RESUMEN
The prevalence of atherosclerotic cardiovascular disease in chronic hemodialysis (HD) patients has been demonstrated to be higher than in healthy people. Severe liver fibrosis is strongly associated with early carotid atherosclerosis and it might reduce the survival of patients who undergo both renal replacement therapy and transplantation. We wanted to assess whether nonalcoholic fatty liver disease (NAFLD) was associated with altered intima-media thickness (IMT) in HD patients as an independent marker of subclinical atherosclerosis. We enrolled 42 patients undergoing HD and 48 patients with normal renal function, all of them with high levels of aminotransferases and an ultrasonographic diagnosis of liver steatosis. The control group consisted of 60 healthy subjects. Laboratory tests for inflammatory and oxidative markers, ultrasonographic liver evaluation, carotid IMT measurement, and liver biopsy were performed. Different degrees of fibrosis were detected in our study cohort. Worse liver histopathological scores and higher plasmatic levels of C-reactive protein, reactive oxygen species, and vascular cell adhesion molecule-1 were found in HD patients. Carotid IMT was significantly higher (p < 0.005) in patients with histological steatosis. HD patients may develop active and progressive chronic hepatitis faster than patients with normal renal function and the thickness of their carotid intima-media might be markedly increased. These two conditions seem to be independent on classical risk factors and on metabolic syndrome. They might be related to the high levels of oxidants and to the inflammatory state, which are typical of patients undergoing HD. Independently related with the traditional risk factors for cardiovascular disease, nonspecific inflammation and oxide-reductive imbalance may play an important role in the progression of NAFLD and atherosclerotic disease in HD patients.
RESUMEN
In 8- and 20-month-old male rats, treated or not with growth hormone (GH) for 4 days, simultaneous evaluation of hypothalamic GH-releasing hormone (GHRH) and somatostatin (SS) gene expression, GH secretion from anterior pituitaries (APs) in vitro (basal and GHRH-stimulated) and plasma IGF-I levels was performed. Twenty-month-old rats showed decreased GHRH mRNA levels, decreased GH secretion from APs in vitro (not responsive to GHRH stimulation) and reduced plasma IGF-I levels as compared to younger counterparts. SS mRNA levels were only slightly reduced in the hypothalamus of aged rats. Short-term administration of biosynthetic human GH (125 microgram/rat, twice daily, IP) to 8-month-old rats abolished the in vitro GHRH-stimulated GH release from APs and altered GH regulatory neuropeptides gene expression, i.e., reducing GHRH mRNA levels and increasing SS mRNA levels. In 20-month-old rats, hGH administration increased plasma IGF-I levels but did not change significantly GHRH and SS gene expression. These data indicate that the feedback effects exerted by circulating GH on GHRH and SS neurons, while evident in adult rats, are not detectable in aged rats.