Investigation of the mutual crosstalk between ER stress and PI3K/AKT/mTOR signaling pathway in iron overload-induced liver injury in chicks.

Iron is an essential element for the normal functioning of living organisms, but excessive iron deposition can lead to organ damage. This study aims to investigate the interaction between the endoplasmic reticulum stress signaling pathway and the PI3K/AKT/mTOR signaling pathway in liver injury induced by iron overload in chicks. Rspectively, 150 one-day-old broilers were divided into three groups and supplemented with 50 (C), 500 (E1), and 1000 (E2) mg ferrous sulfate monohydrate/kg in the basal diet. Samples were taken after continuous feeding for 14 days. The results showed that iron overload could upregulate the levels of ALT and AST. Histopathological examination revealed bleeding in the central vein of the liver accompanied by inflammatory cell infiltration. Hoechst staining showed that the iron overload group showed significant bright blue fluorescence, and ultrastructural observations showed chromatin condensation as well as mitochondrial swelling and cristae disorganization in the iron overload group. RT-qPCR and Western blot results showed that iron overload upregulated the expression of Bax, Caspase-3, Caspase-9, GRP78, GRP94, P-PERK, ATF4, eIF2α, IRE1, and ATF6, while downregulating the expression of Bcl-2 and the PI3K/AKT/mTOR pathway. XBP-1 splicing experiment showed significant splicing of XBP-1 gene after iron overload. PCA and correlation analysis suggested a potential association between endoplasmic reticulum stress, the PI3K/AKT/mTOR signaling pathway, and liver injury in chicks. In summary, iron overload can induce cell apoptosis and liver injury by affecting endoplasmic reticulum stress and the PI3K/AKT/mTOR signaling pathway.

[Toxic effects of combination of Aconiti Lateralis Radix Praeparata with Trichosanthis Fructus on inflammatory response and myocardial fibrosis in pressure overload rats based on ß2-AR/PKA signal].

To study the effects of combination of Aconiti Lateralis Radix Praeparata( Fuzi) with Trichosanthis Fructus( Gualou) on cardiac function,electrocardiogram,inflammatory response and myocardial fibrosis in pressure overload( PO) rats,and further explore the mechanism based on ß2-AR/PKA signaling. PO rat model was established by constricting the abdominal aorta. Twelve weeks after the operation,these rats were randomly divided into model goup( PO),low dose Fuzi group( FL,5. 4 g·kg-1·d-1),Gualou group( GL,5. 4 g·kg-1·d-1),Fuzi and Gualou combination group( FG,5. 4 g·kg-1·d-1+5. 4 g·kg-1·d-1) and high dose Fuzi group( FH,10. 8 g·kg-1·d-1). At the same time,sham operation group was set. After intervention for 6 weeks,carotid blood pressure,cardiac function,electrocardiogram and heart mass index were measured. HE staining was used to observe the inflammatory response in the rat heart and kidney. Masson staining was used to determine the myocardial fibrosis. Western blot was used to detect the protein expression of ß2-AR and PKA. As compared with sham operation group,the blood pressure and heart mass index were obviously increased in PO model group,but there was no significant difference in various treatment groups in the above indexes. As compared with PO model group,FH treatment significantly increased the ejection fraction( EF) and GL treatment effectively enhanced the cardiac output( CO),but other treatment groups had no significant effect on these parameters. Moreover,FG treatment can synergistically attenuate QT and QTc internal prolongation,but it also aggravated inflammatory response in the heart and kidney tissues and promoted myocardial fibrosis as compared to FZ or GL alone treatment,with toxic effects equivalent to FH treatment group. Following FG and FH treatment,simultaneously,ß2-AR and PKA protein levels were significantly elevated,indicating that the increasing toxicity of FG could be associated with activation of ß2-AR/PKA signaling. These results suggested that combination of FZ and GL could synergistically enhance toxicity of FZ in special pathological states such as pressure overload,and caution should be taken in clinical application.

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels regulate firing of globus pallidus neurons in vivo.

