Preface This second issue of the Toxicologist is devoted exclusively to the abstracts of the platform and poster sessions of the 21st Annual Conference of the Society of Toxicology, held at the Sheraton-Boston Hotel, Boston, MA, February, 22-26, 1982. The abstracts are reproduced, without editing, as accepted by the Program Committee of the Society of Toxicology, and appear in the same numerical sequence as the papers appear in the Conference's official program. An alphabetical author index, listing the corresponding paper number, appears on pp. 194. Copies of this issue are available at $5 each (U.S. funds) from Society of Toxicology 475 Wolf Ledges Parkway Akron, OH 44311-1087 ® 1982, Society of Toxicology 1 BUTYLATEDHYDROXYTOLUENE DOES NOT INHIBIT CIPRO­ ment of a 6-MC protein or amino acid adduct in FIBRATE AND DI-(2-ETHYLHEXYL)PHTHALATEINDUCED 6-MC photoallergenicity. (Supported in part by PEROXISOMEPROLIFERATION IN RAT LIVER. N.D. the Research Institute for Fragrance Materials). Lalwani, H. Hayashi, M.K. Reddy, C. Moehle, and ) J.K. Reddy, Dept. Pathol., Northwestern Univ. Med. Sch., Chicago, IL. 3 ALTERATIONOF CALCIUM-DEPENDENTGABARELEASE AND Evidence now suggests that hepatic peroxisome THEENZYME ACTIVITIES OF GLUTAMICACID DECARBOXY­ proliferators as a class are carcinogenic. It is LASE(GAD) AND GABA-y-KETOGLUTARATE TRANSAMINASE hypothesized that persistant proliferation of (GABA-T)IN RESPONSETO THEACUTE AND CHRONIC AD­ peroxisomes and increase in peroxisomal S-oxida­ MINISTRATIONOF PHENCYCLIDINE(PCP). J. C. Norris, tion initiates the neoplastic transformation of T. Nabeshima, S. P. Sivam and I. K. Ho, Dept. liver cells by increasing the intracellular pro­ Pharmacol. & Toxicol., Univ. MSMed. Ctr., Jack­ duction of DNA-damaging H202 and other reactive son, MS 39216. oxygen intermediates. In the present study we have investigated the effect of antioxidant buty­ The involvement of GABAergicsystem with acute lated hydroxytoluene (BHT) to determine whether and chronic PCP administration was investigated free radical scavanging antioxidant could inhibit by noting alterations in calcium-dependent GABA peroxisome proliferation induced by hypolipidemic release in mouse brain slices and the activity of drug ciprofibrate (2,-[4-{2,2-dichlorocyclopro­ the enzymes, GADand GABA-T,of the whole mouse pyl}-phenoxy]2-methyl propionic acid) and DEHP. brain. The chronic administration of PCP for the Ciprofibrate at 0.1% concentration in diet in­ release study was accomplished by osmotic mini­ creased peroxisomal enzyme activities in livers pumps at a rate of 1 mg/day. The GABArelease of male F344 rats. Simultaneous feeding of BHT for the chronic animal in both the striatal and at either 7000 ppm or 700 ppm in diet did not in­ cerebellar slices was decreased while the time of hibit the peroxisome proliferation and peroxisomal the change was different for the two discrete enzyme activities inducible by ciprofibrate. areas. The striatal slices returned to the con­ trol values after 4 and 6 days of continuous ad­ Similarly, BHT failed to inhibit DEHP induced per­ ministration whereas the cerebellum slices were oxisome proliferation in rat liver. Additional decreased only in the 4-day treatment group. The studies are required to ascertain whether BHT tissues of acutely treated mice responded in a inhibits the peroxisome proliferator induced manner dependent on the dosage level. The low carcinogenesis in rat liver. Supported by NIH dose (10 mg/kg) of PCP increased ca++-dependent grant GM 23750. GABArelease in striatum. The high dose (40 mg/ kg) of PCP, however, demonstrated a decrease in GABArelease in striatum. The enzyme activities of GADand GABA-Twere measured in animals which 2 A MECHANISMFOR 6-METHYLCOUMARINPHOTOALLER­ received 40 mg/kg, i.p., once daily for five days. GENICITY. M.W.Tabor, S. Kato, M. Ohno and R.R. The chronically PCP treated animals demonstrated Suskind, Dept. of Environ. Hlth, Univ. of Cin­ a significant increase in GADand GABA-Tlevels. cinnati Med. Ctr., Cincinnati, OH. Sponsor: The acutely PCP treated animals showed a decrease Dr. C. C. Smith. in the GADactivity and no change in the GABA-T activity. Thus, it seems that the GABAergicsys­ Photoallergic dermatitis and allergic hypersen­ tem is altered by the presence of PCP. (Supported sitivity have been reported in persons using by research grant DA-01310from NIDAand toxicol­ commercial products containing 6-methylcoumarin ogy training grant ES-07045 from NIEHS) (6-MC) as a fragrance material. The purpose of our study was to investigate the biochemical basis of the photoallergic reactions of 6-MC. We have examined the ultraviolet (UV) catalyzed 4 DRUGMETABOLIZING EN2YMES IN C3HlOT½ CELLS photochemical reactions of 6-MC with representa­ EXPOSEDTO POLYCHLORINATEDBIPHENYLS (PCBs). tive amino acids (lys, ser, gly, glu, cys, met, H.P. Cihla, G, Reddy, & D.R. Norback. Depart­ phe, tyr, and trp) and glutathione (GSH) under ments of Pathology, William S. Middleton Mem­ physiological conditions. These reactions were orial Veterans' Hospital and the University of used to model the photochemical reactions of Wisconsin, Madison, Wisconsin, 53705. 