Gastric emptying, plasma ghrelin and autonomic nerve activity in diabetic rats

Molecular Mechanisms of Hawthorn Extracts in Multiple Organs Disorders in Underlying of Diabetes: A Review

Diabetes mellitus (DM) is one of the most important metabolic disorders associated with chronic hyperglycemia and occurs when the body cannot manage insulin secretion, insulin action, or both. Autoimmune destruction of pancreatic beta cells and insulin resistance are the major pathophysiological factors of types 1 and 2 of DM, respectively. Prolonged hyperglycemia leads to multiple organs dysfunctions, including nephropathy, neuropathy, cardiomyopathy, gastropathy, and micro- and macrovascular disorders. The basis of the metabolic abnormalities in carbohydrate, fat, and protein in diabetes is insufficient action of insulin on various target tissues. Medicinal plants are rich sources of bioactive chemical compounds with therapeutic effects. The beneficial effects of leaves, fruits, and flowers extracts of Crataegus oxyacantha, commonly called hawthorn, belonging to the Rosaceae family, are widely used as hawthorn-derived medicines. Data in this review have been collected from the scientific articles published in databases such as Science Direct, Scopus, PubMed, Web of Science, and Scientific Information Database from 2000 to 2021. Based on this review, hawthorn extracts appear both therapeutic and protective effects against diabetic-related complications in various organs through molecular mechanisms, such as decreasing triglyceride, cholesterol, very low density lipoprotein and increasing the antioxidant activity of superoxide dismutase, catalase, glutathione peroxidase, total antioxidant capacity, decreasing malondialdehyde level, and attenuating tumor necrosis factor alpha, interleukin 6 and sirtuin 1/AMP-activated protein kinase (AMPK)/nuclear factor kappa B (NF-κB) pathway and increasing the phosphorylation of glucose transporter 4, insulin receptor substrate 1, AKT and phosphoinositide 3-kinases, and attenuating blood sugar and regulation of insulin secretion, insulin resistance, and improvement of histopathological changes in pancreatic beta cells. Collectively, hawthorn can be considered as one new target for the research and development of innovative drugs for the prevention or treatment of DM and related problems.

Decreased L-type calcium current in antral smooth muscle cells of STZ-induced diabetic rats

BACKGROUND

Diabetic gastroparesis (delayed gastric emptying) is associated with antral hypomotility. L-type Ca(2+) channels play an important role in generation of action potentials and activation of contractions. This study was designed to investigate if the function of the L-type Ca(2+) channels of antral circular smooth muscle cells (SMCs) is impaired in streptozotocin (STZ)-induced diabetic rats.

METHODS

Eight weeks after the injection of STZ or vehicle, whole-cell patch clamp was used to record Ca(2+) currents, and isometric tension recording was used to measure Ca(2+) influx-induced contractions in circular muscle strips. Solid gastric emptying was measured in diabetic and control rats. Protein expression of Ca(2+) αlC-subunit in antral smooth muscles was compared between diabetic and control rats.

KEY RESULTS

(1) Solid gastric emptying, independent of age or bodyweight, was slower in the diabetic rats, even after acute correction of hyperglycemia. (2) Verapamil, a potent calcium channel blocker, dose dependently reduced solid gastric emptying in normal rats. (3) Current density of L-type Ca(2+) channel at 10 mV in antral circular SMCs was significantly decreased in the diabetic rats (-9.8 ± 0.7 pA/pF vs -15.9 ± 1.0 pA/pF in control, p < 0.001). However, protein expression of the Ca(2+) channel in antral muscles did not differ between diabetic and control rats. (4) Contractile responses to 1 and 3 mM [Ca(2+) ] were significantly reduced in the diabetic antral circular muscle strips, indicative of reduced Ca(2+) influx.

CONCLUSIONS & INFERENCES

These data suggested that the decreased L-type Ca(2+) current in antral SMCs may contribute to antral hypomotility in STZ-induced diabetic rats.