Glucagon-like peptide-1 receptor and proglucagon expression in mouse skin

Exendin-4, a GLP-1 receptor agonist, suppresses diabetic retinopathy in vivo and in vitro

Diabetic retinopathy (DR) is a complication of diabetes and a leading cause of blindness in adults. Studies have shown that glucagon-like peptide-1 (GLP-1) exerts a protective effect on patients with DR. Here, we investigated the protective effects of Exendin-4, a GLP-1 analogue, on DR. We established a high-glucose-induced HREC cell model and an STZ-induced rat DR Model to study the effect of Exendin-4 in DR in vitro and in vivo. The qRT-PCR, CCK-8, TUNEL, western blotting, tube formation assays, and ELISA were performed. In addition, we overexpressed TGFB2 to observe whether the protective effect of Exendin-4 was reversed. Our results showed that Exendin-4 inhibited the progression of DR. Furthermore, the protective effect of Exendin-4 was suppressed in cells overexpressing TGFB2. Our findings suggest that Exendin-4 may be involved in the regulation of TGFB2 expression levels to inhibit DR. These results indicate that Exendin-4 could be an effective therapy for DR.

The role of mast cells in cellular modifications evoked by Exendin-4 in treated wounds: a preclinical study

OBJECTIVE

To assess the response of cellular infiltration in wounds treated with Exendin-4.

METHOD

In this study, 16 mice were used. On each mouse, two wounds were produced, one above the other, in order to study the effects of the various treatments carried out. The wounds then received an intradermal injection of either saline (20μl; Group 1) or Exendin-4 (Exe4, 62ng; Group 2) in the upper and lower wounds, respectively. The mice were euthanised in order to collect the wounds at time of abrasion (T0), at 48 hours (T1), 96 hours (T2) and 144 hours (T3). The expression of the glucagon-like peptide-1 receptor (GLP-1R) was evaluated by Western blot in wound lysates. Histological and histochemistry methods were applied in cryosections.

RESULTS

In T2 and T3 treated wounds, the mast cells degranulation index increased while GLP-1R expression, tumour necrosis factor (TNF)-α, or heat shock protein (HSP)47 antigens were detected in their cytoplasm. These cells interacted with dendritic cells, vessels or granulocytes. The density of dendritic cells increased progressively, and intercellular connections were found between these cells and vessels. Among the dendritic cells at T2, only M2 macrophages increased. However, M1 cells expressed transforming growth factor (TGF)-β and both interacted with either fibroblasts or with vessels. The number of plasmacytoid dendritic cells increased and established close contacts with regulatory T cells.

CONCLUSION

We propose that after treatment with Exe4, early activation of mast cells is critical in wound healing acceleration. This is crucial in understanding the potential effect of this drug for viable clinical therapies.

DECLARATION OF INTEREST

No potential conflict of interest was reported by the authors.

Insight into the role of DPP-4 in fibrotic wound healing

Wound healing is a complex and long-term process consisting of hemostasis, inflammation, proliferation, and maturation/remodeling. These four stages overlap and influence each other; they affect wound healing in different ways, and if they do not function perfectly, they may cause scarring, proliferative scarring and keloid formation. A therapeutic target affecting wound healing in multiple ways will help the healing process proceed more effectively. DPP-4/CD26 is a multifunctional dimorphic glycoprotein widely distributed on the surface of a variety of cells, including fibroblasts and keratin-forming cells. It has been found to affect periwound inflammation, re-epithelialization, extracellular matrix secretion and skin fibrosis and is a potential target for promoting wound healing and inhibiting scar formation. After presenting a brief introduction of the wound healing process and DPP-4/CD26, this paper summarizes the effects of DPP-4/CD26 on cells involved in different stages of wound healing and discusses the feasibility of DPP-4/CD26 as a multifunctional target for the treatment of wound healing and inhibition of scar formation.

An Uncommon Case of Dulaglutide-Related Morbilliform Drug Eruption

Dulaglutide is a once-weekly injectable glucagon-like peptide-1 (GLP-1) receptor agonist that has shown a durable glycemic efficacy as well as beneficial effects on body weight and major adverse cardiovascular events (MACE) outcomes, making it an important option for the treatment of type 2 diabetes. Common side effects of dulaglutide include nausea, diarrhea, and abdominal distension, and these are usually mild to moderate in severity and tend to diminish over time. Morbilliform drug eruptions to dulaglutide are very rare, with only one case reported until now. We report another case of dulaglutide-morbilliform drug eruption to alert the attending physicians that dulaglutide-related adverse skin reactions should be kept in mind as generalized use of dulaglutide and other GLP-1 receptor agonists are expected to remain in widespread clinical use in the future.

