Protective effect of histidine by inhibition of gossypol on rat's liver LDH-5

Effects of sublethal doses of gossypol on haematological properties and biochemical metabolites of male rabbit

The purpose of this study was to investigate the effects of two sublethal doses of gossypol (GOS) (4 and 20 mg/kg of body weight), administered every other day, on some haematological, biochemical, enzymatic and electrolytic properties and amino and fatty acids in male rabbit blood plasma. The experiment lasted for 16 wk and included two phases: 1) administration period; rabbits were given the experimental doses of GOS for 8 wk; and 2) recovery period; rabbits were allowed 8 wk for complete withdrawal of drugs from the plasma. Results showed that low levels of gossypol increased (<em>P</em>&lt;0.01) haemoglobin, mean corpuscular haemoglobin and white blood cells compared to control. Plasma total protein was increased (<em>P</em>&lt;0.01) by the low GOS dose in both experimental phases. Likewise, glucose concentration was increased (<em>P</em>&lt;0.01) by the high GOS dose during the recovery period. Aspartate aminotransferase and alanine aminotransferase enzymes were increased (<em>P</em>&lt;0.01) by the high dose of GOS treatment only. Low GOS dose increased (<em>P</em>&lt;0.01) blood plasma Na+ concentration in the recovery period only. Results revealed that total essential amino acids (EAA), and EAA/non-EAA ratio were not affected in a dose-dependent manner during the treatment phase expect for plasma proline, which was increased along with non-EAA (<em>P</em>&lt;0.01) by high GOS dose. Additionally, GOS administration did not affect total unsaturated fatty acids (USFA), total saturated fatty acids (SFA) and SFA/USFA ratio in a dose-dependent manner. In conclusion, Gossypol treatment affected rabbit haematological parameters and biochemical properties of blood plasma in a dose-dependent manner.

Pharmacologic inhibition of lactate production prevents myofibroblast differentiation

Myofibroblasts are one of the primary cell types responsible for the accumulation of extracellular matrix in fibrosing diseases, and targeting myofibroblast differentiation is an important therapeutic strategy for the treatment of pulmonary fibrosis. Transforming growth factor-β (TGF-β) has been shown to be an important inducer of myofibroblast differentiation. We previously demonstrated that lactate dehydrogenase and its metabolic product lactic acid are important mediators of myofibroblast differentiation, via acid-induced activation of latent TGF-β. Here we explore whether pharmacologic inhibition of LDH activity can prevent TGF-β-induced myofibroblast differentiation. Primary human lung fibroblasts from healthy patients and those with pulmonary fibrosis were treated with TGF-β and or gossypol, an LDH inhibitor. Protein and RNA were analyzed for markers of myofibroblast differentiation and extracellular matrix generation. Gossypol inhibited TGF-β-induced expression of the myofibroblast marker α-smooth muscle actin (α-SMA) in a dose-dependent manner in both healthy and fibrotic human lung fibroblasts. Gossypol also inhibited expression of collagen 1, collagen 3, and fibronectin. Gossypol inhibited LDH activity, the generation of extracellular lactic acid, and the rate of extracellular acidification in a dose-dependent manner. Furthermore, gossypol inhibited TGF-β bioactivity in a dose-dependent manner. Concurrent treatment with an LDH siRNA increased the ability of gossypol to inhibit TGF-β-induced myofibroblast differentiation. Gossypol inhibits TGF-β-induced myofibroblast differentiation through inhibition of LDH, inhibition of extracellular accumulation of lactic acid, and inhibition of TGF-β bioactivity. These data support the hypothesis that pharmacologic inhibition of LDH may play an important role in the treatment of pulmonary fibrosis.

Molecular approach of gossypol-induced reproductive toxicity in male rabbits. Changes in seminal plasma amino acids and fatty acids

This study was done to evaluate the effects of two sublethal doses of gossypol (4 and 20 mg/kg of BW, every other day) on some amino and fatty acid concentrations in male rabbit seminal plasma. Rabbits were chosen as an experimental animal owing to the fact that they are excellent model for reproductive toxicological effects. The experiment lasted 16 weeks and included two periods: a treatment period (first 8 weeks) where the animals were given the tested product, and a recovery period (second 8 weeks) where all drugs were withdrawn. Results showed that total amino acids (TAA), total essential amino acids (EAA), total non-essential amino acids (non-EAA) and EAA/non-EAA ratio were decreased in a dose-dependent manner during gossypol treatment. The deleterious effect on TAA concentrations was mainly due to the reduction in total EAA. However, these concentrations regained their normal values after gossypol cessation. Basic, acidic, neutral amino acids and basic/acidic amino acids ratio decreased in a dose-dependent manner by gossypol treatment. Additionally, gossypol administration caused decreases in total unsaturated fatty acids (USFA) and increases in total saturated fatty acids (SFA) and the SFA/USFA ratio in a dose-dependent manner. During the recovery period, total SFA and USFA showed significant reduction and significant increase, respectively, after gossypol withdrawal. In conclusion, gossypol administration affected rabbit seminal plasma concentrations of amino and fatty acids in a dose-dependant manner. Gossypol reduced TAA, total EAA and total non-EAA. Additionally, gossypol caused decreases in total USFA and increases in total SFA. These deleterious effects were associated with poor-quality semen observed in our previous studies.