Aims/Hypothesis. To assess the effects of diabetes-induced activation of protein kinase C (PKC) on voltage-dependent and voltage-independent Ca 2+ influx pathways in retinal microvascular smooth muscle cells. Methods. Cytosolic Ca 2+ was estimated in freshly isolated rat retinal arterioles from streptozotocin-induced diabetic and non-diabetic rats using fura-2 microfluorimetry. Voltage-dependent Ca 2+ influx was tested by measuring rises in [Ca 2+ ] i with KCl (100 mmol/l) and store-operated Ca 2+ influx was assessed by depleting [Ca 2+ ] i stores with Ca 2+ free medium containing 5 µmol/l cyclopiazonic acid over 10 min and subsequently measuring the rate of rise in Ca 2+ on adding 2 mmol/l or 10 mmol/l Ca 2+ solution. Results. Ca 2+ entry through voltage-dependent L-type Ca 2+ channels was unaffected by diabetes. In contrast, store-operated Ca 2+ influx was attenuated. In microvessels from non-diabetic rats 20 mmol/l D-mannitol had no effect on store-operated Ca 2+ influx. Diabetic rats injected daily with insulin had store-operated Ca 2+ influx rates similar to non-diabetic control rats. The reduced Ca 2+ entry in diabetic microvessels was reversed by 2-h exposure to 100 nmol/l staurosporine, a non-specific PKC antagonist and was mimicked in microvessels from non-diabetic rats by 10-min exposure to the PKC activator phorbol myristate acetate (100 nmol/l). The specific PKCβ antagonist LY379196 (100 nmol/l) also reversed the poor Ca 2+ influx although its action was less efficacious than staurosporine. Conclusion/interpretation. These results show that store-operated Ca 2+ influx is inhibited in retinal arterioles from rats having sustained increased blood glucose and that PKCβ seems to play a role in mediating this effect. [Diabetologia (2003) Diabetic retinopathy is the most widespread complication of diabetes mellitus and is a major cause of blindness in the working population of developed countries. While the exact pathogenic basis of this condition remains ill-defined, it is clear that hyperglycaemia is a critical factor in its aetiology [1,2]. An early effect of hyperglycaemia is a persistent dilatation of the retinal arterioles which increases ocular blood flow and leads to downstream capillary hypertension. This is thought to contribute directly to the development and progression of the disease [3,4,5]. The angiopathy which then develops is characterised by structural changes such as pericyte [6] and arteriolar

Free fatty acid receptor 2 (FFAR2, also known as GPR43) is a G-protein-coupled receptor activated by short-chain fatty acids that are produced by gut microbiota through fermentation of nondigestible carbohydrates. FFAR2 functions as a metabolic sensor and is expressed in metabolically active tissues, such as adipose tissue. Earlier studies proved the connection between FFAR2 and adipocyte differentiation in mice. The aim of this study was to investigate the implication of FFAR2 receptor in adipogenesis in human chorion-derived mesenchymal stem cells (cMSCs). The short-chain fatty acid, propionate, and phenylacetamide a selective FFAR2 agonist resulted in a marked suppression of lipid droplet accumulation during the adipogenic differentiation of cMSCs. Western blot studies revealed that FFAR2 was detectable at any time point of the differentiation period. The direct involvement of FFAR2 in the differentiation into adipocytes was proven by the downregulation of its gene expression in cMSCs by lentiviral messenger RNA (mRNA) silencing transduction particles. Our results showed that a significant suppression in lipid accumulation upon FFAR2 agonist treatments was elicited by FFAR2-silencing. Based on these results we suggest that propionate inhibits the formation of adipocytes from MSCs and acts on adipogenesis predominantly via FFAR2.

Marked differences were shown in the development of the obese-hyperglycemic syndrome in NZO and obob mice. --In NZO mice glucose tolerance decreases continuously with increasing age and body weight. --In obob mice three phases in the development of the obese-hyperglycemic syndrome are differentiated. In the first, dynamic phase glucose tolerance decreases and insulin secretion increases as does body weight. The intermediary or transitional phase, when the animals weigh about 55 g, is characterised by rapidly changing glucose patterns, i. e. an extremely poor glucose tolerance and extremely high serum insulin level is followed by improving glucose tolerance and decreasing insulin levels. In the third, static phase blood sugar values and serum insulin levels have nearly returned to those of the lean littermates. Body weight slowly decreases. The changes in glucose tolerance and serum insulin are parallelled by changes in islet cell morphology. The gluconeogenic capacity is increased during the dynamic and transitional phases, it declines during the static phase. Diffgrences dctns le dgvetoppement de l'obgsitd et de l'hyperglycdmie chez les souris obob et N ZOR~sum~. En 6tudiant le d6veloppement du syndrome ob6sit6-hyperglyc6mie des souris obob et NZO, des dif-f6rences prononc6es ont 6t6 trouv6es entre ces deux souches. --Chez la souris NZO, la tol@ranee au glucose d6eroit progTessivement avee l'augmentation du poids et de l'gge. --Chez la souris obob, on distingue un ddveloppement du syndrome en 3 phases. Dans un premier temps dynamique, la tol6rance au glucose diminue alors que la s6cr@tion d'insulinc et le poids corporel augmentent. La phase intermddiaire ou transitoirc --lorsque les animaux p6scnt environ 55 g --est caraet@risge par un changement rapide de l'allure des courbes de toldrance, c'est k dire qu'une mauvaise tol@rance an glucose avec insulin6mie 6levge cst suivie d'une am61ioration de la tolgrance au glucose et d'une diminution de l'insulin6mie. Duns un troisiSme temps, statique, les taux de glucose sanguin et d'insuline circulantc sent voisins de ceux des souris normales de mSme age. Le poids corporel diminue lentemerit. Les modifications de la tol@rance au glucose et Fin-sulin@mie vent de pair avec des modifications morphologiques des cellules des riots paner@atiques. La glucon@o-g@ngse est accrue dans les phases dynamique et transitoire, mais diminu6e dens la phase statique. Unterschiedliche Entwicklung des Fettsucht-Hypergly-Ic(tmie-Syndroms beg obob and N ZO-Mi~usenZusammenfassung. Ein Vergleich der altcrsbedingten Ver/indcrungen der Glucosetoleranz bei obobund NZO-M/iusen ergab folgende Unterschiede : Die Glucosetoleranz der NZO-M/iuse nimmt mit zunehmendem Alter und K6rpergewicht progressiv ab. Bei obob-Mausen lassen sich eine dynamische (I), einc intermedi/~re (lI) und eine statische (III) Phase unterscheiden. Im Verlauf der Phase I nimmt die Glucosetoleranz ab, die Seruminsulinkonzentrationen und das K6rpergewicht nehmen zu. Zu Beginn der Phase II (K6rpergewicht ca. 55 g) ist die Glucosetoler...