Antidiabetic effects of quercetin and liraglutide combination through modulation of TXNIP/IRS-1/PI3K pathway

The study was designed to assess the possible augmented antidiabetic effects of combining quercetin and liraglutide in a type 1 diabetes model, with emphasis on the contribution of hepatic thioredoxin interacting protein (TXNIP)/insulin receptor substrate 1 (IRS-1)/phosphatidyl inositol-3 kinase (PI3K) pathway. The wound-healing effects were also examined. Diabetes was induced by a single i.p STZ injection (55 mg/kg). Diabetic rats were treated with either quercetin (100 mg/kg/day, orally) or liraglutide (0.3 mg/kg/twice daily, S.C.) or their combination. Drugs were also applied topically on the wound. Blood glucose levels, serum albumin, total protein, total cholesterol and triglycerides were measured. Histopathological examination of the liver, pancreas and skin tissues was performed using haematoxylin and eosin staining. The hepatic malondialdehyde level was measured spectrophotometrically. Hepatic TXNIP and PI3K levels were measured by enzyme-linked immunsorbent assay (ELISA). Tissue expression of IRS-1 and phospho-IRS-1 (Ser 616) was assessed by immunohistochemistry. Quercetin, liraglutide and their combination effectively decreased blood glucose levels, improved lipid profile, upregulated albumin and total protein serum levels and reduced hepatic oxidative stress with the combination being most effective. Moreover, the combination group showed enhanced wound-healing effects and almost normalized hepatic and pancreatic histopathology. Quercetin and/or liraglutide significantly decreased TXNIP levels and serine phosphorylation of IRS-1 and increased PI3K levels compared to the diabetic untreated group. Interestingly, only the combination therapy normalized hepatic IRS-1 expression. The combination of quercetin and liraglutide showed enhanced antidiabetic effects, possibly through lowering hepatic TXNIP levels, with the resultant up-regulation of the IRS-1/PI3K pathway.

Glucagon-like peptide-1 analogue liraglutide facilitates wound healing by activating PI3K/Akt pathway in keratinocytes

AIMS

Diabetes induces various skin troubles including foot ulcer. This type of skin ulcer is refractory but the pathogenesis is not so certain. Recent study show that glucagon-like peptide-1 (GLP-1) analogues reduce foot complications with diabetes (Pérez et al., 2015), however, the role of GLP-1/GLP-1R axis is not fully understood, and clear evidence of GLP-1 to facilitate wound closure is still lacking. In this study, we investigated whether a potent GLP-1R agonist liraglutide affects wound healing process.

METHODS

The expression of GLP-1R in HaCaT cells were indentified by quantitative reverse-transcription polymerase chain reaction (qRT-PCR) and immunoblotting analysis. To assess the effect on wound closure in keratinocytes, we performed in vitro scratch assay using the IncuCyte system (Essen BioSciences, Ann Arborm MI). We applied ointment containing liraglutide on full-thickness wounds in the dorsum of female balb/c mice (n = 6) until healing. To investigate the effect on PI3K/Akt pathway, we used IncuCyte system in HaCaT treated with PI3K inhibitor and Akt inhibitor.

RESULTS

Keratinocytes expressed GLP-1R and liraglutide induced their migration. Liraglutide facilitated the wound healing in mice. Liraglutide upregulated keratinocyte migration via PI3K/Akt activation.

CONCLUSIONS

Our study suggests that liraglutide may be a potential target drug to improve skin ulcer with diabetes through its specific receptor GLP-1.

