Berberine alleviates the cerebrovascular contractility in streptozotocin-induced diabetic rats through modulation of intracellular Ca²⁺ handling in smooth muscle cells

Natural L-type calcium channels antagonists from Chinese medicine

L-type calcium channels (LTCCs), the largest subfamily of voltage-gated calcium channels (VGCCs), are the main channels for Ca2+ influx during extracellular excitation. LTCCs are widely present in excitable cells, especially cardiac and cardiovascular smooth muscle cells, and participate in various Ca2+-dependent processes. LTCCs have been considered as worthy drug target for cardiovascular, neurological and psychological diseases for decades. Natural products from Traditional Chinese medicine (TCM) have shown the potential as new drugs for the treatment of LTCCs related diseases. In this review, the basic structure, function of LTCCs, and the related human diseases caused by structural or functional abnormalities of LTCCs, and the natural LTCCs antagonist and their potential usages were summarized.

A Mechanistic Review on How Berberine Use Combats Diabetes and Related Complications: Molecular, Cellular, and Metabolic Effects

Berberine (BBR) is an isoquinoline alkaloid that can be extracted from herbs such as Coptis, Phellodendron, and Berberis. BBR has been widely used as a folk medicine to treat various disorders. It is a multi-target drug with multiple mechanisms. Studies have shown that it has antioxidant and anti-inflammatory properties and can also adjust intestinal microbial flora. This review focused on the promising antidiabetic effects of BBR in several cellular, animal, and clinical studies. Based on previous research, BBR significantly reduced levels of fasting blood glucose, hemoglobin A1C, inflammatory cytokines, and oxidative stress markers. Furthermore, BBR stimulated insulin secretion and improved insulin resistance through different pathways, including up-regulation of protein expression of proliferator-activated receptor (PPAR)-γ, glucose transporter (GLUT) 4, PI3K/AKT, and AMP-activated protein kinase (AMPK) activation. Interestingly, it was demonstrated that BBR has protective effects against diabetes complications, such as diabetic-induced hepatic damage, cardiovascular disorders, nephropathy, and neuropathy. Furthermore, multiple clinical trial studies have emphasized the ameliorative effects of BBR in type 2 diabetic patients.

Berberine ameliorates the neurological dysfunction of the gastric fundus by promoting calcium channels dependent release of ACh in STZ-induced diabetic rats

Background

It has been reported diabetic gastroparesis is related to diabetic autonomic neuropathy of the gastrointestinal tract, and berberine (BBR) could ameliorate diabetic central and peripheral neuropathy. However, the influence of BBR on the function and motility of the gastric fundus nerve is unclear.

Methods

A diabetic rat model was constructed, and HE staining was used to observe the morphological changes in the gastric fundus. The changes in cholinergic and nitrogen-related neurochemical indexes and the effects of BBR on them were measured using Elisa. The effects of BBR on the neural function and motility of gastric fundus were investigated by electric field stimulation (EFS) induced neurogenic response in vitro.

Results

In the early stage of STZ-induced diabetic rats, the contractile response of gastric fundus induced by EFS was disorder, disturbance of contraction amplitude, and the cell bodies of neurons in the myenteric plexus of gastric fundus presented vacuolar lesions. Administration with BBR could improve the above symptoms. BBR further enhanced the contraction response in the presence of a NOS inhibitor or the case of inhibitory neurotransmitters removal. Interestingly, the activity of ACh could affect NO release directly and the enhancement of BBR on contractile response was canceled by calcium channel blockers completely.

Conclusions

In the early stage of STZ-induced diabetic rats, the neurogenic contractile response disorder of the gastric fundus is mainly related to cholinergic and nitrergic nerve dysfunction. BBR promotes the release of ACh mainly by affecting the calcium channel to improve the neurological dysfunction of the gastric fundus.

