A series of very potent derivatives of the 30-amino acid peptide hormone glucagon-like peptide-1 (GLP-1) is described. The compounds were all derivatized with fatty acids in order to protract their action by facilitating binding to serum albumin. GLP-1 had a potency (EC(50)) of 55 pM for the cloned human GLP-1 receptor. Many of the compounds had similar or even higher potencies, despite quite large substituents. All compounds derivatized with fatty acids equal to or longer than 12 carbon atoms were very protracted compared to GLP-1 and thus seem suitable for once daily administration to type 2 diabetic patients. A structure-activity relationship was obtained. GLP-1 could be derivatized with linear fatty acids up to the length of 16 carbon atoms, sometimes longer, almost anywhere in the C-terminal part without considerable loss of potency. Derivatization with two fatty acid substituents led to a considerable loss of potency. A structure-activity relationship on derivatization of specific amino acids generally was obtained. It was found that the longer the fatty acid, the more potency was lost. Simultaneous modification of the N-terminus (in order to obtain better metabolic stability) interfered with fatty acid derivatization and led to loss of potency.

The long-acting GLP-1 derivative NN2211 ameliorates glycemia and increases ␤-cell mass in diabetic mice.

We here report a series of derivatives describing the structure-activity relationship around liraglutide, a once-daily human glucagon-like peptide-1 fatty acid derivative, with respect to potency as well as protraction in vivo. The spacer region between the fatty acid and the peptide is mostly important for potency, whereas the fatty acid or fatty acid mimetic is important for both potency and protraction. The length of the fatty acid is the most important parameter for protraction.

1 Liraglutide is a long-acting GLP-1 derivative, designed for once daily administration in type II diabetic patients. To investigate the effects of liraglutide on glycemic control and b-cell mass in rat models of b-cell deficiencies, studies were performed in male Zucker diabetic fatty (ZDF) rats and in 60% pancreatectomized rats. 2 When liraglutide was dosed s.c. at 150 mg kg À1 b.i.d. for 6 weeks in ZDF rats 6 -8 weeks of age at study start, diabetes development was markedly attenuated. Blood glucose was approximately 12 mm lower compared to vehicle (Po0.0002), and plasma insulin was 2 -3-fold higher during a normal 24-h feeding period (Po0.001). Judged by pair feeding, approximately 53% of the antihyperglycemic effect observed on 24-h glucose profiles was mediated by a reduction in food intake, which persisted throughout the study and averaged 16% (Po0.02). 3 Histological analyses revealed that b-cell mass and proliferation were significantly lower in prediabetic animals still normoglycemic after 2 weeks treatment compared to vehicle-treated animals that had begun to develop diabetes. When the treatment period was 6 weeks, the liraglutide-treated animals were no longer completely normoglycemic and the b-cell mass was significantly increased compared to overtly diabetic vehicle-treated animals, while b-cell proliferation was unaffected. 4 In the experiments with 60% pancreatectomized rats, 8 days treatment with liraglutide resulted in a significantly lower glucose excursion in response to oral glucose compared to vehicle treatment. Again, part of the antihyperglycemic effect was due to reduced food intake. No effect of liraglutide on b-cell mass was observed in these virtually normoglycemic animals. 5 In conclusion, treatment with liraglutide has marked antihyperglycemic effects in rodent models of b-cell deficiencies, and the in vivo effect of liraglutide on b-cell mass may in part depend on the metabolic state of the animals.

No abstract

Intermediate NIA doses induced moderate changes of glucose tolerance [glucose area under the curve increased from 940 Ϯ 175 to 1,598 Ϯ 462 mM ⅐ min, P Ͻ 0.001 (100 mg/kg) and from 890 Ϯ 109 to 1,669 Ϯ 691 mM ⅐ min, P ϭ 0.003 (67 mg/kg)] with reduced insulin secretion [1,248 Ϯ 602 pM ⅐ min after 16 days and 1,566 Ϯ 190 pM ⅐ min after 60 days vs. 3,251 Ϯ 804 pM ⅐ min in normal animals (P Ͻ 0.001)] and ␤-cell mass [5.5 Ϯ 1.4 mg/kg after 27 days and 7.9 Ϯ 4.1 mg/kg after 60 days vs. 17.7 Ϯ 4.7 mg/kg in normal animals (P ϭ 0.009)]. The combination of NIA and STZ provided a model characterized by fasting and especially postprandial hyperglycemia and reduced, but maintained, insulin secretion and ␤-cell mass. This model holds promise as an important tool for studying the pathophysiology of diabetes and development of new pharmacological agents for treatment of the disease.in vivo pharmacology; large-animal model; glucose tolerance; ␤-cell reduction; glucose-stimulated insulin secretion.THE STUDY OF THE PATHOPHYSIOLOGY and treatment of diabetes requires well characterized animal models that resemble aspects of the disease in humans. Various forms of diabetes occur spontaneously or can be induced in several species of animals. Most of the available models are based on rodents; however, nonrodent models of diabetes are urgently needed as a valuable supplement to rodents for both practical and physiological reasons.The pig is useful as a model for human physiology and pathophysiology, because many organ systems resemble those of the human. Of special interest for the study of diabetes is the similarities to humans found in the clinical chemistry (7,10,12,14,24,26,55), nutrition and gastrointestinal tract (4,8,11,20,35,40,51), pancreas development and morphology (21,36,37,44,49,54), and metabolism (3, 35). These characteristics make swine an interesting species for studies of metabolic abnormalities in diabetes. The Göttingen minipig is especially suitable for long-term studies because of its small size and ease of handling, even at full maturity (6).Pancreatectomy has been investigated as a method of inducing diabetes in pigs (33,34,50,55). However, high rates of mortality have been observed postoperatively (50, 55), meaning that this technique should be used with great caution, and alternatives should be considered because of welfare considerations. Chemical induction of diabetes offers the advantage of preservation of both exocrine and endocrine cell populations other than ␤-cells, thus resembling the situation in human diabetes (55). Several stable models have been established for overt type 1 diabetes in the pig by the use of pharmacological induction of ␤-cell damage with streptozotocin (STZ), either as single or repeated injections (2, 15, 16, 27-29, 46, 55). Substantially increased fasting plasma glucose (FPG) levels and decreased insulin secretion in response to glucose stimuli have been obtained as well as increases in plasma triglycerides and total cholesterol (27,29). Late complications typical of diabetes, such...