Anti-inflammatory and pro-healing impacts of exendin-4 treatment in Zucker diabetic rats: Effects on skin wound fibroblasts

Using male Zucker diabetic fatty (ZDF) rats implanted subcutaneously with polyethylene mesh pieces stimulating granulation tissue development, we investigated the effects of the in vivo and in vitro treatment with exendin-4, a glucagon-like peptide-1 agonist displaying a variety of antidiabetic actions, on the markers of metabolism, inflammation, and healing in addition to skin wound fibroblast/myofibroblast activities. Exendin-4 at increasing doses of 3-10 μg/kg or 0.9% saline was injected daily to ZDF rats pre-implanted with the mesh for 3 weeks. Then, fibroblasts/myofibroblasts isolated from the granulation tissue in both groups were further exposed in vitro to exendin-4 at concentrations of 0-100 nmol/l. After a 3-week administration period, cumulative food and water intake and body weight were reduced significantly. The serum and fibroblast culture medium C-reactive protein (CRP) concentrations and matrix metalloprotease-9/tissue matrix metalloproteinase inhibitor-1 (MMP-9/TIMP-1) ratio in the fibroblast culture medium were diminished significantly in the exendin-4 pretreated group, indicating the increased expression of anti-inflammatory and pro-healing biomarkers. In vivo exendin-4 treatment also increased the number of living fibroblasts/myofibroblasts in cell cultures. The subsequent in vitro exposure to exendin-4 significantly increased metabolic activity and total collagen content in fibroblast/myofibroblast colonies derived from exendin-4-pretreated rats but reduced the number of viable cells. A cytotoxic effect was noted at the highest exendin-4 concentrations used. To conclude, the treatment of diabetic rats with exendin-4 had beneficial effects on systemic and tissue metabolic, inflammatory, and healing markers and on fibroblast functions crucial for wound repair but showed some cytotoxicity on these cells.

Dissecting the Physiology and Pathophysiology of Glucagon-Like Peptide-1

An aging world population exposed to a sedentary life style is currently plagued by chronic metabolic diseases, such as type-2 diabetes, that are spreading worldwide at an unprecedented rate. One of the most promising pharmacological approaches for the management of type 2 diabetes takes advantage of the peptide hormone glucagon-like peptide-1 (GLP-1) under the form of protease resistant mimetics, and DPP-IV inhibitors. Despite the improved quality of life, long-term treatments with these new classes of drugs are riddled with serious and life-threatening side-effects, with no overall cure of the disease. New evidence is shedding more light over the complex physiology of GLP-1 in health and metabolic diseases. Herein, we discuss the most recent advancements in the biology of gut receptors known to induce the secretion of GLP-1, to bridge the multiple gaps into our understanding of its physiology and pathology.

Bullous pemphigoid and dipeptidyl peptidase IV inhibitors: a case-noncase study in the French Pharmacovigilance Database

BACKGROUND

Inhibitors of dipeptidyl peptidase (DPP)-IV have been suspected in the onset of bullous pemphigoid for several years now. However, comparative studies assessing the link between DPP-IV inhibitor exposure and bullous pemphigoid have not yet been performed.

OBJECTIVES

To detect, from the French Pharmacovigilance Database (FPVD), a signal of risk of bullous pemphigoid during DPP-IV inhibitor exposure by comparative study.

METHODS

All spontaneous reports of DPP-IV inhibitor-related bullous pemphigoid recorded in the FPVD between April 2008 and August 2014 were described. We conducted disproportionality analyses (case-noncase method) to assess the link between DPP-IV inhibitors and bullous pemphigoid, calculating reporting odds ratios (RORs). We also compared DPP-IV inhibitor-induced bullous pemphigoid reports rated per million defined daily doses dispensed during the study period.

RESULTS

Among 217 331 spontaneous adverse drug reaction reports registered in the FPVD, 1297 involved DPP-IV inhibitors. Among these observations, 42 were bullous pemphigoid (vildagliptin, n = 31; sitagliptin, n = 10; saxagliptin, n = 1). The ROR for pooled DPP-IV inhibitors was 67·5 [95% confidence interval (CI) 47·1-96·9]. Disproportionality was also observed for each DPP-IV inhibitor: vildagliptin (ROR 225·3, 95% CI 148·9-340·9), sitagliptin (ROR 17·0, 95% CI 8·9-32·5) and saxagliptin (ROR 16·5, 95% CI 2·3-119·1). Analyses adjusted on dispensing data led to similar results.

CONCLUSIONS

These data confirm a strong signal for an increased risk of bullous pemphigoid during DPP-IV inhibitor exposure. This adverse drug reaction is observed for each DPP-IV inhibitor, suggesting a class effect. The signal was higher with vildagliptin than with the other DPP-IV inhibitors.