Oxidative Regulation of Vascular Cav1.2 Channels Triggers Vascular Dysfunction in Hypertension-Related Disorders

Blood pressure is determined by cardiac output and peripheral vascular resistance. The L-type voltage-gated Ca²⁺ (Ca_v1.2) channel in small arteries and arterioles plays an essential role in regulating Ca²⁺ influx, vascular resistance, and blood pressure. Hypertension and preeclampsia are characterized by high blood pressure. In addition, diabetes has a high prevalence of hypertension. The etiology of these disorders remains elusive, involving the complex interplay of environmental and genetic factors. Common to these disorders are oxidative stress and vascular dysfunction. Reactive oxygen species (ROS) derived from NADPH oxidases (NOXs) and mitochondria are primary sources of vascular oxidative stress, whereas dysfunction of the Ca_v1.2 channel confers increased vascular resistance in hypertension. This review will discuss the importance of ROS derived from NOXs and mitochondria in regulating vascular Ca_v1.2 and potential roles of ROS-mediated Ca_v1.2 dysfunction in aberrant vascular function in hypertension, diabetes, and preeclampsia.

Vascular smooth muscle cell dysfunction in neurodegeneration

Vascular smooth muscle cells (VSMCs) are the key moderators of cerebrovascular dynamics in response to the brain's oxygen and nutrient demands. Crucially, VSMCs may provide a sensitive biomarker for neurodegenerative pathologies where vasculature is compromised. An increasing body of research suggests that VSMCs have remarkable plasticity and their pathophysiology may play a key role in the complex process of neurodegeneration. Furthermore, extrinsic risk factors, including environmental conditions and traumatic events can impact vascular function through changes in VSMC morphology. VSMC dysfunction can be characterised at the molecular level both preclinically, and clinically ex vivo. However the identification of VSMC dysfunction in living individuals is important to understand changes in vascular function at the onset and progression of neurological disorders such as dementia, Alzheimer's disease, and Parkinson's disease. A promising technique to identify changes in the state of cerebral smooth muscle is cerebrovascular reactivity (CVR) which reflects the intrinsic dynamic response of blood vessels in the brain to vasoactive stimuli in order to modulate regional cerebral blood flow (CBF). In this work, we review the role of VSMCs in the most common neurodegenerative disorders and identify physiological systems that may contribute to VSMC dysfunction. The evidence collected here identifies VSMC dysfunction as a strong candidate for novel therapeutics to combat the development and progression of neurodegeneration, and highlights the need for more research on the role of VSMCs and cerebrovascular dynamics in healthy and diseased states.

Berberine: A Review of its Pharmacokinetics Properties and Therapeutic Potentials in Diverse Vascular Diseases

Traditional Chinese medicine plays a significant role in the treatment of various diseases and has attracted increasing attention for clinical applications. Vascular diseases affecting vasculature in the heart, cerebrovascular disease, atherosclerosis, and diabetic complications have compromised quality of life for affected individuals and increase the burden on health care services. Berberine, a naturally occurring isoquinoline alkaloid form Rhizoma coptidis, is widely used in China as a folk medicine for its antibacterial and anti-inflammatory properties. Promisingly, an increasing number of studies have identified several cellular and molecular targets for berberine, indicating its potential as an alternative therapeutic strategy for vascular diseases, as well as providing novel evidence that supports the therapeutic potential of berberine to combat vascular diseases. The purpose of this review is to comprehensively and systematically describe the evidence for berberine as a therapeutic agent in vascular diseases, including its pharmacological effects, molecular mechanisms, and pharmacokinetics. According to data published so far, berberine shows remarkable anti-inflammatory, antioxidant, antiapoptotic, and antiautophagic activity via the regulation of multiple signaling pathways, including AMP-activated protein kinase (AMPK), nuclear factor κB (NF-κB), mitogen-activated protein kinase silent information regulator 1 (SIRT-1), hypoxia-inducible factor 1α (HIF-1α), vascular endothelial growth factor phosphoinositide 3-kinase (PI3K), protein kinase B (Akt), janus kinase 2 (JAK-2), Ca²⁺ channels, and endoplasmic reticulum stress. Moreover, we discuss the existing limitations of berberine in the treatment of vascular diseases, and give corresponding measures. In addition, we propose some research perspectives and challenges, and provide a solid evidence base from which further studies can excavate novel effective drugs from Chinese medicine monomers.

An inhibitory effect of Berberine from herbal Coptis chinensis Franch on rat detrusor contraction in benign prostatic hyperplasia associated with lower urinary tract symptoms

ETHNOPHARMACOLOGICAL RELEVANCE

Coptis chinensis Franch (CCF), also known as Huang Lian in China, is a traditional Chinese medicine that commonly used for more than 2000 years. Clinically, CCF often used as anti-inflammatory, immune regulation and other effects. It has been reported that the decoction containing CCF can be used for the treatment of benign prostatic hyperplasia (BPH) or lower urinary tract symptoms (LUTS).

