Stearoyl-CoA desaturase (delta 9-desaturase) activity was measured in chicken primary hepatocytes, as a function of time in culture. 2. When using fasted donor animals, the desaturase activity was low at the beginning of culture and then increased steadily to a maximum value between 30 and 70 hr of culture. When hepatocyte cultures were prepared from fed animals, enzyme activity was high at the beginning of culture and maintained thereafter at similar values to those obtained in cultured hepatocytes from fasted animals after 30 hr of culture. 3. Insulin significantly enhanced enzyme activity when added to the culture medium at a 10(-9) M concentration, and a small stimulating effect was also observed with 10(-6) M dexamethasone. 4. Linoleic acid (0.5 mM) added to the culture medium as albuminic complex partly inhibited delta 9-desaturase activity. 5. Cordycepin (3' deoxyadenosine) decreased enzyme activity when present at a 3 micrograms/ml concentration in the culture medium. 6. Taken together, the induction of enzyme activity in culture, its impairment by cordycepin and response to insulin and linoleic acid strongly suggest that synthesis and translation of the delta 9-desaturase mRNA occur in chicken hepatocytes in primary culture, and that this cellular model may be a useful tool for further studies on delta 9-desaturase regulatory mechanisms.
