- Email: [email protected]
Implantation of disulfiram in rats
83
triglyceride (TG). Possible involvement of several factors in the establishment of fatty liver such as increased peripheral fat mobilization and decreased hepatic lipolysis was also hypothesized. In the present study, we have examined the effect of short- and long-term administrations of ethanol to Std-ddY mice on hepatic lipogenesis, lipolysis in adipose tissues and the incorporation of fatty acids into hepatic TG. For short- and long-term administrations of ethanol, inhalation (3 days) and liquid diet (15 days) methods were employed, respectively. A significant increase of hepatic TG was induced by the short- and long-term administration of ethanol. A small increase in serum TG was also observed. On the other hand, the [ 14C] acetate incorporation into hepatic TG was not affected by the short-term administration, but increased significantly by the long-term administration. Similarly, the increase in fatty acid synthetase and malic enzyme activities in the liver was observed following the long-term administration, but not in animals treated by the short-term administration method. The activity of hepatic acetyl-CoA carboxylase, the rate-limiting step in fatty acid synthesis, also exhibited a significant increase following the long-term administration, but not in animals having the shortterm exposure to ethanol. The increase of [ i4C] palmitate incorporation in hepatic TG was observed in animals treated by the long-term as well as the short-term administration procedures. Lipoprotein lipase activity in adipose tissues showed an increase following the long- and short-term administration of ethanol, respectively. On the other hand, lipase activity and stimulatory effects of epinephrine and dibutyryl cyclic AMP on lipolytic activity in adipose tissues were not affected by these ethanol administrations. These results suggest that, in addition to enhancement of fatty acid synthesis in the liver, the mobilization of fatty acid from peripheral adipose tissues by activating lipoprotein lipase plays a significant role in the occurrence of fatty liver following prolonged administration of ethanol.
19
IMPLANTATION EWA HELLSTROM*,
OF DISULFIRAM OLOF TOTTMAR
IN RATS and RAINER
FRIED
Institute of Zoophysiology, University of Uppsala, Box 560, S-751 22 Uppsala (Sweden). and Department of Biochemistry, School of Aledicine, C’reighton University, Omaha, Nb: 68178 (U.S.A.)
Several clinical reports indicate a prolonged abstinence in patients receiving disulfiram implants. The pertinent question is whether the amounts of disulfiram released are sufficiently high to produce an alcohol-sensitizing effect. The dose of disulfiram implanted (1 g) corresponds to the usual oral dose given during less than one week. However, the mechanism underlying the alcohol-sensitizing effect of disulfiram is not fully understood, and,
24
therefore, no final conclusions can be drawn about the pharmacological efficacy of disulfiram implantation. In the present study, the biochemical and pharmacological effects of disulfiram implantation were studied in rats and compared to the effects obtained in rats receiving disulfiram orally or intraperitoneally. Sterile disulfiram pellets (2 X 100 mg) corresponding to a dose of 1000 mg/kg were implanted subcutaneously in the neck. Control rats were shamoperated. Groups of 5 rats were killed after 3, 7, 14, 28 and 56 days for analysis of pellet weight and enzyme activities. The release of disulfiram during the first week corresponded to a daily dose of 8 - 14 mg/kg and during the following period to 5 - 8 mg/kg. The activity of the low-R,, aldehyde dehydrogenase (ALDH) in the liver and the brain, and the dopamine fl-hydroxylase activity in the heart were significantly decreased by approx. 45, 35 and 35%, respectively, at all the observation days. The rate of ethanol elimination, the activity of monoamine oxidase in the brain, the content of cytochrome P-450 in the liver, and the levels of norepinephrine and dopamine in the brain were unaffected. The acetaldehyde level in blood after ethanol injection (1.0 g/kg) was 55 - 60 FM in the disulfiram group and 25 - 30 PM in the control group. The typical symptoms of the disulfiramethanol reaction (DER) (i.e. hypotension and tachycardia) were observed only in a few rats. Much more pronounced cardiovascular effects were found at similar acetaldehyde levels in rats pretreated for 24 h with a single oral or intraperitoneal dose of disulfiiam. In rats receiving a daily dose of 14 mg/kg orally during 7 days, the inhibition of the low-K, ALDH in the liver was similar to that found 7 days after the implantation of a dose of 1000 mg/kg. If similar conditions exist in humans, and if the classical explanation of the DER is accepted, this means that impractical large amounts of disulfiram have to be implanted in order to produce the alcohol-sensitizing effect obtained by oral administration. Supported Foundation.
by the Swedish MRC (Grant No. 04743) and the M. Bergwall
20 EFFECT OF PYRAZOLE AND 4-METHYLPYRAZOLE ON IN VW0 AND IN VITRO ACETALDEHYDE METABOLISM IN THE RAT D. R. PETERSEN*, Alcohol
Research
C. J. PETER ERIKSSON Center,
University
Pyrazole analogues inhibit the oxidation of More recently, pyrazole aldehyde dehydrogenase oxidases. In the present
and R. A. DEITRICH
of Colorado,
Boulder,
CO 80309
(U.S.A.)