AIM OF THE STUDY

This research aims to investigate the effect of CCF on inhibition of BPH development in vivo and in vitro, and further identify the active compound (s) and the possible mechanism involved in BPH-related bladder dysfunction.

MATERIALS AND METHODS

Oestrodial/testosterone-induced BPH rat model was established as the in vivo model. The prostate index (PI) was calculated, the pathogenesis was analyzed and the micturition parameters were determined in the shamed-operated, BPH model and BPH + CCF groups after 4-week administration. The tension in detrusor strips was then assessed upon KCl or ACh stimulation with or without incubation of CCF or active compounds. To further investigate the signaling involved, rat detrusor cells were cultured as the in vitro models, the instantaneous calcium influx was measured and the ROCK-1 expression was detected.

RESULTS

Increased PI value and the aggravated prostatic pathology were observed with voiding dysfunction in BPH rats, which were significantly blocked by oral CCF taken. ACh or KCl-induced contractile responses in detrusor strips were significantly inhibited and the micturition parameters were improved when incubation with CCF or its active compounds such as berberine. Both CCF and berberine suppressed the cellular calcium influx and ROCK-1 expression upon ACh stimulation, demonstrating that berberine was one of the active compounds that contributed to CCF-improved micturition symptoms and function.

CONCLUSIONS

Taken together, our findings give evidence that CCF and its active compound berberine inhibited BPH and bladder dysfunction via Ca²⁺ and ROCK signaling, supporting their clinical use for BPH and BPH-related LUTS treatment.

Biologically active isoquinoline alkaloids covering 2014-2018

Isoquinoline alkaloids, an important class of N-based heterocyclic compounds, have attracted considerable attention from researchers worldwide since the early 19th century. Over the past 200 years, many compounds from this class were isolated, and most of them and their analogs possess various bioactivities. In this review, we survey the updated literature on bioactive alkaloids and highlight research achievements of this alkaloid class during the period of 2014-2018. We reviewed over 400 molecules with a broad range of bioactivities, including antitumor, antidiabetic and its complications, antibacterial, antifungal, antiviral, antiparasitic, insecticidal, anti-inflammatory, antioxidant, neuroprotective, and other activities. This review should provide new indications or directions for the discovery of new and better drugs from the original naturally occurring isoquinoline alkaloids.

Berberine alleviates type 2 diabetic symptoms by altering gut microbiota and reducing aromatic amino acids

OBJECTIVE

Berberine (BBR), which is extracted from traditional Chinese herb, is abundant in Coptis chinensis and Berberis vulgaris, with a treatment on type 2 diabetes mellitus (T2DM). However, its oral bioavailability is poor. Therefore, the ability of BBR to regulate gut microbiota and intestinal metabolites might exist. This study aimed to investigate changes in gut microbiota and intestinal metabolites, and to reveal the potential mechanism of BBR.

METHODS

To observe the role of gut microbiota in the treatment of T2DM by BBR, antibiotics intervened gut microbiota was used in this study, and the therapeutic effects of BBR were evaluated. A 16S rRNA gene sequencing approach was utilized to analyze gut microbiota alterations, and UHPLC-QTOF/MS-based untargeted metabolomics analysis of colon contents was used to identity differential intestinal metabolites. Finally, serum aromatic amino acids (AAAs) were absolutely quantified using LC/MS.

RESULTS

Inhibition of the blood glucose levels, and improvements in glucose tolerance and serum lipid parameters were observed in the BBR treated group. Type 2 diabetic symptoms in rats in the BA group (treated with antibotics and BBR) were alleviated. However, the therapeutical effects are weaker in the BA group compared with the BBR group, indicating that BBR can be used to treat type 2 diabetic rats immediately, and modulation of gut microbiota is related to the mechanism of BBR in the treatment of T2DM. The community richness and diversity of the gut microbiota were significantly increased by BBR, and the relative abundance of Bacteroidetes was increased in the BBR group, which was accompanied by a decreased relative abundance of Proteobacteria and Verrucomicrobia at the phylum level. At the family level, a probiotic Lactobacillaceae was significantly upregulated not only in the BBR group but also in the BA group and was negatively associated with the risk of T2DM. Metabolomic analysis of colon contents identified 55 differential intestinal metabolites between the BBR group and the model group. AAAs, including tyrosine, tryptophan and phenylalanine, were obviously decreased in the BBR group not only in the colon contents but also in the serum.

