The effect of diet composition on plasma and intestinal concentrations of immunoreactive gastric inhibitory polypeptide (GIP) and intestinal K cell density was examined in obese hyperglycaemic (ob/ob) mice. The mice were reared from 3 to 11 weeks of age on either stock diet, a high fat (HF) cafeteria diet or a high carbohydrate (HC) cafeteria diet. The HF cafeteria diet increased the concentration of GIP in plasma (75%) and in the intestine (118%) and increased the density (54%) of GIP-secreting K cells in the upper jejunum compared with the stock diet. Plasma and intestinal GIP concentrations were not significantly altered by the HC cafeteria diet, although the density of K cells in the upper jejunum was increased (45%). The extent of hyperglycaemia and hyperinsulinaemia in ob/ob mice was not significantly altered by the HF and HC cafeteria diets. The results indicate that an increased amount of dietary fat chronically stimulates the production and secretion of GIP, and enhances intestinal K cell density in ob/ob mice.Obese hyperglycaemic (ob/ob) mice exhibit a par¬ ticularly severe obesity and hyperinsulinaemia, marked hyperphagia and moderate hyperglycae¬ mia (Bray & York 1979; Bailey et al. 1982). Recent studies have identified excessive concentrations of immunoreactive gastric inhibitory polypeptide (GIP) in the small intestine and plasma of these mice (Flau et al. 1983, 1984a) associated with hyperplasia and increased hormone content of the intestinal GIP-secreting cells (Polak et al. 1975). Considerable evidence has implicated GIP as a physiological component of the enteroinsular axis (Brown 1982;Creutzfeldt et al. 1983), and hypersécrétion of GIP has been suggested as a factor contributing to the hyperinsulinaemia of ob/ob mice (Flatt et al. 1984a,b). The raised GIP concentrations of ob/ob mice render this mutant a convenient model for studies of GIP physiology. As noted in other species (Brown 1982), orally administered fat elicits a greater acute plasma GIP response than other nutrients in ob/ob mice (Flatt et al. 1984a), but the long-term effects of different dietary components on plasma and intestinal GIP remain to be established.The present study examines the chronic effects of excess fat and excess carbohydrate on the de¬ velopment of raised GIP concentrations in young ob/ob mice fed for 8 weeks on high fat and high carbohydrate cafeteria diets. Materials and Methods AnimalsObese hyperglycaemic (ob/ob) mice and lean (+/+) mice on the Aston background were housed as previ¬ ously (Flatt et al. 1984a). The origin and characteristics of these mice have been described elsewhere (Flatt & Bailey 1981;Bailey et al. 1982). DietsGroups of mice were fed either stock diet (Mouse breeding diet,

Samples of tea (Quingmao, steamed, black and Pu'er) produced in Yunnan Province, People's Republic of China, from the locally characteristic large-leaved Camellia sinensis, have been brewed and the brews analysed for their contents of flavonol glycosides, flavan-3-01s and their oxidation products. Several samples of Pu'er tea manufactured in the 192Os, 1930s and 1940s were also examined. The brews prepared from Quingmao tea and steamed green tea leaf were very similar containing primarily flavan-3-01s accompanied by flavonol glycosides, theogallin and gallic acid. The profile of flavanols was unusual, being dominated by (-)-epicatechingallate (rather than ( -)-epigallocatechingallate) and by an unusually large (+)-catechin content. The brew of the equivalent black tea retained significant amounts of residual flavanols (particularly (-)-epicatechingallate and ( +)-catechin), and contained significant amounts of thearubigins, theaflavic acids and theaflavins (including the less common analogues probably derived from the oxidation of ( + kcatechin). The brews prepared from the Pu'er teas were distinguishable from the black tea brew by the absence of theaflavins and theaflavic acids, and by much smaller residues of flavanols and flavonol glycosides. The contents of thearubigins varied considerably whereas those of gallic acid were similar.

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