Yellow KK Mice Research Articles

Age dependence of glucose tolerance in adult KK-Ay mice, a model of non–insulin dependent diabetes mellitus

Yellow KK mice carrying the 'yellow obese' gene Ay are a well established polygenic model for human non-insulin dependent diabetes mellitus. These animals develop marked adiposity and decreased glucose tolerance relative to their control littermates, KK mice. The authors monitored glucose tolerance in KK-Ay mice over time and observed a significant (P<or=0.05) age-dependent improvement (13.3% by 175 d of age and 36.4% by 212 d of age, relative to 85 d of age). During the same time period, body weight and food and water consumption were relatively constant. The authors also measured plasma levels of endocrine hormones that are important in diabetes. Levels of insulin were approximately 8 times higher and levels of amylin 3 times higher in 220-d-old KK-Ay mice than in 180-d-old mice, whereas levels of glucagon-like peptide 1, glucagon and leptin remained relatively constant. These findings suggest that KK-Ay mice undergo an age-dependent improvement of glucose tolerance when maintained on a normal diet for 25 weeks or longer, due in part to increases in plasma levels of insulin and amylin.

Effects of caffeine on the uncoupling protein family in obese yellow KK mice.

1. The hypothesis that caffeine upregulates uncoupling protein (UCP)-1, UCP-2 and UCP-3 expression, which contribute to thermogenesis, was investigated in obese mice. 2. The mRNA levels of UCP-1, -2 and -3 in brown adipose tissue (BAT), UCP-2 in white adipose tissue (WAT), and UCP-2 and -3 in skeletal muscle were measured using real-time quantitative reverse transcription-polymerase chain reaction analysis in obese yellow KK mice 4 h after the subcutaneous administration of either 60 mg/kg caffeine or physiological saline. Plasma free fatty acids, adrenaline, noradrenaline and dopamine levels were also measured. 3. In caffeine-injected obese mice, UCP-1 mRNA levels were significantly increased by 1.5-fold in BAT, UCP-2 mRNA levels were increased by 1.8- and 2.5-fold in BAT and skeletal muscles, respectively, and UCP-3 mRNA levels were increased 1.7- and 3.4-fold in BAT and skeletal muscles, respectively, compared with control mice injected with physiological saline. There was no difference in UCP-2 mRNA levels in WAT between the two groups. 4. Plasma free fatty acids and adrenaline levels were significantly elevated in mice treated with caffeine compared with those injected with physiological saline. 5. It was concluded that caffeine upregulates the expression of UCP-1, UCP-2 and UCP-3 in BAT and UCP-2 and UCP-3 in skeletal muscles, which may contribute to thermogenesis in obese mice.

Up-Regulation of the Uncoupling Protein Family by Chronic Treatment with a .BETA.3-Adrenergic Receptor Agonist in Obese Yellow KK Mice

Chronic stimulation of the β3-adrenergic receptor in obese mice resulted in a reduced adiposity associated with the promotion of lipolysis and the increase of non-shivering thermogenesis. It is known that the mitochondrial uncoupling protein 1 (UCP 1) in brown adipose tissue (BAT) is an important key molecule for non-shivering thermogenesis. UCP2 and UCP3 were recently cloned, but the effect on the UCP family (UCP1, UCP2, and UCP3) of a β3-adrenergic receptor agonist is unclear. Therefore, in this study, the effect of a β3-adrenergic receptor agonist on UCP1, UCP2, and UCP3 was investigated in BAT, white adipose tissue (WAT) and the gastrocnemius muscle of C57BL control and obese yellow KK mice administered with a β3-adrenergic receptor agonist, CL316, 243 for two weeks subcutaneously. UCP1 mRNA was found abundantly in BAT, but detected only slightly in subcutaneous and perimetric WAT and gastrocnemius muscle in both C57BL and yellow KK mice. UCP2 mRNA and UCP3 mRNA were also found in all of tissues examined in both mice. Daily injections of CL316, 243 resulted in a reduction of body weight and white pad weight, and in increases in the mRNA levels of UCP1 in BAT, WAT, and gastrocnemius muscle, UCP2 in BAT and WAT, UCP3 in BAT and perimetric WAT in both groups. These results suggest that a β3-adrenergic receptor agonist up-regulates not only UCP1 mRNA in BAT, WAT, and gastrocnemius muscle, but also UCP2 and UCP3 mRNA in BAT and WAT, and the whole UCP family may contribute to increased thermogenesis and anti-obesity action following the administration of a β3-adrenergic receptor agonist.