CONCLUSIONS

These results demonstrated that BBR could alleviate symptoms in type 2 diabetic rats by affecting gut microbiota composition and reducing the concentration of AAAs.

Berberine Promotes the Proliferation and Osteogenic Differentiation of Alveolar Osteoblasts through Regulating the Expression of miR-214

INTRODUCTION AND OBJECTIVE

Alveolar osteoblasts have critical functions during alveolar bone regeneration. Berberine (BBR) and microRNAs (miRNAs) are considered to play important roles in regulating osteoblast differentiation. The study aimed to investigate the role and mechanisms of BBR in osteogenic differentiation of human alveolar osteoblasts (HAOBs) and determine miR-214 expression in the process.

METHODS

Healthy human alveolar bones were cultured in vitro and prepared for morphological observation and alkaline phosphatase (ALP) staining. The third generation of HAOBs was used for cell transfection and treated by different concentrations of BBR. Cell Counting Kit-8 was used to detect the effect of BBR and increased miR-214 on the proliferation of HAOBs. qRT-PCR and Western blot were used to detect the expression of osteogenic differentiation-related genes and miR-214 level, respectively.

RESULTS

The ALP staining results were positive, indicating that cultured cells were HAOBs. Different concentrations of BBR significantly promoted the proliferation of HAOBs and increased the expression levels of ALP, osteocalcin (OCN), collagen type I alpha 1 (COL1A1), runt related transcription factor 2 (RUNX2), and osterix (OSX). Moreover, the expression of miR-214 was reduced as BBR concentrations increased, and the increase of miR-214 reversed the BBR-induced proliferation and osteogenic differentiation of HAOBs.

CONCLUSION

BBR could promote the proliferation and osteogenic differentiation of HAOBs through downregulating the expression of miR-214.

Berberine: A Plant-derived Alkaloid with Therapeutic Potential to Combat Alzheimer's disease

Berberine (a protoberberine isoquinoline alkaloid) has shown promising pharmacological activities, including analgesic, anti-inflammatory, anticancer, antidiabetic, anti-hyperlipidemic, cardioprotective, memory enhancement, antidepressant, antioxidant, anti-nociceptive, antimicrobial, anti- HIV and cholesterol-lowering effects. It is used in the treatment of the neurodegenerative disorder. It has strong evidence to serve as a potent phytoconstituent in the treatment of various neurodegenerative disorders such as AD. It limits the extracellular amyloid plaques and intracellular neurofibrillary tangles. It has also lipid-glucose lowering ability, hence can be used as a protective agent in atherosclerosis and AD. However, more detailed investigations along with safety assessment of berberine are warranted to clarify its role in limiting various risk factors and AD-related pathologies. This review highlights the pharmacological basis to control oxidative stress, neuroinflammation and protective effect of berberine in AD, which will benefit to the biological scientists in understanding and exploring the new vistas of berberine in combating Alzheimer's disease.

Berberine for prevention of dementia associated with diabetes and its comorbidities: A systematic review

BACKGROUND

A growing number of epidemiological studies indicate that metabolic syndrome (MetS) and its associated features play a key role in the development of certain degenerative brain disorders, including Alzheimer's disease and vascular dementia. Produced by several different medicinal plants, berberine is a bioactive alkaloid with a wide range of pharmacological effects, including antidiabetic effects. However, it is not clear whether berberine could prevent the development of dementia in association with diabetes.

OBJECTIVE

To give an overview of the therapeutic potential of berberine as a treatment for dementia associated with diabetes.

SEARCH STRATEGY

Database searches A and B were conducted using PubMed and ScienceDirect. In search A, studies on berberine's antidementia activities were identified using "berberine" and "dementia" as search terms. In search B, recent studies on berberine's effects on diabetes were surveyed using "berberine" and "diabetes" as search terms.

