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We investigated the glucose transporter mRNAs expressed in FRTL5, a rat thyroid cell line, and their regulation by TSH by means of the polymerase chain reaction. FRTL5 cells as well as rat thyroid tissue expressed three types of glucose transporter mRNAs: GLUT1 or erythrocyte/HepG2/brain isoform, GLUT2 or pancreatic beta-cell/liver isoform, and GLUT4 or muscle/fat isoform. GLUT1 mRNA predominated, GLUT4 mRNA was minor, and GLUT2 mRNA expression was faint. Incubation of FRTL5 cells with TSH induced a time- and concentration-dependent increase in GLUT1 mRNA levels, while GLUT4 mRNA levels were decreased. The response of GLUT1 mRNA to TSH was evident at 3 h, and the maximal response was achieved at 12 h. TSH at a dose of 1 mU/ml elicited an approximately 3-fold increase in GLUT1 mRNA levels. (Bu)2cAMP (1 mM), 8-bromo-cAMP (1 mM), and forskolin (50 microM) mimicked the effect of TSH on GLUT1 and GLUT4 mRNA levels. The increase in GLUT1 mRNA by TSH was correlated with the increase in GLUT1 protein and the increase in 2-deoxyglucose transport activity. These observations suggest that in thyroid cells, TSH stimulates glucose transport at least in part by enhancing GLUT1 gene expression, and that the effect of TSH on GLUT1 and GLUT4 mRNA levels is mediated by a cAMP-dependent pathway.

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Abstract. To clarify the effect of breed of recipient dams on the performance of calves produced by embryo transfer(ET), a total of 35 ET-calves were divided into 4 groups by the breed of recipient of Holstein-Friesian dams (HF), crossbred (Holstein×Japanese Black) dams (F1), Japanese Black dams (JB) and also JB dams without colostrum but received an artificial colostrum as a negative control (NC). Twenty calves produced by artificial insemination to JB dams were also provided as a positive control (PC). Calves in JB, HF, F1 and PC were placed with their dams for the first 7 days of age. Those in the NC group were kept in an individual pen. All calves were moved to individual pens on day 8, and were given the same commercial milk replacer. Calves were weaned at 61 days of age. Mean live weights at birth were not significantly different among groups except for calves of HF that were greater than other groups (p < 0.05). Mean daily gains also showed no significant differences among groups including PC and NC. All calves were in good healthy condition, which was also supported by changes in the level of blood parameters, irrespective of the breed of their dams. It is concluded that there was no appreciable effect of the breed of recipient dams on calf performance. The artificial colostrum powder feeding did not show any adverse effect on the performance of ET-calves, although serum protein and globulin tended to be lower.