Mechanisms for the cardiovascular effects of glucagon-like peptide-1

Over the past three decades, at least 10 hormones secreted by the enteroendocrine cells have been discovered, which directly affect the cardiovascular system through their innate receptors expressed in the heart and blood vessels or through a neural mechanism. Glucagon-like peptide-1 (GLP-1), an important incretin, is perhaps best studied of these gut-derived hormones with important cardiovascular effects. In this review, I have discussed the mechanism of GLP-1 release from the enteroendocrine L-cells and its physiological effects on the cardiovascular system. Current evidence suggests that GLP-1 has positive inotropic and chronotropic effects on the heart and may be important in preserving left ventricular structure and function by direct and indirect mechanisms. The direct effects of GLP-1 in the heart may be mediated through GLP-1R expressed in atria as well as arteries and arterioles in the left ventricle and mainly involve in the activation of multiple pro-survival kinases and enhanced energy utilization. There is also good evidence to support the involvement of a second, yet to be identified, GLP-1 receptor. Further, GLP-1(9-36)amide, which was previously thought to be the inactive metabolite of the active GLP-1(7-36)amide, may also have direct cardioprotective effects. GLP-1's action on GLP-1R expressed in the central nervous system, kidney, vasculature and the pancreas may indirectly contribute to its cardioprotective effects.

Bullous pemphigoid induced by vildagliptin: a report of three cases

To report three cases of bullous pemphigoid in patients treated with vildagliptin. Case 1: An 86-year-old woman presented with bullous pemphigoid after 1 month of treatment with vildagliptin and metformin. After introduction of clobetasol, the symptoms resolved although vildagliptin was continued. However, the skin lesions reappeared 3 months later. Sustained remission was achieved only after definitive withdrawal of vildagliptin. Case 2: A 79-year-old man presented with bullous pemphigoid after 37-month treatment with gliclazide, vildagliptin and metformin. The disease at first responded to clobetasol but 3 months later the lesions reappeared. They finally regressed when the gliptin was discontinued. Case 3: A 77-year-old woman, treated with gliclazide and vildagliptin for 26 months, presented with bullous pemphigoid, which responded well to discontinuation of the gliptin and topical clobetasol. Gliptins are new molecules for treatment of type 2 diabetes mellitus, which have been suspected of implication in bullous pemphigoid. Such cases have been described in the literature (seven with vildagliptin and three with sitagliptin). In nine of these cases, the gliptin was associated with metformin, but the latter had never been considered responsible. The mechanism implicated in the development of bullous pemphigoid has not yet been clearly identified, but may involve a modified immune response or alteration of the antigenic properties of the epidermal basement membrane. These reports support the risk of bullous pemphigoid in patients exposed to gliptins.

Improvement in psoriasis after treatment with the glucagon-like peptide-1 receptor agonist liraglutide

A 59-year old man with moderate and stable psoriasis through 15 years was admitted to our Department with inadequately controlled type 2 diabetes. Treatment was initiated with the glucagon-like peptide-1 receptor (GLP-1R) agonist liraglutide. The patient experienced marked improvement in his psoriasis immediately after the start of liraglutide treatment. Itching stopped within days, scaling was reduced and spots of normal skin emerged. After 3 months, psoriasis was still improving. Excellent glycaemic control and a weight loss of approximately 8 kg over 3 months were moreover obtained. The patient had previously been well controlled in his diabetes without improvement in psoriasis, and the effect of liraglutide on psoriasis started before weight loss occurred. We discuss the possibility of a direct anti-inflammatory effect of liraglutide in psoriasis as well as indirect effects through improvement in comorbidities such as overweight. Randomized clinical trials are needed to reveal whether GLP-1R agonists represent a new therapeutic option for psoriasis.

PSCs and GLP-1R: occurrence in normal pancreas, acute/chronic pancreatitis and effect of their activation by a GLP-1R agonist