INCLUSION CRITERIA

Clinical and preclinical studies that investigated berberine's effects associated with MetS and cognitive dysfunction were included.

DATA EXTRACTION AND ANALYSIS

Data from studies were extracted by one author, and checked by a second; quality assessments were performed independently by two authors.

RESULTS

In search A, 61 articles were identified, and 22 original research articles were selected. In search B, 458 articles were identified, of which 101 were deemed relevant and selected. Three duplicates were removed, and a total of 120 articles were reviewed for this study. The results demonstrate that berberine exerts beneficial effects directly in the brain: enhancing cholinergic neurotransmission, improving cerebral blood flow, protecting neurons from inflammation, limiting hyperphosphorylation of tau and facilitating β-amyloid peptide clearance. In addition, evidence is growing that berberine is effective against diabetes and associated disorders, such as atherosclerosis, cardiomyopathy, hypertension, hepatic steatosis, diabetic nephropathy, gut dysbiosis, retinopathy and neuropathy, suggesting indirect benefits for the prevention of dementia.

CONCLUSION

Berberine could impede the development of dementia via multiple mechanisms: preventing brain damages and enhancing cognition directly in the brain, and indirectly through alleviating risk factors such as metabolic dysfunction, and cardiovascular, kidney and liver diseases. This study provided evidence to support the value of berberine in the prevention of dementia associated with MetS.

BMAL1 Disrupted Intrinsic Diurnal Oscillation in Rat Cerebrovascular Contractility of Simulated Microgravity Rats by Altering Circadian Regulation of miR-103/CaV1.2 Signal Pathway

The functional and structural adaptations in cerebral arteries could be one of the fundamental causes in the occurrence of orthostatic intolerance after space flight. In addition, emerging studies have found that many cardiovascular functions exhibit circadian rhythm. Several lines of evidence suggest that space flight might increase an astronaut’s cardiovascular risks by disrupting circadian rhythm. However, it remains unknown whether microgravity disrupts the diurnal variation in vascular contractility and whether microgravity impacts on circadian clock system. Sprague-Dawley rats were subjected to 28-day hindlimb-unweighting to simulate the effects of microgravity on vasculature. Cerebrovascular contractility was estimated by investigating vasoconstrictor responsiveness and myogenic tone. The circadian regulation of Ca_V1.2 channel was determined by recording whole-cell currents, evaluating protein and mRNA expressions. Then the candidate miRNA in relation with Ca²⁺ signal was screened. Lastly, the underlying pathway involved in circadian regulation of cerebrovascular contractility was determined. The major findings of this study are: (1) The clock gene BMAL1 could induce the expression of miR-103, and in turn modulate the circadian regulation of Ca_V1.2 channel in rat cerebral arteries at post-transcriptional level; and (2) simulated microgravity disrupted intrinsic diurnal oscillation in rat cerebrovascular contractility by altering circadian regulation of BMAL1/miR-103/Ca_V1.2 signal pathway.

Comparison of cerebral and cutaneous microvascular dysfunction with the development of type 1 diabetes

Rationale: Diabetes can lead to cerebral and cutaneous vascular dysfunction. However, it is still unclear how vascular function changes with the development of diabetes and what differences exist between cerebral and cutaneous vascular dysfunction. Thus, it is very important to monitor changes in cerebral and cutaneous vascular function responses in vivo and study their differences during diabetes development. Methods: With the assistance of newly developed skull and skin optical clearing techniques, we monitored the responses of sodium nitroprusside (SNP)- and acetyl choline (ACh)-induced cerebral and cutaneous vascular blood flow and blood oxygen in diabetic mice in vivo during the development of type 1 diabetes (T1D) by combining laser speckle contrast imaging with hyperspectral imaging. We then compared the differences between cerebral and cutaneous vascular responses and explored the reasons for abnormal changes induced in response to different vascular beds. Results: In the early stage of diabetes (T1D-1 week), there were abnormal changes in the cerebral vascular blood flow and blood oxygen responses to SNP and ACh as well as cutaneous vascular blood oxygen. The cutaneous vascular blood flow response also became abnormal from T1D-3 weeks. Additionally, the T1D-induced abnormal blood flow response was associated with changes in vascular myosin light chain phosphorylation and muscarinic acetylcholine receptor M3 levels, and the aberrant blood oxygen response was related to an increase in glycated hemoglobin levels. Conclusion: These results suggest that the abnormal cutaneous vascular blood oxygen response occurred earlier than the blood flow response and therefore has the potential to serve as a good assessment indicator for revealing cerebrovascular dysfunction in the early stage of diabetes.