Beta 3-adrenergic agonist up-regulates uncoupling proteins 2 and 3 in skeletal muscle of the mouse.

Chronic stimulation of the beta3-adrenergic receptor (AR) in obese animals resulted in a reduced adiposity associated with an increased expression of thermogenic uncoupling protein (UCP)1 in adipose tissues. In this study, the mRNA expression of newly cloned UCP isoforms (UCP2 and UCP3) were examined in obese yellow KK and C57BL control mice. UCP2 mRNA was found in all tissues examined, with higher levels in adipose tissues and skeletal muscle of the obese mice. UCP3 mRNA was expressed in skeletal muscle, heart and brown adipose tissue similarly in the two mouse strains. Daily injection of a selective beta3-adrenergic agonist, CL316,243 (0.1 mg/kg), for 10 days resulted in a marked reduction of white fat pad weight and 1.8-4.8-fold increase in the mRNA levels of UCP2 and UCP3 in skeletal muscle of obese mice. No noticeable change in the UCP2 and 3 mRNA levels was found in brown and white adipose tissues. It was also found that CL316,243 injection produced a marked and sustained elevation of the plasma free fatty acid level. These results, together with our previous findings of the fatty acid-induced UCP expression in a myocyte cell line in vitro, suggest that the beta3-AR agonist-induced UCP expression in skeletal muscle may be mediated through the elevated plasma free fatty acids. It was also suggested that anti-obesity effect of beta3-AR agonists is attributable to increased thermogenesis not only by UCP1 but also by UCP2 and UCP3.

Soy protein isolate and its hydrolysate reduce body fat of dietary obese rats and genetically obese mice (yellow KK)

This study examined in dietary obese and genetically obese rodents the effects of soy protein isolate (SPI) and its hydrolysate (SPI-H) on the rate of body-fat disappearance. Male Sprague-Dawley rats (4–16 wk old) and yellow KK mice (6–10 wk old) were made obese by feeding high-fat diets containing 30% fat. They were then fed energy-restricted, low-fat (5.0%), and high-protein (35% casein, SPI, or SPI-H) diets for 4 wk at 60% of the level of the energy intake of rodents on laboratory chow. The body-fat contents of rats and mice fed a high-fat diet were 27.3 and 33.6 g/100 g body weight, respectively, at the end of the obese period. For rats, the apparent absorbability of dietary energy and fat was significantly lower in the SPI and SPI-H groups than in the casein group, but vice-versa for nitrogen balance. Body-fat content in mice fed SPI and SPI-H diets was significantly lower than in those fed the casein diet. In rats, plasma total cholesterol level was lower with the SPI-H diet, and plasma glucose level was lower with the SPI and SPI-H diets than with the casein diet. These results indicate that SPI and SPI-H are suitable protein sources in energy-restricted diets for the treatment of obesity.

T-1095, an inhibitor of renal Na+-glucose cotransporters, may provide a novel approach to treating diabetes.

T-1095A and T-1095 are synthetic agents derived from phlorizin, a specific inhibitor of Na+-glucose cotransporters (SGLTs). Unlike phlorizin, T-1095 is absorbed into the circulation via oral administration, is metabolized to the active form, T-1095A, and suppresses the activity of SGLTs in the kidney. Orally administered T-1095 increases urinary glucose excretion in diabetic animals, thereby decreasing blood glucose levels. Indeed, the postprandial hyperglycemia after a meal load was shown to be suppressed by this compound in streptozotocin (STZ)-induced diabetic rats. With long-term T-1095 treatment, both blood glucose and HbA1c levels were reduced in STZ-induced diabetic rats and yellow KK mice. In addition, there was amelioration of abnormal carbohydrate metabolism, i.e., hyperinsulinemia and hypertriglyceridemia, and of the development of microalbuminuria, in yellow KK mice. Thus, T-1095 may be a useful antidiabetic drug, providing a novel therapeutic approach for diabetes.

