The effects of Crocus sativus extract on inhaled paraquat-induced lung inflammation, oxidative stress, pathological changes and tracheal responsiveness in rats.

Paraquat is a green liquid toxin that is used in agriculture and can induce multi-organ including lung injury. Various pharmacological effects of Crocus sativus (C. sativus) were indicated in previous studies. In this research, the effects of C. sativus extract and pioglitazone on inhaled paraquat-induced lung inflammation, oxidative stress, pathological changes, and tracheal responsiveness were studied in rats. Eight groups of rats (n = 7 in each) including control (Ctrl), untreated paraquat aerosol exposed group (54 mg/m3, 8 times in alternate days), paraquat treated groups with dexamethasone (0.03 mg/kg/day, Dexa) as positive control, two doses of C. sativus extract (20 and 80 mg/kg/day, CS-20 and CS-80), pioglitazone (5 and 10 mg/kg/day, Pio-5 and Pio-10), and the combination of CS-20 + Pio-5 were studied. Total and differential WBC, levels of oxidant and antioxidant biomarkers in the BALF, lung tissue cytokine levels, tracheal responsiveness (TR), and pathological changes were measured. The levels of IFN-γ, IL-10, SOD, CAT, thiol, and EC50 were reduced, but MDA level, total and differential WBC count in the BALF and lung pathological changes were increased in the paraquat group (all, p < 0.001). The levels of IFN-γ, IL-10, SOD, CAT, thiol and EC50 were increased but BALF MDA level, lung pathological changes, total and differential WBC counts were reduced in all treated groups. The effects of C. sativus high dose and combination groups on measured parameters were equal or even higher than dexamethasone (p < 0.05 to p < 0.001). The effects of the combination of CS-20 + Pio-5 on most variables were significantly higher than CS-20 and Pio-5 alone (p < 0.05 to p < 0.001). C. sativus treatment improved inhaled paraquat-induced lung injury similar to dexamethasone and showed a synergistic effect with pioglitazone, suggesting possible PPAR-γ receptor-mediated effects of the plant.

Dose-dependent effects of prenatal exposure of pioglitazone, the PPARγ agonist, on the hippocampus development and learning and memory performance of rat offspring.

It is known that pioglitazone, defined as a PPARγ agonist, has neuron-protective properties in nervous system disorders. The aim of this study is to investigate the effects of pioglitazone administration at different doses during prenatal period on the neurons, glial cells and learning-memory levels in the hippocampus of rat offspring. Pregnant rats were divided into three groups; Low-Dose Pioglitazone (LDP), High-Dose Pioglitazone (HDP) and control (C) (n = 3). Pregnant rats in the HDP and LDP groups were given pioglitazone at 30 mg/kg and 5 mg/kg doses, respectively, by gavage once a day during their pregnancy. No procedure was applied to the rats in the control group. Morris water tank test was applied to offspring obtained from postnatal 24th to 28th day. The offspring were sacrificed on the 29th postal day and their brain tissues removed. Stereological, histopathological and immunohistochemical techniques were used to analyze brain tissues. As a result of the analysis, it was observed that there were delays in learning and memory, the number of pyramidal neurons decreased, and the density of cells stained with glial fibrillar acidic protein (GFAP) positive increased in the HDP group compared to the other groups (p < 0.05). No significant difference was found between the LDP and control groups in terms of these parameters (p > 0.05). Our results showed that pioglitazone administered in the prenatal period had an effect on the hippocampus development and learning and memory performance of rats, depending on the dose.

Toxicity of Pioglitazone on Mitochondria Isolated from Brain and Heart: An Analysis for Probable Drug-Induced Neurotoxicity and Cardiotoxicity.

Pioglitazone (PG) is one of the thiazolidinedione (TZDs) drugs used in diabetic patients. TZDs are known as peroxisome proliferator-activated receptor gamma (PPARγ) agonists. Mitochondria are considered as one of the targets of these drugs. The mechanisms of the effect of PG on mitochondria are not well understood. In this study, we investigated the effect of PG on mitochondria isolated from brain and heart. Mitochondrial parameters such as succinate dehydrogenase (SDH) activity, reactive oxygen species (ROS) generation, collapse in mitochondrial membrane potential (MMP), mitochondrial swelling and cytochrome c release were evaluated. The results showed that PG at concentrations of 12.5, 25 and 50 µg/ml increased the generation of ROS, the collapse of MMP, mitochondrial swelling and the release of cytochrome c in mitochondria isolated from both brain and heart tissues. The underlying mechanisms of PG induced neuro-toxicity and cardio-toxicity may be associated with changes in mitochondrial function, ROS generation (oxidative stress), and changes in the mitochondrial membrane.

Augmentation of cadmium-induced oxidative cytotoxicity by pioglitazone in renal tubular epithelial cells.

The aim of this study was to examine whether a peroxisome proliferator-activated receptor (PPAR)-γ agonist could affect cadmium (Cd)-induced cytotoxicity via the increased expression of megalin, one of the uptake pathways, using renal epithelial LLC-PK1 cells. The treatment with 1 µM Cd for 24 h was not cytotoxic; however, when the cells were pretreated with 0.1 µM pioglitazone for 12 h and then exposed to 1 µM Cd for 24 h, significant accumulation of Cd and cytotoxicity were detected, with an increase in megalin mRNA expression. In addition, pretreatment with pioglitazone significantly increased the Cd-induced generation of hydrogen peroxide and cell apoptosis. The augmented Cd-induced cytotoxicity and apoptosis on preincubation with pioglitazone were inhibited by prior treatment with GW 9662 (PPAR-γ antagonist). These findings suggest that a PPAR-γ agonist could augment Cd-induced oxidative injury and cell apoptosis, possibly dependent on the expression level of the uptake pathway.

Editor's Highlight: An Impaired Immune Tolerance Animal Model Distinguishes the Potential of Troglitazone/Pioglitazone and Tolcapone/Entacapone to Cause IDILI.

We have developed an animal model of amodiaquine-induced liver injury that has characteristics very similar to idiosyncratic drug-induced liver injury (IDILI) in humans by impairing immune tolerance using a PD1-/- mouse and cotreatment with anti-CTLA-4. In order to test the usefulness of this model as a general model for human IDILI risk, pairs of drugs with similar structures were tested, one of which is associated with a relatively high risk of IDILI and the other not. One such pair is troglitazone and pioglitazone; troglitazone has caused fatal cases of IDILI while pioglitazone is quite safe. Another pair is tolcapone and entacapone; tolcapone can cause serious IDILI; in contrast, although entacapone has been reported to cause liver injury, it is relatively safe. PD1-/- mice treated with anti-CTLA-4 and troglitazone or tolcapone displayed liver injury as determined by ALT levels and histology, while pioglitazone and entacapone showed less signs of liver injury. One possible mechanism by which drugs could induce an immune response leading to IDILI is by causing the release of danger-associated molecular pattern molecules that activate inflammasomes. We found that the supernatants from incubations of troglitazone, tolcapone, or entacapone with hepatocytes were also able to activate inflammasomes in macrophages, while the supernatant from pioglitazone incubations did not. These results are consistent with an immune mechanism for troglitazone- and tolcapone-induced IDILI and add to the evidence that this may be a general model for IDILI.