Rhizoma coptidis as a Potential Treatment Agent for Type 2 Diabetes Mellitus and the Underlying Mechanisms: A Review

Diabetes mellitus, especially type 2 diabetes mellitus (T2DM), has become a significant public health burden. Rhizoma coptidis (RC), known as Huang Lian, is widely used for treating diabetes in China. The bioactive compounds of RC, especially alkaloids, have the potential to suppress T2DM-induced lesions, including diabetic vascular dysfunction, diabetic heart disease, diabetic hyperlipidemia, diabetic nephropathy, diabetic encephalopathy, diabetic osteopathy, diabetic enteropathy, and diabetic retinopathy. This review summarizes the effects of RC and its bioactive compounds on T2DM and T2DM complications. Less research has been conducted on non-alkaloid fractions of RC, which may exert synergistic action with alkaloids. Moreover, we summarized the pharmacokinetic properties and structure-activity relationships of RC on T2DM with reference to extant literature and showed clearly that RC has potential therapeutic effect on T2DM.

Panaxadiol inhibits synaptic dysfunction in Alzheimer's disease and targets the Fyn protein in APP/PS1 mice and APP-SH-SY5Y cells

AIM

Alzheimer's disease (AD), a neurodegenerative disease, is characterized by memory loss and synaptic damage. Up to now, there are limited drugs to cure or delay the state of this illness. Recently, the Fyn tyrosine kinase is implicated in AD pathology triggered by synaptic damage. Thus, Fyn inhibition may prevent or delay the AD progression. Therefore, in this paper, we investigated whether Panaxadiol could decrease synaptic damage in AD and the underlying mechanism.

MAIN METHODS

The ability of learning and memory of mice has detected by Morris Water Maze. The pathological changes detected by H&E staining and Nissl staining. The percentage of cell apoptosis and the calcium concentration were detected by Flow Cytometry in vitro. The amount of synaptic protein and related proteins in the Fyn/GluN2B/CaMKIIα signaling pathway were detected by Western Blot.

KEY FINDINGS

In the present article, Panaxadiol could significantly improve the ability of learning and memory of mice and reduce its synaptic dysfunction. Panaxadiol could down-regulate GluN2B's phosphorylation level by inhibition Fyn kinase activity, Subsequently, decrease Ca²⁺-mediated synaptic damage, reducing LDH leakage, inhibiting apoptosis in AD, resulting in facilitating the cells survival. For the underlying molecular mechanism, we used PP2 to block the Fyn/GluN2B/CaMKIIα signaling pathway. The results from WB showed that the expression of related proteins in the Fyn signaling pathway decreased with PP2 treated.

SIGNIFICANCE

Our results indicate that Panaxadiol could decrease synaptic damage, which will cause AD via inhibition of the Fyn/GluN2B/CaMKIIα signaling pathway. Thus, the Panaxadiol is a best promising candidate to test as a potential therapy for AD.

Evaluation of type 2 diabetic mellitus animal models via interactions between insulin and mitogen‑activated protein kinase signaling pathways induced by a high fat and sugar diet and streptozotocin