There is increasing concern about the development of pancreatitis in patients with diabetes mellitus who received long-term glucagon-like peptide-1 (GLP-1) analog treatment. Its pathogenesis is unknown. The effects of GLP-1 agonists on pancreatic endocrine cells are well studied; however, there is little information on effects on other pancreatic tissues that might be involved in inflammatory processes. Pancreatic stellate cells (PSCs) can have an important role in pancreatitis, secreting various inflammatory cytokines/chemokines, as well as collagen. In this study, we investigated GLP-1R occurrence in normal pancreas, acute pancreatitis (AP)/chronic pancreatitis (CP), and the effects of GLP-1 analog on normal PSCs, their ability to stimulate inflammatory mediator secretion or proliferation. GLP-1 receptor (GLP-1R) expression/localization in normal pancreas and pancreatitis (AP/CP) tissues were evaluated with histological/immunohistochemical analysis. PSCs were isolated from male Wistar rats. GLP-1R expression and effects of GLP-1 analog on activated PSCs was examined with real-time PCR, MTS assays and western blotting. In normal pancreas, pancreatic β cells expressed GLP-1R, with only low expression in acinar cells, whereas in AP or CP, acinar cells, ductal cells and activated PSCs expressed GLP-1R. With activation of normal PSCs, GLP-1R is markedly increased, as is multiple other incretin-related receptors. The GLP-1 analog, liraglutide, did not induce inflammatory genes expression in activated PSCs, but induced proliferation. Liraglutide activated multiple signaling cascades in PSCs, and the extracellular signal-regulated kinase pathway mediated the PSCs proliferation. GLP-1Rs are expressed in normal pancreas and there is marked enhanced expression in AP/CP. GLP-1-agonist induced cell proliferation of activated PSCs without increasing release of inflammatory mediators. These results suggest chronic treatment with GLP-1R agonists could lead to proliferation/chronic activation of PSCs, which may lead to important effects in the pancreas.

The dipeptidyl peptidase-4 inhibitor linagliptin attenuates inflammation and accelerates epithelialization in wounds of diabetic ob/ob mice

In recent years, new and effective therapeutic agents for blood glucose control have been added to standard diabetes therapies: dipeptidyl peptidase-4 (DPP-4) inhibitors, which prolong the bioavailability of the endogenously secreted incretin hormone glucagon-like peptide-1 (GLP-1). Full-thickness excisional wounding was performed in wild-type (C57BL/6J) and diabetic [C57BL/6J-obese/obese (ob/ob)] mice. DPP-4 activity was inhibited by oral administration of linagliptin during healing. Wound tissue was analyzed by using histological, molecular, and biochemical techniques. In healthy mice, DPP-4 was constitutively expressed in the keratinocytes of nonwounded skin. After skin injury, DPP-4 expression declined and was lowest during the most active phase of tissue reassembly. In contrast, in ob/ob mice, we observed increasing levels of DPP-4 at late time points, when delayed tissue repair still occurs. Oral administration of the DPP-4 inhibitor linagliptin strongly reduced DPP-4 activity, stabilized active GLP-1 in chronic wounds, and improved healing in ob/ob mice. At day 10 postwounding, linagliptin-treated ob/ob mice showed largely epithelialized wounds characterized by the absence of neutrophils. In addition, DPP-4 inhibition reduced the expression of the proinflammatory markers cyclooxygenase-2 and macrophage inflammatory protein-2, but enhanced the formation of myofibroblasts in healing wounds from ob/ob mice. Our data suggest a potentially beneficial role of DPP-4 inhibition in diabetes-affected wound healing.

Neuroprotective effect of the glucagon-like peptide-1 receptor agonist, synthetic exendin-4, in streptozotocin-induced diabetic rats

BACKGROUND AND PURPOSE

Glucagon-like peptide-1 (GLP-1) receptors are widely expressed in neural tissues and diminish neuronal degeneration or induce neuronal differentiation. The aim of this study was to investigate the effect of the GLP-1 pathway on peripheral nerves in streptozotocin-induced diabetic rats.

EXPERIMENTAL APPROACH

Diabetic and nondiabetic rats were treated with the GLP-1 receptor agonist, synthetic exendin-4 (i.p., 1 nmol·kg(-1)·day(-1)) or placebo for 24 weeks, and current perception threshold values, cAMP levels and nerve fibre size in the sciatic nerve were measured. We also investigated GLP-1 receptor expression, quantitative changes in PGP9.5-positive intraepidermal nerve fibres and cleaved caspase 3-stained Schwann cells by immunohistochemistry.

KEY RESULTS

GLP-1 receptor expression was detected in the sciatic nerve and skin. After exendin-4 treatment, the increase seen in current perception threshold values at 2000 and 250 Hz in diabetic rats was reduced. Also, the decrease in myelinated fibre size or axon/fibre area ratio in the sciatic nerve and the loss of intraepidermal nerve fibre in the skin of diabetic rats were ameliorated. These responses were closely associated with the attenuation of Schwann cell apoptosis and improvement in the cAMP level in exendin-4-treated diabetic rats, compared with placebo-treated animals.