The globus pallidus plays a significant role in motor control under both health and pathological states. Recent studies have revealed that hyperpolarization-activated cyclic nucleotide-gated (HCN) channels occupy a critical position in globus pallidus pacemaking activity. Morphological studies have shown the expression of HCN channels in the globus pallidus. To investigate the in vivo effects of HCN channels in the globus pallidus, extracellular recordings and behavioral tests were performed in the present study. In normal rats, micro-pressure ejection of 0.05mM ZD7288, the selective HCN channel blocker, decreased the frequency of spontaneous firing in 21 out of the 40 pallidal neurons. The average decrease was 50.4±5.4%. Interestingly, in another 18 out of the 40 pallidal neurons, ZD7288 increased the firing rate by 137.1±27.6%. Similar bidirectional modulation on the firing rate was observed by a higher concentration of ZD7288 (0.5mM) as well as another HCN channel blocker, CsCl. Furthermore, activation of HCN channels by 8-Br-cAMP increased the firing rate by 63.0±9.3% in 15 out of the 25 pallidal neurons and decreased the firing rate by 46.9±9.4% in another 8 out of the 25 pallidal neurons. Further experiments revealed that modulation of glutamatergic but not GABAergic transmission may be involved in ZD7288-induced increase in firing rate. Consistent with electrophysiological results, further studies revealed that modulation of HCN channels also had bidirectional effects on behavior. Taken together, the present studies suggest that HCN channels may modulate the activity of pallidal neurons by different pathways in vivo.

KIM-1 and NGAL as biomarkers of nephrotoxicity induced by gentamicin in rats.

Gentamicin is a member of aminoglycosides, which has represented highly effective antimicrobial agents especially in Gram-negative infections despite their toxic effects in the kidney. Rapid diagnosis is vital to preserve renal function and to slow down renal injury. Owing to the poor sensitivity and specificity of serum creatinine (SCr) and blood urea nitrogen (BUN), new biomarkers for earlier and more accurate detection are needed. The aim of our study was to determine whether kidney injury molecule-1 (KIM-1) and neutrophil gelatinase-associated lipocalin (NGAL) may be useful biomarkers in the assessment of gentamicin-induced nephrotoxicity in rats. In this study, the two biomarkers of renal toxicity were assessed via ELISA, quantitative real-time PCR, and immunohistochemistry in rats treated with gentamicin for up to 7 days. Repeated administration of gentamicin to male SD rats for 1, 3, or 7 days resulted in a dose- and time-dependent increase in the expression of KIM-1 and NGAL. Changes in gene and protein expressions were found to correlate with the progressive histopathological alterations and preceded effects on traditional clinical parameters indicative of impaired kidney function. Both of the biomarkers are supported to be used as sensitive indicators of acute kidney injury caused by gentamicin.

Endogenous HCN Channels Modulate the Firing Activity of Globus Pallidus Neurons in Parkinsonian Animals.

The globus pallidus occupies a critical position in the indirect pathway of the basal ganglia motor control system. Hyperpolarization-activated cyclic-nucleotide gated (HCN) channels play an important role in the modulation of neuronal excitability. In vivo extracellular single unit recording, behavioral test and immunohistochemistry were performed to explore the possible modulation of endogenous HCN channels in the globus pallidus under parkinsonian states. In MPTP parkinsonian mice, micro-pressure application of the selective HCN channel antagonist, ZD7288, decreased the firing rate in 10 out of the 28 pallidal neurons, while increased the firing rate in another 15 out of the 28 neurons. In 6-OHDA parkinsonian rats, ZD7288 also bidirectionally regulated the spontaneous firing activity of the globus pallidus neurons. The proportion of pallidal neurons with ZD7288-induced slowing of firing rate tended to reduce in both parkinsonian animals. Morphological studies revealed a weaker staining of HCN channels in the globus pallidus under parkinsonian state. Finally, behavioral study demonstrated that intrapallidal microinjection of ZD7288 alleviated locomotor deficits in MPTP parkinsonian mice. These results suggest that endogenous HCN channels modulate the activities of pallidal neurons under parkinsonian states.