Objective: It has earlier been demonstrated that capsaicin-induced desensitization improves insulin sensitivity in normal rats. However, whether increased capsaicin-sensitive nerve activity precedes the onset of insulin resistance in diet-induced obesity -and therefore might be involved in the pathophysiology -is not known. Further, it is of relevance to investigate whether capsaicin desensitization improves glycaemic control even in obese individuals and we therefore chose the obese Zucker rats to test this. Design and methods: Plasma levels of calcitonin gene-related peptide (CGRP; a marker of sensory nerve activity) was assessed in 8-week-old Zucker rats. To investigate whether capsaicin desensitization (100 mg/kg at 9 weeks of age) would also ameliorate glycaemia in this non-diabetic model, we assessed oral glucose tolerance at 7 weeks after capsaicin. Results: It was found that plasma CGRP levels were elevated in obese Zucker rats prior to the onset of obesity (16.1^3.4 pmol/l in pre-obese Zucker rats vs 6.9^1.1 pmol/l in lean littermates; P ¼ 0.015) despite similar body weights. Furthermore, capsaicin desensitization reduced both fasting blood glucose (4.3^0.2 mmol/l vs 5.1^0.2 mmol/l in controls; P ¼ 0.050) as well as the mean blood glucose level during an oral glucose tolerance test (OGTT) (6.8^0.3 mmol/l vs 8.6^0.5 mmol/l in control obese rats; P ¼ 0.024) whereas the plasma insulin levels during the OGTT were unchanged. However this did not lead to an improvement in insulin resistance or to a reduction of tissue triglyceride accumulation in muscle or liver. Conclusion: We concluded that capsaicin-induced sensory nerve desensitization improves glucose tolerance in Zucker rats. Since, in this study, plasma CGRP levels, a marker of sensory nerve activity, were increased in the pre-obese rats, our data support the hypothesis that increased activity of sensory nerves precedes the development of obesity and insulin resistance in Zucker rats. European Journal of Endocrinology 153 963-969

Five activated carbons (ACs) and two biochars were tested as amendments to reduce the availability of aged polychlorinated dibenzo-p-dioxin/dibenzofurans (PCDD/Fs) in two soils. All sorbents (ACs and biochars) tested substantially reduced the availability of PCDD/Fs measured by polyoxymethylene (POM) passive uptake and earthworm (E. fetida) biouptake. Seven sorbents amended at a level of 0.2 × soil total organic carbon (0.2X) reduced the passive uptake (physicochemical availability) of total PCDD/Fs in POM by 40% to 92% (or toxic equivalent by 48% to 99%). Sorbents with finer particle sizes or more macropores showed higher reduction efficiencies. The powdered regenerated AC and powdered coconut AC demonstrated to be the most effective and the two biochars also performed reasonably well especially in the powdered form. The passive uptake of PCDD/F in POM increased approximately 4 to 5 fold as the contact time between POM and soil slurry increased from 24 to 120 d while the efficacy of ACs in reducing the physicochemical availability remained unchanged. The reduction efficiencies measured by POM passive uptake for the regenerated AC were comparable to those measured by earthworm biouptake (bioavailability) at both dose levels of 0.2X and 0.5X. The biota-soil accumulation factor (BSAF) values for unamended soil ranged from 0.1 for tetra-CDD/F to 0.02 for octa-CDD/F. At both dose levels, the regenerated AC reduced the BSAFs to below 0.03 with the exception of two hexa-CDD/Fs. The reduction efficiencies measured by earthworm for coconut AC and corn stover biochar were generally less than those measured by POM probably due to larger particle sizes of these sorbents that could not be ingested by the worms.