Nicotine induces uncoupling protein 1 in white adipose tissue of obese mice.

To test the hypothesis that nicotine not only activates uncoupling protein1 (UCP1) in brown adipose tissue (BAT), but also induces UCP1 in white adipose tissue (WAT), which contributes to the mitigation of obesity in obese mice. Weights of the whole body, the gastrocnemius muscle, interscapular BAT and subcutaneous and retroperitoneal WAT, food intake and the mRNA and protein of UCP1 in these tissues were measured and immunohistochemistry using antiserum against UCP1 was also performed in obese yellow KK mice treated with nicotine for 6 months and control mice treated with physiological saline. Obese mice treated with nicotine for 6 months, compared with those injected with saline, weighed significantly less (P < 0.01) and had smaller subcutaneous and retroperitoneal WAT pads (P < 0.01), while obese mice that received nicotine ate less (P < 0.05) than those injected with saline. In mice treated with nicotine, the mRNA and protein of UCP1 was detected not only in BAT, but also in subcutaneous and retroperitoneal WATs. Immunohistochemically, the BAT of obese mice contained large lipid droplets and appeared rather WAT-like, but changed to typical brown adipocytes after nicotine treatment. The fat pads of nicotine-treated mice contained many multilocular cells that were positive for UCP1. Nicotine not only activates UCP1 in BAT, but also induces UCP1 in WAT and decreases food intake, which contributes to the mitigation of obesity.

BM 17.0744: A structurally new antidiabetic compound with insulin-sensitizing and lipid-lowering activity

BM 17.0744 (2,2-dichloro-12-( p-chlorophenyl)-dodecanoic acid) is a substance from a group of ω-substituted alkyl carboxylic acids with the general formula, ring-spacer-carboxylic acid. With BM 17.0744—a compound structurally unrelated to thiazolidinediones—antihyperglycemic and antihyperinsulinemic potency has been demonstrated in various animal models of type II diabetes. The antidiabetic effect is independent of the genetic background of the disease, gender, and animal species. The 24-hour blood glucose profile was dose- and time-dependently improved in ob ob mice after a single and fourth oral administration of 0.3, 1, and 3 mg/kg/d. A dose-dependent reduction of hyperglycemia (10%, 15%, 28%, and 66%) was found in rmdb db mice after the fifth oral administration of 3, 10, 30, and 100 mg/kg/d. Hyperinsulinemia was reduced dose-dependently in yellow KK mice by 1%, 24%, 34%, and 66% after the fifth oral administration of 0.3, 1, 3, and 10 mg/kg/d. Overall glucose metabolism was predominantly higher in euglycemic-hyperinsulinemic clamp studies in obese rmfa fa rats pretreated for 14 days with 10 mg/kg/d BM 17.0744. The data in diabetic and insulin-resistant animals suggest an improvement of insulin action that is supported by enhancement of insulin effects in vitro. There is no evidence of a risk for hypoglycemia in diabetic and metabolically healthy animals. Triglyceride (TG) and cholesterol were reduced in the serum of metabolically healthy rats, as well as serum lipids in db db mice, which suggests this effect is independent of amelioration of the diabetic status. Lipid-lowering effects in diabetic and healthy animals show an additional property of BM 17.0744. Because of its antidiabetic and lipid-lowering potency, the substance is of great interest in treating the metabolic syndrome. Lipid decreases in rats are associated with a dose-dependent increase in carnitine acetyltransferase activity in the liver to about 100-fold (12.5 mg/kg/dl). This together with hepatomegaly in small rodents may indicate peroxisomal proliferation, a phenomenon considered species-specific. Its relevance for humans is well documented for other classes of compounds including fibrates. Specific side effects of insulin sensitizers of the thiazolidinedione type, such as an increase in body weight and heart weight, could not be observed after 4-week oral application of BM 17.0744 in rats. In general, BM 17.0744 was well tolerated in the pharmacological dose range in all species tested.

Beta 3-Adrenergic agonist induces a functionally active uncoupling protein in fat and slow-twitch muscle fibers.

