title: Coffee improves insulin-stimulated Akt phosphorylation in liver and skeletal muscle in diabetic KK-A(y) mice.
abstract: Coffee has an anti-diabetic effect, specifically the amelioration of both hyperglycemia and insulin resistance, in KK-A(y) mice, a type 2 diabetes animal model. To investigate coffee's effect on insulin signaling in liver, skeletal muscle, and adipose tissue (epididymal fat), we assayed the tyrosine phosphorylation of insulin receptor (IR) and serine phosphorylation of Akt. In Expt. 1, we assayed insulin signaling under nonfasting conditions in KK-A(y) mice that ingested water or coffee for 4 wk. Coffee ingestion ameliorated the development of hyperglycemia but did not affect insulin signaling in liver or skeletal muscle under such conditions. In Expt. 2, we assayed insulin signaling under basal and insulin-stimulated conditions in KK-A(y) mice that ingested water or coffee for 3 wk. The levels of tyrosine phosphorylation of insulin receptor in response to insulin injection in insulin-sensitive tissues were not different between mice that drank water and those that drank coffee. Coffee ingestion significantly increased the insulin-induced serine phosphorylation of Akt in liver and skeletal muscle, but not in epididymal fat, of KK-A(y) mice. Our results also indicated that coffee ingestion may contribute to the improvement of insulin resistance and hyperglycemia in KK-A(y) mice via the activation of Akt in insulin signaling in liver and skeletal muscle.
authors: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Japan.
authors: Misato
authors: M
authors: Kobayashi
authors: Yuji
authors: Y
authors: Matsuda
authors: Hiroshi
authors: H
authors: Iwai
authors: Masanori
authors: M
authors: Hiramitsu
authors: Takashi
authors: T
authors: Inoue
authors: Takao
authors: T
authors: Katagiri
authors: Yoko
authors: Y
authors: Yamashita
authors: Hitoshi
authors: H
authors: Ashida
authors: Atsushi
authors: A
authors: Murai
authors: Fumihiko
authors: F
authors: Horio
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects; D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D001835:Body Weight; D003069:Coffee / Q000378:metabolism*; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy*; D006943:Hyperglycemia / Q000188:drug therapy; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000097:blood*; D007333:Insulin Resistance; D008099:Liver / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D011972:Receptor, Insulin / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D015398:Signal Transduction; D014443:Tyrosine / Q000378:metabolism
chemical_list: D001786:Blood Glucose; D003069:Coffee; D007004:Hypoglycemic Agents; D007328:Insulin; D014443:Tyrosine; D012694:Serine; D011972:Receptor, Insulin; D051057:Proto-Oncogene Proteins c-akt