AMOUNT AND TYPE OF DIETARY-LIPID MODULATE RAT HEPATIC CYTOCHROME-P-450 ACTIVITY

The influence of the amount and type of dietary lipid on rat hepatic c ytochrome P-450 activities in the presence and absence of inducer admi nistration was investigated. Weanling male Sprague-Dawley rats were fe d fat-free or 20% beef tallow, olive oil, corn oil, linseed oil, or me nhaden oil diets in combination with one of the following three treatm ents: no inducer, intraperitoneal injection of phenobarbital (75 mg/kg body wt) for three consecutive days before they were killed, or intra gastric administration of acetone (5 ml/kg) one day before they were k illed. Twenty percent linseed oil and menhaden oil diets induced the h ighest level of activity among the different fat types in the presence of phenobarbital and acetone. Cytochrome P-450IIB1 activity was induc ed to a significantly greater extent by acetone administration in conj unction with the 20% menhaden oil diet than in conjunction with the ot her dietary oils (p < 0.05). In the presence of acetone, 20% beef tall ow, 20% linseed oil, and 20% menhaden oil diets significantly induced cytochrome P-450IIE1 activity compared with the fat-free diet (p < 0.0 5). In conclusion, cytochrome P-450IIB1 and P-450IIE1 activities in ra ts were significantly increased by specific inducers, and dietary lipi d was necessary for this effect. Diets supplemented with linseed and m enhaden oils were most effective in inducing this activity.