have been used extensively in vitro and in uiuo to a wide range of alcohol dehydrogenase substrates. analogues have also been implicated as inhibitors of (ALDH), catalase and several mixed-function study, we have further explored the ability of
triglyceride (TG). Possible involvement of several factors in the establishment of fatty liver such as increased peripheral fat mobilization and decreased hepatic lipolysis was also hypothesized. In the present study, we have examined the effect of short- and long-term administrations of ethanol to Std-ddY mice on hepatic lipogenesis, lipolysis in adipose tissues and the incorporation of fatty acids into hepatic TG. For short- and long-term administrations of ethanol, inhalation (3 days) and liquid diet (15 days) methods were employed, respectively. A significant increase of hepatic TG was induced by the short- and long-term administration of ethanol. A small increase in serum TG was also observed. On the other hand, the [ 14C] acetate incorporation into hepatic TG was not affected by the short-term administration, but increased significantly by the long-term administration. Similarly, the increase in fatty acid synthetase and malic enzyme activities in the liver was observed following the long-term administration, but not in animals treated by the short-term administration method. The activity of hepatic acetyl-CoA carboxylase, the rate-limiting step in fatty acid synthesis, also exhibited a significant increase following the long-term administration, but not in animals having the shortterm exposure to ethanol. The increase of [ i4C] palmitate incorporation in hepatic TG was observed in animals treated by the long-term as well as the short-term administration procedures. Lipoprotein lipase activity in adipose tissues showed an increase following the long- and short-term administration of ethanol, respectively. On the other hand, lipase activity and stimulatory effects of epinephrine and dibutyryl cyclic AMP on lipolytic activity in adipose tissues were not affected by these ethanol administrations. These results suggest that, in addition to enhancement of fatty acid synthesis in the liver, the mobilization of fatty acid from peripheral adipose tissues by activating lipoprotein lipase plays a significant role in the occurrence of fatty liver following prolonged administration of ethanol.
19
IMPLANTATION EWA HELLSTROM*,
OF DISULFIRAM OLOF TOTTMAR
IN RATS and RAINER
FRIED
Institute of Zoophysiology, University of Uppsala, Box 560, S-751 22 Uppsala (Sweden). and Department of Biochemistry, School of Aledicine, C’reighton University, Omaha, Nb: 68178 (U.S.A.)
Several clinical reports indicate a prolonged abstinence in patients receiving disulfiram implants. The pertinent question is whether the amounts of disulfiram released are sufficiently high to produce an alcohol-sensitizing effect. The dose of disulfiram implanted (1 g) corresponds to the usual oral dose given during less than one week. However, the mechanism underlying the alcohol-sensitizing effect of disulfiram is not fully understood, and,
24
therefore, no final conclusions can be drawn about the pharmacological efficacy of disulfiram implantation. In the present study, the biochemical and pharmacological effects of disulfiram implantation were studied in rats and compared to the effects obtained in rats receiving disulfiram orally or intraperitoneally. Sterile disulfiram pellets (2 X 100 mg) corresponding to a dose of 1000 mg/kg were implanted subcutaneously in the neck. Control rats were shamoperated. Groups of 5 rats were killed after 3, 7, 14, 28 and 56 days for analysis of pellet weight and enzyme activities. The release of disulfiram during the first week corresponded to a daily dose of 8 - 14 mg/kg and during the following period to 5 - 8 mg/kg. The activity of the low-R,, aldehyde dehydrogenase (ALDH) in the liver and the brain, and the dopamine fl-hydroxylase activity in the heart were significantly decreased by approx. 45, 35 and 35%, respectively, at all the observation days. The rate of ethanol elimination, the activity of monoamine oxidase in the brain, the content of cytochrome P-450 in the liver, and the levels of norepinephrine and dopamine in the brain were unaffected. The acetaldehyde level in blood after ethanol injection (1.0 g/kg) was 55 - 60 FM in the disulfiram group and 25 - 30 PM in the control group. The typical symptoms of the disulfiramethanol reaction (DER) (i.e. hypotension and tachycardia) were observed only in a few rats. Much more pronounced cardiovascular effects were found at similar acetaldehyde levels in rats pretreated for 24 h with a single oral or intraperitoneal dose of disulfiiam. In rats receiving a daily dose of 14 mg/kg orally during 7 days, the inhibition of the low-K, ALDH in the liver was similar to that found 7 days after the implantation of a dose of 1000 mg/kg. If similar conditions exist in humans, and if the classical explanation of the DER is accepted, this means that impractical large amounts of disulfiram have to be implanted in order to produce the alcohol-sensitizing effect obtained by oral administration. Supported Foundation.
by the Swedish MRC (Grant No. 04743) and the M. Bergwall
20 EFFECT OF PYRAZOLE AND 4-METHYLPYRAZOLE ON IN VW0 AND IN VITRO ACETALDEHYDE METABOLISM IN THE RAT D. R. PETERSEN*, Alcohol
Research
C. J. PETER ERIKSSON Center,
University
Pyrazole analogues inhibit the oxidation of More recently, pyrazole aldehyde dehydrogenase oxidases. In the present
and R. A. DEITRICH
of Colorado,
Boulder,
CO 80309
(U.S.A.)
have been used extensively in vitro and in uiuo to a wide range of alcohol dehydrogenase substrates. analogues have also been implicated as inhibitors of (ALDH), catalase and several mixed-function study, we have further explored the ability of