Development of glucogenesis from galactose by fetal rat liver explants in organ culture

Basic parameters of net glucose and net galactose uptake by fetal rat liver explants at 16 and 20 days of gestation (term = 21-22 days) remained relatively constant over 3 days in a defined organ culture system. Explants at 20 days of gestation released glucose into the culture medium in proportion to the varied medium galactose concentrations (0 to 20 mM); explants at 16 days of gestation lacked this glucogenic response. When 16-day explants were exposed to glucocorticoids (triamcinolone, dexamethasone, or corticosterone) during culture, there was a time- and concentration-dependent development of glucose production from galactose. The precocious development of galactose glucogenesis could be reproduced in utero by the interperitoneal injection of 0.4 mg of dexamethasone into mothers on Days 14 and 15 of gestation. Such 16-day explants from fetuses of dexamethasone-treated mothers exhibited a further increase in the magnitude of glucose released when they were exposed to additional glucocorticoids in culture. Other steroid hormones (progesterone, estradiol, and testosterone) as well as glucagon had no effect on the development of this response.