The mitochondrial uncoupling protein (UCP) has usually been found only in brown adipose tissue. We recently observed that a chronic administration of the beta 3-adrenergic agonist CL-316,243 (CL) induced the ectopic expression of UCP in white fat and skeletal muscle in genetic obese yellow KK mice. The aim of the present study was to examine whether UCP could be induced in nongenetic obese animals produced by neonatal injections of monosodium L-glutamate (MSG). The daily subcutaneous injection of CL (0.1 mg/kg) to MSG-induced obese mice for 2 wk caused significant reductions of body weight (15%) and white fat pad weight (58%). Northern and Western blot analyses showed that CL induced significant expressions of UCP in the white fat and muscle, as well as in brown fat. Immunohistochemical observations revealed that the UCP stains in white fat were localized on multilocular cells and that those in muscle were localized on slow-twitch fibers rich in mitochondria. Immunoelectron microscopy confirmed the mitochondrial localization of UCP in the myocytes. The guanosine 5'-diphosphate (GDP) binding to mitochondria in brown fat doubled after the CL treatment. Moreover, significant GDP binding was detected in the white fat and muscle of the CL-treated mice, at about one-fourth and one-thirteenth the activity of brown fat, respectively, suggesting that ectopically expressed UCP is functionally active. We concluded that the beta 3-adrenergic agonist CL can induce functionally active UCP in white fat and slow-twitch muscle fibers of obese mice.

Acute and chronic regulation of ob mRNA levels by beta3-adrenoceptor agonists in obese Yellow KK mice.

The inhibitory effect of beta3-adrenoceptor agonists on the ob gene in brown adipose tissue (BAT) and white adipose tissue (WAT) is now well documented both in vivo in lean animals and in vitro, but the reported effects of beta3-adrenoceptor agonists on ob gene expression in obese animals remain controversial. We investigated whether ob gene expression in BAT and WAT is reduced by acute and chronic administrations of a beta3-adrenoceptor agonist, CL316,243 (CL). The ob gene mRNA levels in BAT, perimetric and inguinal WAT of obese Yellow KK mice were about 4-fold higher than those of lean controls. Acute exposure (6 h) to CL decreased ob gene mRNA levels in three fat depots in both animals. Chronic exposure (10 days) to CL also decreased ob gene mRNA levels in BAT, perimetric, and inguinal WAT in both animals. We concluded that acute and chronic regulation by a beta3-adrenoceptor agonist suppressed ob gene expression in obese Yellow KK mice and lean controls.

Anti-obesity and anti-diabetic effects of mazindol in yellow KK mice: its activating effect on brown adipose tissue thermogenesis.

1. The anti-obesity and anti-diabetic effects of mazindol were evaluated in obese diabetic yellow KK mice and C57Bl control mice. 2. The study compound was fed through a gastric tube at a rate of 1 or 2 mg/kg per day (0.01 mol/L HCl as control) for 2 weeks. The following parameters were compared in treated and control animals: bodyweight, food intake, white adipose tissue (WAT) weight, brown adipose tissue (BAT) weight and its thermogenesis, noradrenaline (NA) turnover, blood glucose and serum insulin levels and glucose transporter 4 (GLUT4). 3. Furthermore, bodyweight loss of mice pair-fed the same amount of food as the mazindol-treated mice for 2 weeks was measured. 4. Mazindol significantly decreased food intake and significantly increased guanosine-5'-diphosphate-binding in BAT mitochondria and NA turnover in BAT in both yellow KK and C57Bl groups. The amounts of WAT in subcutaneous, mesenteric and retroperitoneal regions and bodyweights were significantly decreased in both groups. Bodyweight loss in mice pair fed with the mazindol-treated groups was approximately 70% compared with that in the mazindol-treated groups. Furthermore, mazindol decreased the levels of blood glucose and serum insulin during the glucose overloading test in yellow KK mice, but it did not influence the GLUT4 protein concentration in WAT and muscle. 5. These observations suggest that mazindol possesses both an anti-obesity action, due to the inhibition of appetite as well as the activation of BAT thermogenesis via increased NA turnover in BAT, and an anti-diabetic action. Consequently, mazindol may be useful for the treatment of obesity as well as non-insulin-dependent diabetes mellitus in obese persons.