Type 2 diabetic mellitus (T2DM), which is characterized by insulin resistance (IR), hyperglycemia and hyperlipidemia, is a comprehensive dysfunction of metabolism. The insulin receptor (INSR)/phosphoinositide 3‑kinase (PI3K)/AKT signaling pathway is well acknowledged as a predominant pathway associated with glucose uptake; however, the effect of streptozotocin (STZ) plus a high fat and sugar diet (HFSD) on the proteins associated with this pathway requires further elucidation. In order to explore this effect, a T2DM rat model was constructed to investigate T2DM pathogenesis and potential therapeutic advantages. Rats were randomly divided into control and model groups, including normal diet (ND) and HFSD types. ND types were administered intraperitoneal (IP) injections of STZ (35 mg/kg) or a combination of STZ and alloxan monohydrate (AON) (40 mg/kg), whereas HFSD types were composed of HFSD pre‑given, post‑given and simul‑given groups, and were modeled as follows: IP or intramuscular (IM) injection of STZ (35 mg/kg) or a combination of STZ and AON (40 mg/kg). Results indicated that, compared with controls, blood glucose, insulin, homeostatic model assessment‑insulin resistance and total triglyceride were significantly elevated in groups with HFSD and modeling agents (P<0.05 or P<0.01), whereas total cholesterol and low‑density lipoprotein levels were significantly elevated in groups simultaneously administered HFSD and modeling agents (P<0.05 or P<0.01), in addition to downregulation of the expression of insulin signaling pathway proteins in the liver, including INSR, PI3K, AKT1, phosphatidylinositol-5-phosphate 4‑kinase type‑2α (PIP5Kα) and glucose transporter (GLUT)2, and increased expression of inflammatory factors, including p38, tumor necrosis factor (TNF)α and interleukin (IL)6. Furthermore, compared with other two HFSD types including pre‑given and post‑given group, the simul‑given group that received IM injection with STZ exhibited decreased expression levels of major insulin signal pathway proteins INSR, PI3K, AKT1, PIP5Kα, GLUT2 or GLUT4 in the liver and pancreas (P<0.05 or P<0.01), whereas the opposite was observed in the skeletal muscle. In addition, the protein expression levels of phosphorylated‑p38, p38, IL6 and TNFα in the simul‑given group that received IM injection with STZ were increased (P<0.05 or P<0.01), and histopathology also indicated inflammation in pancreas and liver. The present findings suggest that a low dose of STZ may partially impair the β cells of the pancreas, whereas long‑term excess intake of HFSD may increase lipid metabolites, inhibit the insulin signaling pathway and activate the mitogen‑activated protein kinase p38 signaling pathway. The combined action of STZ and AON may result in insulin resistance, which ultimately results in abnormalities in glucose and lipid metabolism. The present model, analogue to T2DM onset of humans, evaluated the medical effect on metabolic dysfunction and provides an insight into the underlining mechanism of IR.

Berberine reduced blood pressure and improved vasodilation in diabetic rats

Hyperglycemia and hypertension are considered to be the two leading risk factors for vascular disease in diabetic patients. However, few pharmacologic agents could provide a combinational therapy for controlling hyperglycemia and hypertension at the same time in diabetes. The objectives of this study are to investigate whether berberine treatment could directly reduce blood pressure and identify the molecular mechanism underlying the vascular protection of berberine in diabetic rats. Berberine was intragastrically administered with different dosages of 50, 100 and 200 mg/kg/day to diabetic rats for 8 weeks since the injection of streptozotocin. The endothelium-dependent/-independent relaxation in middle cerebral arteries was investigated. The activity of large-conductance Ca²⁺-activated K⁺ channel (BK_Ca) was investigated by recording whole-cell currents, analyzing single-channel activities and assessing the expressions of α- and β1-subunit at protein or mRNA levels. Results of the study suggest that chronic administration of 100 mg/kg/day berberine not only lowered blood glucose but also reduced blood pressure and improved vasodilation in diabetic rats. Furthermore, berberine markedly increased the function and expression of BK_Ca β1-subunit in cerebral vascular smooth muscle cells (VSMCs) isolated from diabetic rats or when exposed to hyperglycemia condition. The present study provided initial evidences that berberine reduced blood pressure and improved vasodilation in diabetic rats by activation of BK_Ca channel in VSMCs, which suggested that berberine might provide a combinational therapy for controlling hyperglycemia and blood pressure in diabetes. Furthermore, our work indicated that activation of BK_Ca channel might be the underlying mechanism responsible for the vascular protection of berberine in diabetes.

