Effect of growth hormone on kidney growth and glomerular structure

Chlorogenic acid abates oxido-inflammatory and apoptotic responses in the liver and kidney of Tamoxifen-treated rats

Plant-derived phenolics are utilized as chemopreventive agents to abate adverse toxic responses associated with drug-induced damages. Tamoxifen (TAM)-a chemotherapeutic agent-is used in managing all stages of hormone-dependent breast cancer. Notwithstanding TAM's clinical side effect-including hepatic toxicity-its use is commonplace. The present study investigates the effect of Chlorogenic acid (CGA: 25 and 50 mg kg-1; per os (p.o)) reported to exhibit various beneficial properties, including antioxidative effect against TAM (50 mg/kg; p.o.)-induced hepatorenal toxicities in rats treated as follows: Control, CGA, or TAM alone, and rats co-treated with CGA and TAM for 2 weeks. Biomarkers of hepatorenal function, oxido-inflammatory stress, and hepatorenal histopathology were performed. We observed that TAM alone decreased relative organ weights (ROW), marginally impacted rat's survivability, and significantly (P < 0.05) increased hepatorenal toxicities and reactive oxygen and nitrogen species (RONS). TAM decreased (P < 0.05) antioxidant, anti-inflammatory cytokine (IL-10), besides increase in (P < 0.05) lipid peroxidation (LPO), pro-inflammatory cytokines (IL-1β, TNF-α), nitric oxide (NO), xanthine oxidase (XO), myeloperoxidase (MPO), and apoptotic caspases (Casp-3 and -9) levels. These biochemical alterations were accompanied by morphological lesions in experimental rats' liver and kidney. Conversely, that CGA dose-dependently relieved TAM-mediated toxic responses, restored antioxidants capacities, reduced oxidative stress, pro-inflammatory cytokines levels, and Casp-3 and -9 activities in experimental rats. Furthermore, CGA protected against lesions observed in the liver and kidney of rats treated with TAM alone. Overall, CGA blocked TAM-mediated hepatorenal injuries associated with pro-oxidative, inflammatory, and apoptotic mechanisms. CGA may serve as a chemoprotective agent boosting patients prognosis undergoing TAM chemotherapy.

Growth hormone receptor abundance in tibial growth plates of uremic rats: GH/IGF-I treatment

BACKGROUND

Children with chronic renal failure (CRF) exhibit growth retardation and a disturbed growth hormone/insulin-like growth factor-I (GH/IGF-I) axis. Treatment of children with CRF with GH or GH/IGF-I can partially restore linear growth. The molecular basis for decreased longitudinal growth is not known but may involve an impaired action of GH.

METHODS

We used the growth-retarded uremic rat model to determine the abundance and distribution of GH receptors (GHRs) in the tibial epiphyseal growth plate and the influence of GH, IGF-I, or combined GH/IGF-I treatment. Pair-fed rats were used as the control.

RESULTS

While all treatment regimes increased body length and weight in both rat groups, only GH/IGF-I treatment increased the total growth plate width. This involved an increase in cell number in the hypertrophic zone, which could also be induced by IGF-I alone. Immunohistochemical analysis showed that uremic rats had decreased abundance of GHRs in the proliferative zone, and only GH/IGF-I therapy could overcome this decrease. These data thus suggest that growth retardation in uremic rats is, at least in part, due to a decrease in GHR abundance in chondrocytes of the proliferative zone of the tibial growth plate. This decreased GHR abundance can be overcome by combined GH/IGF-I therapy, thus enhancing generation and proliferation of hypertrophic zone chondrocytes and increasing growth-plate width.

CONCLUSION

These studies point to a mechanism for the growth retardation seen in children with CRF, and suggest that combined GH/IGF-I treatment may provide more effective therapy for these patients than GH alone.

Growth hormone and insulin-like growth factor-I and mesangial matrix in uremic rats

Combined growth hormone (GH) and insulin-like growth factor-I (IGF-I) therapy has been advocated for clinical use to minimize the diabetogenic effect of GH and enhance their anabolic effects. However, GH has been shown to accelerate the development of glomerular sclerosis in experimental animals and IGF-I mediates the renal effects of GH. The purpose of this study was therefore to examine morphometrically the effects of GH (1 mg intraperitoneally three times a week), IGF-I (50 micrograms/kg body weight subcutaneously twice a day), and combined GH/IGF-I treatments in vivo on mesangial matrix at 3-20 days after 5/6 nephrectomy in 140- to 150-g rats. There were no significant changes in growth and renal function after GH and/or IGF-I treatment. The effects of GH and IGF-I on glomerular size were additive, which were more prominent in juxtamedullary glomeruli. GH induced proportional increases in mesangial area (MA) and glomerular area (GA), whereas IGF-I induced a similar increase in GA without a corresponding change in MA. When compared with GH treatment alone, combined GH/ IGF-I treatment resulted in a lesser degree of mesangial expansion despite an enhanced glomerular size. While additional studies are needed to examine the long-term effects of these findings, our results suggest a potentially beneficial effect of combined GH/IGF-I therapy during uremia.

Chronic Low Dose Growth Hormone Treatment Stimulates Both Hypertrophy and Hyperplasia of Remnant Kidneys in Uraemic Rats

CONCLUSION

In conclusion, low doses of exogenous rhGH, when administered in a manner similar to clinical practice, are associated with glomerular enlargement and stimulation of hypertrophy and hyperplasia of remnant kidneys from uraemic rats. Increased GV was also seen after short term, high dose rhGH therapy in our previous study.([4]) The time interval required before increased GV develops with low dose rhGH therapy and whether or not further rhGH exposure subsequently leads to worsening glomerular hypertrophy, glomerulosclerosis([7]) and renal failure cannot be determined from the current study. Although we observed no significant changes in renal function with rhGH therapy, we recommend that children with CRI be carefully monitored to ensure that long term rhGH treatment has no such deleterious effects.

Enhanced body growth in uremic rats treated with IGF-I and growth hormone in combination

The efficacy of seven days treatment with IGF-I (1.7 mg/kg/day), growth hormone (GH) (2 mg/kg/day), IGF-I+GH (1.7 mg/kg/day + 2 mg/kg/day) or vehicle, in promoting growth was investigated in female Sprague-Dawley rats with 5/6 nephrectomies (N = 8 per group). Treatment commenced after chronic renal failure had been present for seven weeks. Significant increases in body weight gain were found in all groups versus control, with IGF-I+GH causing the greatest response, and increased body weight gains correlating with increased nitrogen retention. GH treatment alone significantly stimulated food intake. IGF-I+GH resulted in close to additive increases in food conversion efficiency (18.8%, 21.5% and 39.6% increases with IGF-I, GH and IGF-I+GH, respectively, over control levels) and longitudinal bone growth (39%, 37% and 67% increases with IGF-I, GH and IGF-I+GH, respectively, vs. control). Serum insulin and cholesterol levels significantly decreased with IGF-I and IGF-I+GH treatment. Creatinine clearance did not change, suggesting there were no effects of treatment on kidney function. Although IGF-I at the doses used did not result in a greater anabolic response than GH, IGF-I+GH caused significantly enhanced growth while reducing serum insulin and cholesterol levels.