Expression of uncoupling protein in skeletal muscle and white fat of obese mice treated with thermogenic beta 3-adrenergic agonist.

The mitochondrial uncoupling protein (UCP) is usually expressed only in brown adipose tissue (BAT) and a key molecule for metabolic thermogenesis. The effects of a highly selective beta 3-adrenergic agonist, CL316,243 (CL), on UCP expression in skeletal muscle and adipose tissues were examined in mice. Daily injection of CL (0.1 mg/kg, sc) to obese yellow KK mice for two weeks caused a significant reduction of body weight, associated with a marked decrease of white fat pad weight and hypertrophy of the interscapular BAT with a sixfold increase in UCP content. Clear signals of UCP protein and mRNA were detected by Western and Northern blot analyses in inguinal, mesenteric and retroperitoneal white fat pads, and also in gastrocnemius and quadriceps muscles, whereas no signal in saline-treated mice. The presence of UCP mRNA in muscle tissues was also confirmed by reverse transcription-PCR analysis. Weaker UCP signals were also detected in control C57BL mice treated with CL, but only in inguinal and retroperitoneal fat pads. Immunohistochemical examinations revealed that UCP stains in the white fat pads were localized on multilocular cells quite similar to typical brown adipocyte, and those in the muscle tissues on myocytes. The mitochondrial localization of UCP in myocytes was confirmed by immunoelectron microscopy. In addition to UCP protein, UCP mRNA was also detected in myocytes by in situ hybridization analysis. Thus, chronic stimulation of the beta 3-adrenergic receptor induces ectopic expression of UCP in adipose tissues conventionally considered as white fat and even in skeletal muscle, which probably contributes to the potent anti-obesity effect of the beta 3-adrenergic agonist.

(−)-BM 13.0913: A new oral antidiabetic agent that improves insulin sensitivity in animal models of type II (non—insulin-dependent) diabetes mellitus

Insulin resistance is one of the key features of non—insulin-dependent diabetes mellitus (NIDDM). Therefore, a drug that causes an improvement in insulin sensitivity would be of great interest for the treatment of NIDDM. In addition to the insulin-sensitizing thiazolidinediones, we have found another class of insulin-sensitizing agents: the α-activated carbonic acids. (−)-BM 13.0913, a member of this class, was effective in improving insulin resistance in hyperinsulinemic and hypoinsulinemic insulin-resistant animal models of NIDDM. The 50% effective dose (ED 50) for the glucose-lowering action was 4, 2.4, and 8 mg/ kg in ob ob , yellow KK, and db db mice, respectively. The ED 50 for the insulin-lowering action was 14.5, 5, and 26 mg/ kg. This rightward shift of the dose-response curve for insulin indicates that improving glucose homeostasis is the primary effect of the drug, followed by an insulin-decreasing action. This effect on glucose homeostasis may be brought about by sensitizing peripheral target tissues to the effects of insulin. An increase in deoxyglucose uptake and glucose oxidation measured in adipocytes from rats that had been treated for 14 days with (−)-BM 13.0913 supports this conclusion. Glucose uptake and oxidation was increased at all insulin concentrations tested, suggesting an improved responsiveness. Insulin sensitivity in adipocytes was not influenced by the drug. Studies in the moderately hypoinsulinemic, low-dose streptozotocin (STZ) diabetic rat with a residual insulin concentration showed a decrease in blood glucose concentrations, as well as a decrease in urinary glucose. Data obtained with STZ-diabetic rats with no residual insulin concentration and (−)-BM 13.0913 showed no effect on blood and urinary glucose, further supporting the insulin-sensitizing action of the drug. Additionally, no clinical signs of hypoglycemia were detected in any of the animal models tested. Furthermore, a decrease in serum nonesterified fatty acids (NEFA) and triglycerides was seen with an ED 50 of 6 mg/kg. The (+)-enantiomer of BM 13.0913 showed no effect on glucose and insulin concentrations in any of the mice models tested. An enantioselective action was thus demonstrated. From these results, it is concluded that the (−)-enantiomer of BM 13.0913 may prove to bean active drug in treating insulin resistance as seen in NIDDM.