Berberine and cinnamaldehyde together prevent lung carcinogenesis

Starving tumor cells by restricting nutrient sources is a promising strategy for combating cancer. Because both berberine and cinnamaldehyde can activate AMP-activated protein kinase (AMPK, a sensor of cellular energy status), we investigated whether the combination of berberine and cinnamaldehyde could synergistically prevent lung carcinogenesis through tumor cell starvation. Urethane treatment induced lung carcinogenesis in mice, downregulated AMPK and mammalian target of rapamycin (mTOR) while upregulating aquaporin-1 (AQP-1) and nuclear factor kappa B (NF-κB). Together, berberine and cinnamaldehyde reduced mouse susceptibility to urethane-induced lung carcinogenesis, and reversed the urethane-induced AMPK, mTOR, AQP-1, and NF-κB expression patterns. In vitro, berberine and cinnamaldehyde together induced A549 cell apoptosis, prevented cell proliferation, autophagy, and wound healing, upregulated AMPK, and downregulated AQP-1. The effects of the combined treatment were reduced by rapamycin (a mTOR inhibitor) or HgCL₂ (an AQP inhibitor), but not Z-VAD-FMK (a caspase inhibitor). The berberine/cinnamaldehyde combination also prevented A549 cell substance permeability and decreased intracellular ATP concentrations. These results suggest the combination of berberine and cinnamaldehyde limited both primary and adaptive nutrient acquisition by lung tumors via AMPK-reduced AQP-1 expression, which ultimately starved the tumor cells.

Salidroside contributes to reducing blood pressure and alleviating cerebrovascular contractile activity in diabetic Goto-Kakizaki Rats by inhibition of L-type calcium channel in smooth muscle cells

BACKGROUND

Vascular disease is a common and often severe complication in diabetes mellitus. Hyperglycemia and hypertension are considered to be two of the leading risk factors for vascular complications in diabetic patients. However, few pharmacologic agents could provide a combinational therapy for controlling hyperglycemia and blood pressure in diabetic patients at the same time. Salidroside (SAL) is the major active ingredient derived from Rhodiola. Recently, it has been reported that SAL have an obvious hypoglycemic effect in diabetes and show a beneficial activity in diabetic vascular dysfunction. However, it remains unknown whether or not SAL treatment could directly reduce blood pressure in diabetes. Furthermore, it is not clear what is the molecular mechanism underlying the vascular protection of SAL treatment in diabetes.

METHODS

Male diabetic Goto-Kakizaki (GK) and non-diabetic control Wistar-Kyoto (WKY) rats were administrated with different dosages of SAL (50, 100 and 200 mg/kg/day) for 4 weeks. Contractile responsiveness of cerebral artery to KCl or 5-HT was investigated by Pressure Myograph System. The activity of Ca_L channel was investigated by recording whole-cell currents, assessing the expressions of Ca_L channel α_1C-subunit and its downstream kinase, MLCK, at protein or mRNA levels.

RESULTS

We showed that administration of 100 mg/kg/day SAL for 4 weeks not only lowered blood glucose, but also reduced blood pressure and alleviated cerebrovascular contractile activity in diabetic GK rats, which suggested that SAL treatment may provide a combinational therapy for lowering blood glucose and reducing blood pressure in diabetes at the same time. Furthermore, SAL treatment markedly inhibited the function and expression of Ca_L channel in cerebral VSMCs isolated from diabetic GK rats or when exposed to hyperglycemia condition, which may be the underlying mechanism responsible for the vascular protection of SAL in diabetes.

CONCLUSIONS

The present study provided evidences that SAL contributes to reducing blood pressure and alleviating cerebrovascular contractile activity in diabetic GK rats by inhibition of Ca_L channel in smooth muscle cells, which may provide a novel approach to treat vascular complications in diabetic patients.

Role of berberine in Alzheimer's disease

Berberine, an important protoberberine isoquinoline alkaloid, has several pharmacological activities, including antimicrobial, glucose- and cholesterol-lowering, antitumoral, and immunomodulatory properties. Substantial studies suggest that berberine may be beneficial to Alzheimer's disease (AD) by limiting the pathogenesis of extracellular amyloid plaques and intracellular neurofibrillary tangles. Increasing evidence has indicated that berberine exerts a protective role in atherosclerosis related to lipid- and glucose-lowering properties, implicating that berberine has the potential to inhibit these risk factors for AD. This review also attempts to discuss the pharmacological basis through which berberine may retard oxidative stress and neuroinflammation to exhibit its protective role in AD. Accordingly, berberine might be considered a potential therapeutic approach to prevent or delay the process of AD. However, more detailed investigations along with a safety assessment of berberine are warranted to clarify the role of berberine in limiting these risk factors and AD-related pathologies.