Hypothalamus Of Rats With Chronic Renal Failure Orexin A And Its Receptor, Leptin Receptor And Neuropeptide Y Level Changes

The causes of anorexia in patients with chronic renal failure(CRF) remains unclear. Neuropeptides regulating orexia have been paid much attention to in CRF.Orexin A and B are two newly discovered hypothalamic neuropeptides which may stimulate food consumption. Hypothalamus orexin A levels in CRF has never been reported. The main aim of this study is to examine the change in orexin A, orexin receptor 1 (OX₁R), neuropeptide Y(NPY) and leptin receptor of hypothalamus in CRF rats.Methods 1. 41 male Wister rats weighing 200-250g were divided into three groups:1.Normal(n=5). 2.Sham-operated (n=15). 3.CRF group(5/6 nephrectoized, n=21). 5-8 rats in group 2 and 3 were decapitated and their hypothalamus removed rapidly at week 4,8,12, respectively. Serum and plasma were used for biochemical and Orexin A, neuropeptide Y measurements.The tissue were extracted by acidified, boiled, homogenized, centrifiiged and lyophilized to powder. Plasma was applied to Sep-Pak C18 catridges and then lyophilized to powder. All the powder was reconstituted in assay buffer and determined by radioimmunnoassay.Plasma and tissue neuropeptide Y were also assayed by radioimmunnoassay.2.11 male Wister rats weighing 200-250g were divided into two groups: 1 .Sham-operated (n=5). 2.CRF group(5/6 nephrectoized, n=6). Rats in both groups were decapitated and their hypothalamus removed rapidly at week 12. Serum was used for creatinine measurement.The expression of Prepro-orexin mRNA (Prepro-OX mRNA) and OX₁R mRNA in hypothalamus was measured by RT-PCR.3.10 male Wister rats weighing 200-250g were divided into two groups:1.Sham-operated (n=5). 2.CRF group(5/6 nephrectoized, n=5). Rats in both groups were decapitated and their hypothalamus removed rapidly at week 8. Serum was used for creatinine measurementThe expression of orexin A, Orexin receptor 1 and ob-Rb in hypothalamus was assayed by immunohistochemistry.Results 1.The serum creatinine levels in CRF rats were markedly higher than those of sham-operated rats (2.0±1.1 vs 0.8±0.07 at week 8 and2.49±1.33 vs 0.82±0.17 at week12, respectively). Plasma orexin A levels of CRF rats were significantly higher than those of sham-operated at week 12 (263.61±62.01 vs 183.33 pg/ml,p=0.039).The hypothalamus orexin A levels of CRF rats were lower than those of sham-operation at week 8 (12.74±2.55vs17.65 ± 4.75fmol/mg wet weight, p=0.087) and significantly lower than those of sham-operation at week 12 (10.47±2.69 vs 17.37±3.94fmol/mg wet weight,p=0.023) .Plasma neuropeptide Y levels of CRF rats were significantly higher than those of sham-operated at week 8 (7.06 ±1.67 vs 4.99±...