A Novel Adrenaline Derivative, AZ002, and Its Hypoglycemic Action in Yellow KK Mice

AZ002 (L-threo-(3,4-dihydroxy phenyl)-N-methyl serine methyl ester) is a newly synthesized adrenaline derivative. AZ002 caused relaxation of rat jejunum (β3-receptors) (ED50=18 μM), but did not affect the atrial rate (β1) or tracheal relaxation (β2) at a concentration of 0.3 mM. The pA2 values for propranolol in inhibiting the isoproterenol- and AZ002-stimulated relaxation of rat jejunum were 6.27 and 6.33, respectively. Thus, AZ002 is a selective agonist for β3-adrenoceptor. AZ002 stimulated lipolysis (ED50= 10 μM) and glucose uptake (ED50=1 μM) in rat adipocytes. In both cases, stimulation was antagonized by high concentrations of the β-adrenoceptor antagonist propranolol, but not by the α-adrenoceptor antagonist phentolamine. The effect of AZ002 on glucose uptake was synergistic with that of insulin. AZ002 was also assessed in vivo by using genetically obese mice (KK/Ay strain) with hyperglycemia. Administration of AZ002 in the diet for a week decreased blood glucose and non-esterified fatty acids.

Anti obserity and anti diabetic effects of Cl 316,243, highly specific β3 − adrenoceptor agonist, in MSG-induced obese mice and yellow KK mice

Anti obserity and anti diabetic effects of Cl 316,243, highly specific β3 − adrenoceptor agonist, in MSG-induced obese mice and yellow KK mice

Anti-obesity and anti-diabetic effects of CL 316, 243, a highly specific β 3-adrenoceptor agonist, in yellow KK mice

The anti-obesity and anti-diabetic effects of CL 316, 243, a highly 3pecific β 3-adrenoceptor agonist ( β 1: β 2: β 3 = 0:1:100,000), were evaluated in obese diabetic yellow KK mice and C57Bl control mice. The study compound was fed through a gastric tube at a rate of 0.1 mg/kg/ day for 2 weeks. The following parameters were compared in the treated and control animals given distilled water : brown adipose tissue thermogenesis, resting metabolic rate, insulin receptors in adipocytes, and blood glucose and serum insulin levels during a glucose overloading test. CL 316, 243 significantly increased brown adipose tissue thermogenesis and resting metabolic rate in both yellow KK mice and C57B1 controls. Theamount of white adipose tissue decrease, although food intake was not affected. The effects contributed to the mitigation of obesity in yellow KK mice. CL 316, 243 also increase the concentration of insulin receptors and decreased the levels of serum insulin and blood glucose during the glucose overloading test in yellow KK mice. These observations suggest that CL 316, 243 possesses anti-obesity and anti-diabetic effects and consequently may be useful for treating obesity as well as non-insulin-dependent diabetes mellitus in obese persons, without causing excessive side effects.

Delayed Maturation of Fetal Lung in Yellow KK Mice

Yellow KK mice have the Ay allele and spontaneously develop non-insulin dependent diabetes mellitus (NIDDM). In the present study, female yellow KK mice were mated at 7 or 13 weeks of age (the average blood glucose levels were ca. 260 and 500 mg/dl, respectively), and their fetuses were examined on days 18 or 19 of gestation. The fetuses from 13-wk-old dams were smaller than those from 7-wk-old dams. The average lung weight on day 19 of gestation was slightly greater in the fetuses from 13-wk-old dams than in those from 7-wk-old dams (23.3 vs 21.2 mg). Histologically, alveolar spaces were smaller and alveolar walls were thicker in the fetuses from 13-wk-old dams than in those from 7-wk-old dams. Morphometric analysis revealed that the percentage area of the fetal lung occupied by alveolar spaces was significantly smaller in the former fetuses than in the latter. Day-15 fetal lungs of KK mice, which do not have the Ay allele, were cultured in hyperglycemic media (glucose levels: 400 and 700 mg/dl) for 48 hr. The development of alveoli was inhibited in hyperglycemic media as compared to the development of the lungs grown in the control medium. The inhibitory effect was dependent on the glucose concentration in the media. Thus, it seems that maternal hyperglycemia itself is a major cause of the delayed maturation of the fetal lung in NIDDM mice.

