for TSH levels of 18.2 ng/mL (n = 5). The analysis of mean TSH levels in control rats (5.06 ± 0.5701) and hypothyroid rats (51.09 ± 5.136) revealed a statistically significant difference (p < 0.001) between the groups. This method showed good sensitivity, can be automated and is low-cost compared with RIA. Our method offers a viable alternative for TSH measurement in rats.