1 The aim of the present study was to characterize functional responses to ropinirole, its major metabolites in man (SKF-104557 (4-[2-(propylamino)ethyl]-2-(3H) indolone), SKF-97930 (4-carboxy-2-(3H) indolone)) and other dopamine receptor agonists at human dopamine D 2(long) (hD 2 ), D 3 (hD 3 ) and D 4.4 (hD 4 ) receptors separately expressed in Chinese hamster ovary cells using microphysiometry.2 All the receptor agonists tested (ropinirole, SKF-104557, SKF-97930, bromocriptine, lisuride, pergolide, pramipexole, talipexole, dopamine) increased extracellular acidi®cation rate in Chinese hamster ovary clones expressing the human D 2 , D 3 or D 4 receptor. The pEC 50 s of ropinirole at hD 2 , hD 3 and hD 4 receptors were 7.4, 8.4 and 6.8, respectively. Ropinirole is therefore at least 10 fold selective for the human dopamine D 3 receptor over the other D 2 receptor family members. 3 At the hD 2 and hD 3 dopamine receptors all the compounds tested were full agonists as compared to quinpirole. Talipexole and the ropinirole metabolite, SKF-104557, were partial agonists at the hD 4 receptor. 4 Bromocriptine and lisuride had a slow onset of agonist action which precluded determination of EC 50 s. 5 The rank order of agonist potencies was dissimilar to the rank order of radioligand binding anities at each of the dopamine receptor subtypes. Functional selectivities of the dopamine receptor agonists, as measured in the microphysiometer, were less than radioligand binding selectivities. 6 The results show that ropinirole is a full agonist at human D 2 , D 3 and D 4 dopamine receptors. SKF-104557 the major human metabolite of ropinirole, had similar radioligand binding anities to, but lower functional potencies than, the parent compound.

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Recent studies have shown that the marked adiposity of the obese phenotype of the LA/Ntul/ /-cp rat to be associated with hyperinsulinemia, hyperamylinemia, and impaired glucose tolerance following an oral glucose challenge when compared to glycemic responses of similarly-fed lean littermates, and to be linked to a hypothalamic receptor defect for the obesity hormone, leptin. To determine the effects of an inulin fructan polymer-chromium complex (FCC) derived from dahlia root juice on glycemic responses, groups of congenic lean and obese LA/Ntul//-cp rats were administered an oral glucose tolerance (OGT) alone or in combination with measured amounts of the FCC. Glycemic responses and the glucose area under the curve (AUC) of obese rats were significantly impaired compared to similarly-fed lean littermates. Oral FCC administration resulted in a significant 50% reduction toward normal of the peak glycemic response during OGT in both lean and obese rats, a 75% reduction in the total glucose area of lean rats and a 50% reduction of the total glucose area of obese rats. The greatest segment of the reduced glucose area occurred during the post absorptive phase of the OGT response in both phenotypes. The results of this study are consistent with an acute FCC-mediated improvement in glycemic control in a congenic obese animal model of impaired glucose tolerance, and suggest that the FCC complex may be a useful nutraceutical adjunct in the dietary treatment of obesity and other glucose-intolerant states as they may occur in man and animals.Keywords: fructan, inulin, glucose tolerance, obesity, rat, chromium Journal of Nutritional Health & Food Engineering Research ArticleOpen Access Effect of a fructan-chromium complex on glycemic responses of congenic obese la/ntul//-cp rats 595Copyright: ©2016 Tulp et al. Citation:Tulp OL, Brown T. Effect of a fructan-chromium complex on glycemic responses of congenic obese la/ntul//-cp rats .