CONCLUSION AND IMPLICATIONS

Synthetic exendin-4 may prevent peripheral nerve degeneration induced by diabetes in an animal model, supporting the hypothesis that GLP-1 may be useful in peripheral neuropathy. The neuroprotection is probably attributable to GLP-1 receptor activation, antiapoptotic effects and restoration of cAMP content.

GLP-1 signals via ERK in peripheral nerve and prevents nerve dysfunction in diabetic mice

AIM

Glucagon-like peptide-1 (GLP-1) is an incretin hormone that induces glucose-dependent insulin secretion and may have neurotrophic properties. Our aim was to identify the presence and activity of GLP-1 receptors (GLP-1Rs) in peripheral nerve and to assess the impact of GLP-1R agonists on diabetes-induced nerve disorders.

METHODS

Tissues were collected from streptozotocin-diabetic rats. GLP-1R function was assessed by incubating tissues from normal and diabetic rats with GLP-1R agonists and antagonists and measuring induction of ERK1/2 phosphorylation by Western blot. Streptozotocin-diabetic mice were also treated with the GLP-1R agonist exenatide for 8 weeks to assess the impact of GLP-1R signalling on peripheral nerve function and structure.

RESULTS

GLP-1R protein was detected in rat dorsal root ganglia and the neurons and Schwann cells of the sciatic nerve. Protein levels were not affected by streptozotocin-induced diabetes. GLP-1R agonists did not signal via ERK1/2 in sciatic nerve of normal rats. However, GLP-1R agonists significantly increased pERK1/2 levels in sciatic nerves from diabetic rats, indicating that GLP-1Rs are functional in this tissue. Exenatide treatment did not affect blood sugar, insulin levels or paw thermal response latencies in either control or diabetic mice. However, the reductions of motor nerve conduction velocity and paw intraepidermal fibre density seen in diabetic mice were attenuated by exenatide treatment.

CONCLUSIONS

These data show that the peripheral nerve of diabetic rodents exhibits functional GLP-1R and suggest that GLP-1R-mediated ERK-signalling in sciatic nerve of diabetic rodents may protect large motor fibre function and small C fibre structure by a mechanism independent of glycaemic control.

Glucagon-like peptide-1 (GLP-1) receptor agonists, obesity and psoriasis: diabetes meets dermatology

Type 2 diabetes mellitus is characterised by beta cell failure, which frequently develops in the setting of insulin resistance. Inflammation contributes to the pathophysiology of type 2 diabetes by impairing insulin action in peripheral tissues and via reduction of beta cell function. Inflammation may also play an important role in the development of complications that arise in patients with type 2 diabetes. Hence, the anti-inflammatory actions of commonly used glucose-lowering drugs may contribute, indirectly, to their mechanisms of action and therapeutic benefit. Herein we highlight the anti-inflammatory actions of glucagon-like peptide-1 (GLP-1), which exerts direct and indirect actions on immune function. The observations that GLP-1 receptor agonists exert anti-inflammatory actions in preclinical studies, taken together with case reports linking improvements in psoriasis with GLP-1 receptor agonist therapy, illustrates the emerging clinical implications of non-classical anti-inflammatory actions of incretin-based therapeutics.

Drug-induced bullous pemphigoid in diabetes mellitus patients receiving dipeptidyl peptidase-IV inhibitors plus metformin

BACKGROUND

Preclinical data and reports of adverse skin reactions in patients treated with dipeptidyl peptidase-IV inhibitors (gliptins) have increased awareness towards skin-targeting side-effects of these anti-hyperglycaemic drugs. Bullous pemphigoid (BP), sometimes drug-induced, is the most commonly acquired autoimmune blistering dermatosis in western countries, typically a disease of the elderly people with significant morbidity and excess mortality.

OBJECTIVE

To report the development of BP in five diabetics under gliptin (4 vildagliptin, 1 sitagliptin) plus metformin in fixed-dose drug combinations.

CASE REPORTS

From March to August 2010 six out of nine newly diagnosed BP patients in our Department were type 2 diabetics. Five of them were on gliptin plus metformin (three different trade preparations) for 2-13 months prior to BP onset. In all cases BP was controlled after withdrawal of the suspected medication and relatively mild therapeutic interventions. In two cases the eliciting role of the preceding treatment is supported by evidence at the level 'probable/likely' according to the WHO-UMC algorithm.

