Lipid synthesis by co-cultures of mammary, liver, and adipose tissue explants from sometribove (recombinant methionyl bovine somatotropin)-treated dairy cows
Tóm tắt
Bovine somatotropin was given to six lactating (230 day) cows (40 mg/day × 5-days) and excipient was given to six control cows. Mammary, liver, and adipose explants from somatotrophin and control cows were co-cultured at 37° C for 24 h with 0.5 µCi [14C]acetate/ml media with or without 0.5 µg/ml somatotrophin. Tissue lipids were extracted with chloroform/methanol and separated by thin layer chromatography. In vivo somatotrophin increased milk production 2.4 kg/day compared to a 0.9 kg/day decrease by controls. Mammary tissue from somatotrophin cows incorporated more [14C]acetate into total lipids (4417 vs. 3016 dpm/mg tissue) than controls. Adding somatotrophin to explant cultures from somatotrophin cows further increased incorporation into total lipids (4839 vs. 3994 dpm/mg tissue). In contrast, adipose tissue from somatotrophin cows incorporated less [14C]acetate into total lipids than controls (1524 vs. 2581 dpm/mg tissue). Serum IGF-I concentration correlated well (r=0.69) with milk output differences between Days 1 and 5 of treatment. Media IGF-I concentration correlated well (r=0.61) with the difference in total lipid synthesis between the in vitro control and somatotrophin groups. Results support the concept that somatotrophin increases milk production by partitioning nutrients away from adipose toward mammary tissue.
Tài liệu tham khảo
Bauman, D. E.; Eisemann, J. H.; Currie, W. B. Hormonal effects on partitioning of nutrients for tissue growth: role of growth hormone and prolactin. Fed. Proc. 41:2538–2544; 1982.
Binoux, M.; Lassarre, C.; Hardouin, N. Somatomedin production by rat liver in organ culture. III. Studies on the release of insulin-like growth factor and its carrier protein measured by radioligand assays. Effects of growth hormone, insulin and cortisol. Acta Endocrinol. 99:422–430; 1982.
Bitman, J.; Wood, D. L. Quantitative densitometry in situ of lipids separated by thin layer chromatography. J. Liquid Chromat. 4:1023–1034; 1981.
Bitman, J.; Wood, D. L. An improved copper reagent for quantitative densitometric thin-layer chromatography of lipids. J. Liquid Chromatogr. 5:1155–1162; 1982.
Bitman, J.; Wood, D. L.; Ruth, J. M. Two-stage, one dimensional thin layer chromatographic method for separation of lipid classes. J. Liquid Chromatogr. 4:1007–1021; 1981.
Bitman, J.; Wood, D. L.; Hamosh, M., et al. Comparison of the lipid composition of breast milk from mothers of term and preterm infants. Am. J. Clin. Nutr. 38:300–312; 1983.
Bitman, J.; Wood, D. L.; Tyrrell, H. F., et al. Blood and milk lipid responses induced by growth hormone administration in lactating cows. J. Dairy Sci. 67:2873–2880; 1984.
Brumby, P. J.; Hancock, J. The galactopoietic role of growth hormone in dairy cattle. N. Z. J. Sci. Tech. A36:417–436; 1955.
Capuco, A. V.; Keys, J. E.; Smith, J. J. Somatotrophin increases thyroxine-5′-monodeiodinase activity in lactating mammary tissue of the cow. J. Endocrinol. 121:205–211; 1989.
Disenhaus, C.; Belair, L.; Djiane, J. Characterisation et evolution physiologique des recepteurs pour les ≪ insulin-like growth factors ≫ I et II (IGFs) dans la glande mammaire de brebis. Reprod. Nutr. Dev. 28:241–252; 1988.
Fekry, A. E.; Keys, J. E.; Capuco, A. E., et al. Effect of bovine growth hormone on incorporation of [14C]acetate into lipids by co-cultures of bovine mammary, liver, and adipose tissue explants. Dom. Anim. Endocrinol. 6:87–94; 1989.
Folch, J.; Lees, M.; Sloane-Stanley, G. H. A simple method for the isolation and purification of total lipids from animal tissues. J. Biol. Chem. 226:497–509; 1957.
Gertler, A.; Cohen, N.; Maoz, A. Human growth hormone but not ovine or bovine growth hormone exhibits galactopoietic prolactin-like activity in organ culture from bovine lactating mammary gland. Mol. Cell. Endocrinol. 33:169–182; 1983.
Glimm, D. R.; Baracos, V. E.; Kennelly, J. J. Effect of bovine somatotrophin on the distribution of immunoreactive insulin-like growth factor-I in lactating bovine mammary tissue. J. Dairy Sci. 71:2923–2935; 1988.
Goodman, G. T.; Akers, R. M.; Friderici, K. H., et al. Hormonal regulation of alpha-lactalbumin secretion from bovine mammary tissue cultured in vitro. Endocrinology 112:1324–1330; 1983.
Hart, I. C.; Bines, J. A.; James, S., et al. The effect of injecting or infusing low doses of bovine growth hormone on milk yield, milk composition and the quality of hormone in the blood serum of cows. Anim. Prod. 40:243–250; 1985.
Keys, J. E.; Djiane, J. Somatotropic and lactogenic binding sites in mammary and liver tissue of lactating cows. J. Recept. Res. 8:731–750; 1988.
Machlin, L. J. Effect of growth hormone on milk production and feed utilization in dairy cows. J. Dairy Sci. 56:575–580; 1973.
Peel, C.; J.; Fronk, T. J.; Bauman, D. E., et al. Effects of exogenous growth hormone in early and late lactation on lactational performance of dairy cows. J. Dairy Sci. 66:776–782; 1983.
Schalch, D. S.; Heinrich, U. E.; Draznin, B., et al. Role of the liver in regulating somatomedin activity: hormonal effects on the synthesis and release of insulin-like growth hormone factor and its carrier protein by the isolated perfused rat liver. Endocrinology 104:1143–1151; 1979.
Statistical Analysis System. SAS Users Guide: Statistics. Cary, NC: SAS Institute, Inc.; 1982.