RESUMEN
The mechanisms involved in sudden animal death due to acute heart failure during heat stress are not well understood. We examined the relationship between heat stress-induced variations of protective Hsp60 and expression of its regulatory factor, HSF-1, in heat-stressed primary myocardial cells of neonatal rats in vitro through cardiac enzyme detection, immunoblotting, immunocytochemistry, and qPCR. Increases in cardiac damage-related enzyme levels demonstrated injury to myocardial cells after heat exposure at 42°C. Hsp60 expression levels fluctuated during heat stress; they decreased significantly after 20 min, then increased at 120 min and decreased again at 360 min after initiation of heat stress. The highest levels of Hsp60 were observed at 240 min, while the lowest were at 60 min. Damage to myocardial cells was characterized by increases in cardiac enzyme levels and low levels of Hsp60 due to functional disorder of myocardial cells at early stages of heat stress. However, the significant induction of hsp60 mRNA levels from the beginning up to 240 min of heat stress was not consistent with the classic regulatory mechanisms that link transcription and translation, suggesting that Hsp60 expression is delayed due to loss of Hsp60 during the early stages of heat stress. hsf-1 mRNA levels were significantly increased from 10 min of heat stress; however, HSF-1 protein levels did not simultaneously increase, indicating that HSF-1 is not the sole regulator of Hsp60 expression.
Asunto(s)
Chaperonina 60/genética , Proteínas de Unión al ADN/genética , Respuesta al Choque Térmico/genética , Proteínas Mitocondriales/genética , Factores de Transcripción/genética , Animales , Chaperonina 60/biosíntesis , Proteínas de Unión al ADN/metabolismo , Regulación de la Expresión Génica , Factores de Transcripción del Choque Térmico , Respuesta al Choque Térmico/fisiología , Humanos , Proteínas Mitocondriales/biosíntesis , Miocardio/citología , Miocardio/metabolismo , ARN Mensajero/genética , Ratas , Factores de Transcripción/metabolismoRESUMEN
Haemonchus contortus is one of the most important parasites that infects sheep and exerts its pathogenic effects by sucking blood, causing disturbances of organ-functions and thus inducing alterations in various normal physiological parameters. Changes in live body weight, faecal egg count, kinetics of circulating eosinophils and PCV value were studied at weekly interval for a period of 84 days in 18 lambs of local breed after infection with a single dose of 5000 H. contortus (L(3)). In the two groups of lambs infected with nematodes both non-treated and treated with ivermectin (HcNT and HcIT), similar egg excretion patterns was observed starting from third week after infection, with a regular increase in FEC. Examination of whole abomasum of each animal revealed no developmental stage of nematode from treated and control lambs on day 84. The total mean number of H. contortus worms recovered at necropsy from abomasa of untreated infected lambs (group HcNT) was 2576.2 (+/-221.0). The significant loss of body weight, development of heavy worm burden and severe anaemia as indicated by reduced PCV in untreated infected lambs indicated high susceptibility of the lambs to H. contortus. On the other hand, complete absence of the parasite, improved PCV value and body weight after treatment of infected animals (HcIT) proved 100% efficacy of ivermectin against H. contortus.