CONCLUSIONS

This is the first report of drug-induced BP as a group adverse event of the gliptins plus metformin combination therapy for glycaemia control in type 2 diabetes mellitus patients.

Effects of centrally-injected glucagon-like peptide-1 on pilocarpine-induced seizures, anxiety and locomotor and exploratory activity in rat

Glucagon-like peptide-1 (7-36)-amide (GLP-1) is a gut peptide, which exerts significant effects on glucose homeostasis. GLP-1 and GLP-1 receptors are also widely distributed in the central nervous system. In the present study, we aimed to investigate the effects of intracerebroventricularly (i.c.v.)-injected GLP-1 on pilocarpine-induced seizures, anxiety and locomotor and exploratory activity in rat. Rats were pretreated with GLP-1 (1-1000 ng/5 microl; i.c.v.) or saline (5 microl; i.c.v.) 30 min before seizure induction by pilocarpine (2.4 mg/5 microl; i.c.v.) and with GLP-1 (1, 10, 100 ng/5 microl; i.c.v.) or saline (5 microl; i.c.v.) 30 min before the open field test or the elevated plus maze test. GLP-1 did not produce any protective effect against pilocarpine-induced seizures and did not also produce statistically significant differences in the number of squares visited (measure of locomotor activity) or number of rearings (measure of exploratory behaviour), compared to the saline-treated rats in the open field test. On the other hand, GLP-1 (1 ng and 10 ng; i.c.v.) induced an anxiogenic effect, indicated by a decrease in the time spent in open arms, an increase in the time spent in closed arms, and a decrease in the anxiety scores in the elevated plus maze test. Pretreatment with an arginine vasopressin (AVP) V(1) receptor antagonist (125 ng/5 microl; i.c.v.) and L-NAME (100 microg/5 microl and 200 microg/5 microl) significantly abolished the anxiogenic effect of GLP-1 (1 ng/5 microl; i.c.v.). These results suggest that, centrally-injected GLP-1 produces anxiogenic effects via NO pathway and AVP V(1) receptors, but does not have any effects on pilocarpine-induced seizures or locomotor and exploratory activity in the open field test.

Glucagon and glucagon-like peptides 1 and 2

The glucagon gene is expressed not only in the alpha cells of the pancreatic islets but also in the endocrine cells of the intestinal epithelium (so-called L-cells), and in certain neurons of the brain stem. Whereas in the pancreas, glucagon, the hyperglycaemic hormone, is cleaved out of the 160 amino acid precursor, proglucagon, leaving behind proglucagon fragments (PG 1-30 and PG 72-158, the so-called major proglucagon fragment (MPGF)) that are probably inactive, the intestinal processing leads to the formation of glicentin (PG 1-69; action uncertain) and glucagon-like peptides 1 (PG 78-107amide, a potent incretin homone, regulating insulin secretion, glucagon secretion, gastrointestinal motility and appetite) and 2 (PG 126-158, a regulator of gut mucosal growth and integrity). The two prohormone convertases PC2 and PC1/3, respectively, are responsible for the differential processing. After their release, the hormones are eliminated mainly in the kidneys, but both GLP-2 and in particular GLP-1, but not glucagon, are metabolized both locally and in the circulation and liver by dipeptidyl peptidase 4 (DPP-4) which inactivates the peptides, suggesting that GLP-1 acts locally rather than in an endocrine manner. A number of transcription factors have been identified that can at least partly explain the differential cellular expression of the glucagon gene as well as the differential tissue-specific processing of the precursor.

Thirty-five percent oxygen pre-conditioning protects PC12 cells against death induced by hypoxia

The present study is designed to investigate the effect of pre-conditioning with 35% O2 on PC12 cell death induced by hypoxia. This study investigated whether 35% O2 pre-conditioning for 3 h, followed by 12 h recovery, can protect PC12 cells against death induced by subsequent exposure to hypoxia for 72 h. The result showed that pre-conditioning with 35% O2 partly blocked the decrease in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction induced by hypoxia in PC12 cells. PC12 cells pre-conditioned with 35% O2 could generate a small quantity of reactive oxygen species (ROS), which activated the extracellular signal-regulated kinase (ERK) signalling pathway, then the over-expression of the B-cell lymphoma/leukaemia-2 (Bcl-2) was induced, which subsequently protected PC12 cell against death resulting from hypoxia exposure. In conclusion, 35% O2 pre-conditioning could protect PC12 cells against hypoxic insult.