Anti-Obesity and Anti-Diabetic Actions of a .BETA.3-Adrenoceptor Agonist, BRL 26830A, in Yellow KK Mice.

The anti-obesity and anti-diabetic actions of BRL 26830A, beta 3-adrenoceptor agonist, (2 mg/kg administered intramuscularly daily for 2 weeks) were evaluated in obese diabetic Yellow KK mice and C57B1 control mice. The following parameters were compared in the treated vs. control animals: brown adipose tissue (BAT) thermogenesis, resting metabolic rate (RMR), insulin receptors in adipocytes, and blood glucose and serum insulin levels during a glucose overloading test. BRL 26830A significantly increased BAT thermogenesis and RMR but it decreased the amount of white adipose tissue without affecting food intake. Those actions contributed to the mitigation of obesity in Yellow KK mice. BRL 26830A also increased the concentration of insulin receptors and decreased the levels of serum insulin and blood glucose during the glucose overloading test in Yellow KK mice. In the glucose overloading test performed one hour after BRL 26830A injection, insulin secretion was significantly increased and the blood glucose level was markedly decreased in both groups. These observations suggest that BRL 26830A possesses anti-obesity and anti-diabetic actions and consequently may be useful for treating obesity as well as non-insulin-dependent diabetes mellitus with obesity.

Studies on Antidiabetic Agents. X. Synthesis and Biological Activities of Pioglitazone and Related Compounds.

Various analogues of a new antidiabetic agent, pioglitazone (AD-4833, U-72107), were synthesized in order to study in more detail the structure-activity relationships of this class of drug. 5-(4-Pyridylalkylthiobenzyl)-2,4-thiazolidinediones (I), thia-analogues of pioglitazone, were prepared via Meerwein arylation of the alkylthioanilines (IV). 5-(4-Pyridylalkoxybenzylidene)-2,4-thiazolidinediones (IIa) and related heterocyclic analogues (IIb) were synthesized by Knoevenagel condensation of the aldehydes (VIII) with the corresponding azolidinones. Compounds I and II were evaluated for hypoglycemic and hypolipidemic activity in genetically obese and diabetic yellow KK (KKAy) mice. Several 5-[4-[2-(2-pyridyl)ethoxy]-benzylidene]-2,4- thiazolidinediones (IIa) were equipotent to pioglitazone. However, the thia-analogues (I) and the benzylideneheterocycles (IIb) had decreased activity. Catalytic hydrogenation of the 5-benzylidene analogue (14) was found to be a convenient new synthetic method for pioglitazone. The configuration of 14 is also discussed.

Embryopathy in Genetically Diabetic Mice, Yellow KK, and Its Prevention by Maternal Therapy

Abstract Embryopathy in yellow KK mice with non‐insulin dependent diabetes mellitus was examined among the conceptuses of females mated at 7, 11, and 13 weeks of age.The numbers of corpora lutea and implants were comparable in all maternal age groups. Early embryonic deaths were frequently observed in all maternal age groups (37.7 46.4%), but no significant difference was found among the groups. The incidence of late embryonic deaths was significantly higher in 11‐ and 13‐wk‐old dams (25.6% and 28.8%) than in 7‐wk‐old dams (14.4%). Moreover, in 13‐wk‐old dams, but not in 7‐wk‐old dams, a positive correlation existed between maternal plasma glucose levels on day 18 of pregnancy and late embryonic deaths. Fetuses from 13‐wk‐old dams weighed less than those from 7‐wk‐old dams (0.73 g vs 0.86 g).Yellow KK mice mated at 13 weeks of age were treated with an oral‐hypoglycemic agent, 5‐[4‐(l‐methylcyclohexylmethoxy)benzyl] thiazolidine‐2,4‐dione (ciglitazone), as an 0.1% dietary admixture. Plasma glucose on day 18 of pregnancy was lower in all treated groups (159‐170 mg/dl) than in the untreated control (345 mg/dl). A significant decrease of late embryonic deaths (12.7‐15.6%) and a slight increase of fetal weights (0.79‐0.81 g) were noted when compared with the untreated controls (36.8% and 0.74 g).