scholarly journals The role of autonomic efferents and uncoupling protein 1 in the glucose-lowering effect of leptin therapy

2016 ◽  
Vol 5 (8) ◽  
pp. 716-724 ◽  
Author(s):  
Heather C. Denroche ◽  
Michelle M. Kwon ◽  
Maria M. Glavas ◽  
Eva Tudurí ◽  
Marion Philippe ◽  
...  
2020 ◽  
Vol 318 (1) ◽  
pp. E72-E86
Author(s):  
Petr Zouhar ◽  
Günaj Rakipovski ◽  
Muhammad Hamza Bokhari ◽  
Oliver Busby ◽  
Johan F. Paulsson ◽  
...  

The possibility to use leptin therapeutically for lowering glucose levels in patients with type 1 diabetes has attracted interest. However, earlier animal models of type 1 diabetes are severely catabolic with very low endogenous leptin levels, unlike most patients with diabetes. Here, we aim to test glucose-lowering effects of leptin in novel, more human-like murine models. We examined the glucose-lowering potential of leptin in diabetic models of two types: streptozotocin-treated mice and mice treated with the insulin receptor antagonist S961. To prevent hypoleptinemia, we used combinations of thermoneutral temperature and high-fat feeding. Leptin fully normalized hyperglycemia in standard chow-fed streptozotocin-treated diabetic mice. However, more humanized physiological conditions (high-fat diets or thermoneutral temperatures) that increased adiposity — and thus also leptin levels — in the diabetic mice abrogated the effects of leptin, i.e., the mice developed leptin resistance also in this respect. The glucose-lowering effect of leptin was not dependent on the presence of the uncoupling protein-1 and was not associated with alterations in plasma insulin, insulin-like growth factor 1, food intake or corticosterone but fully correlated with decreased plasma glucagon levels and gluconeogenesis. An important implication of these observations is that the therapeutic potential of leptin as an additional treatment in patients with type 1 diabetes is probably limited. This is because such patients are treated with insulin and do not display low leptin levels. Thus, the potential for a glucose-lowering effect of leptin would already have been attained with standard insulin therapy, and further effects on blood glucose level through additional leptin cannot be anticipated.


2021 ◽  
Vol 142 ◽  
pp. 110209
Author(s):  
Renata Luise de Araujo ◽  
Francisco A. Tomás-Barberán ◽  
Rosa Ferreira dos Santos ◽  
J. Alberto Martinez-Blazquez ◽  
Maria Inés Genovese

2014 ◽  
Vol 306 (12) ◽  
pp. G1099-G1107 ◽  
Author(s):  
Maya Muramatsu ◽  
Tohru Hira ◽  
Arimi Mitsunaga ◽  
Eri Sato ◽  
Shingo Nakajima ◽  
...  

The calcium-sensing receptor (CaSR) is expressed in various tissues, including the gastrointestinal tract. To investigate the role of gut CaSR on glycemic control, we examined whether single oral administration of CaSR agonist peptides affected the glycemic response in rats. Glucose tolerance tests were performed under oral or duodenal administration of various CaSR agonist peptides (γGlu-Cys, protamine, and poly-d-lysine hydrobromide) in conscious rats. Involvement of CaSR was determined by using a CaSR antagonist. Signaling pathways underlying CaSR agonist-modified glycemia were investigated using gut hormone receptor antagonists. The gastric emptying rate after the administration of CaSR agonist peptides was measured by the phenol red recovery method. Oral and duodenal administration of CaSR agonist peptides attenuated glycemic responses under the oral glucose tolerance test, but the administration of casein did not. The promotive effect on glucose tolerance was weakened by luminal pretreatment with a CaSR antagonist. Treatment with a 5-HT3 receptor antagonist partially diminished the glucose-lowering effect of peptides. Furthermore, the gastric emptying rate was decreased by duodenal administration of CaSR agonist peptides. These results demonstrate that activation of the gut CaSR by peptide agonists promotes glucose tolerance in conscious rats. 5-HT3 receptor and the delayed gastric emptying rate appear to be involved in the glucose-lowering effect of CaSR agonist peptides. Thus, activation of gut CaSR by dietary peptides reduces glycemic responses so that gut CaSR may be a potential target for the improvement of postprandial glycemia.


Author(s):  
Mallikarjuna Rao Talluri ◽  
Rajananda Swamy Tadi ◽  
Ganga Rao Battu ◽  
Zubair Mohammad

2020 ◽  
Author(s):  
Eva Svehlikova ◽  
Ines Mursic ◽  
Thomas Augustin ◽  
Christoph Magnes ◽  
David Gerring ◽  
...  

OBJECTIVE <p>To investigate the pharmacokinetic and pharmacodynamic properties, and safety of a novel formulation of insulin aspart (AT247) versus currently marketed insulin aspart formulations (IAsp and faster IAsp).</p> <p> </p> <p>RESEARCH DESIGN AND METHODS</p> <p>This single-center, randomized, double-blind, three-period, crossover study was conducted in 19 men with type 1 diabetes, receiving single dosing of trial products (0.3 U/kg) in a random order on three visits. Pharmacokinetics and pharmacodynamics were assessed during a euglycemic clamp lasting up to 8 hours. </p> <p> </p> <p>RESULTS</p> <p>Onset of insulin appearance was earlier for AT247 compared with IAsp (−12 minutes [95% CI −14;−8] p=0.0004) and faster IAsp (−2 minutes [−5;−2] p=0.0003). Onset of action was accelerated compared with IAsp (−23 minutes [−37;−15] p=0.0004) and faster IAsp (−9 minutes [−11;−3] p=0.0006). Within the first 60 minutes, a higher exposure was observed for AT247 compared with IAsp (AUC<sub>Asp,0-60min</sub>: treatment ratio vs IAsp 2.3 [1.9;2.9]; vs faster IAsp 1.5 [1.3;1.8]), which was underpinned by a greater early glucose-lowering effect (AUC<sub>GIR,0-60min</sub>: treatment ratio vs IAsp 2.8 [2.0;5.5]; vs faster IAsp 1.7 [1.3;2.3]). Furthermore, an earlier offset of exposure was observed for AT247 compared with IAsp (−32 minutes [−58;−15] p=0.0015) and faster IAsp (−27 minutes [−85;−15] p=0.0017), while duration of glucose-lowering effect, measured by t<sub>Late50%GIRmax</sub>, did not differ significantly.</p> <p> </p> <p>CONCLUSIONS</p> <p>AT247 exhibited an earlier insulin appearance, exposure and offset, with corresponding enhanced early glucose-lowering effect compared with IAsp and faster IAsp. It therefore represents a promising candidate in the pursuit for second generation prandial insulin analogs to improve postprandial glycemic control.</p>


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