6-MC with proteins. The source of UV light We have shown the cytotoxic and oncogenic catalysis was either UVA of wavelengths from effects of certain technical PCBs and PCB an­ 310 nm to 400 nm or UVB of wavelengths from alogues on the C3Hl0T½ cell system. In order 280 nm to 370 nm. Samples were exposed for 1, to define possible mechanisms of pathologic 12 or 24 hrs, and then reaction products were change, we studied basal drug metabolizing en­ isolated by either silica gel TLC or sequential zyme activities of this cell line and th re­ extraction using a series of nonpolar to polar sponse to Aroclor 1260. Cells (1.5 x 10)5 were solvents followed by silica gel TLC of the ex­ plated in T-75 flasks and, 24 hours later, were tracts. UVA was a more potent catalyst than continuously exposed to either 10 ppm PCB or 1% UVB for all reactions studied. For 6-MC alone, acetone. On 6, 10 or 15 days, cells were col­ the UV reaction yielded three products at 12 lected and microsomal and cytosolic fractions and 24 hrs. The production of the least polar were prepared. The specific activities of mi­ of these products was quenched by cys and GSH. crosomal styrene oxide epoxide hydrolase (EH), For the reactions of 6-MC with amino acids and cytosolic glutathione S-epoxide transferase (GT) GSH, the UV reactions appeared to produce 6-MC and microsomal P-450-associated aldrin epoxidase photoconjugates with lys, cys, and GSH, and to a (AE) were assayed. Six day cultures de-111onstrated lesser degree with tyr, ser, trp and phe. Gly, basal activity for AE (4.3 pmole dieldrin/mg of glu and met appeared to be unreactive. The re­ protein/30 minutes). Basal levels of EH and GT sults of this study clearly suggest the involve- from preconfluent cultures (1.51 +/- 0.38 and 14.20 +/- 1.17 nrnole/mg/min, respectively) de­ reduced in the presence of the membrane­ clined approximately 50% after confluence had stabilizing agents triamcinolone and been reached (day 15). Exposure to PCB produced chlorpromazine. no change in EH activity at any of the time Supported by NIH Biomedical Grant 363183-4. points. However, GT activity increased approxi­ mately 50% in preconfluent cultures (days 6 and 10) and approximately 10% in postconfluent cul­ 7 ANAEROBICACTIVATION OF CHLORAMPHENICOLBY RAT tures. These enzymes may play a role in the LIVER MICROSOMES.P.L. Morris, T.R. Burke and metabolism of PCBs and, thus, may alter the L.R. Pohl, NHLBI, Bethesda, MD,: Sponsor: effects of PCBs on this cell culture system. J.R. Gillette. (Supported by the Veterans' Administration, NIH Chloramphenicol (CAP, RNHCOCHClz)has previous­ grant CA 22140 and ACS grant IN-35-4.) ly been shown to be activated by rat liver cyto­ chrome P-450 aerobically to an oxamyl chloride (RNHCOCOCl)that either covalently bonded to 5 THEEFFECT OF ASCORBICACID ON COPPER AND microsomal protein (RNHCOCO-protein) or reacted NITRITE-INDUCEDOXIDATIVE CHANGES IN with water to form CAP oxamic acid (RNHCOCOOH). ERYTHROCYTES:INTERSPECIES DIFFERENCES. In the present study we have found that rat E.J. Calabrese, G.S. Moore and M. McCarthy, liver cytochrome P-450 also activates CAP an­ Division of Public Health, University of aerobically by another mechanism. When a mix­ Massachusetts, Amherst, MA. ture of 3H-(benzylic position) and 14c(dichloro­ Ascorbic acid incubation with human acetamido carbons) labeled CAP (0,1 mM) were erythrocytes markedly reduced the occurrence incubated anaerobically with rat liver micro­ of sodium nitrite induced methemoglobin in a somes (2 mg/ml) from phenobarbital (PB) pre­ dose dependent fashion. In marked contrast, treated rats and a NADPHgenerating system, both ascorbic acid incubation with Dorset sheep labels were bound irreversibly to microsomal erythrocytes treated with sodium nitrite did protein to approximately the same amount (330 not have any effect on the occurrence of pmol/mg protein/30 min) and monodeschloro-CAP sodium nitrite induced methemoglobin (DCl-CAP, RNHCOCH2Cl, 1228 pmol/mg protein/30 formation. min) was formed, Under these reaction condi­ Using an identical in vitro experimental tions, no nitro-reduction products of CAP were protocol as with the nitrite experiments, detected. The formation of covalently bonded ascorbic acid was found to markedly enhance product and DCl-CAP were decreased by over 70% the occurrence of copper induced oxidative when the incubations were conducted in the pre­ stress (i.e. increasing methemoglobin levels) sence of SKF 525A (0.5 mM), CO (100%) or in the in both sheep and humans. absence of an NADPHgenerating system. Moreover, less than 10% as much covalently bound product and DCl-CAP was detected when microsomes from control rats or rats pretreated with s-naphtho­ 6 BIOCHEMICAL TOXICITY IN MICE OF SUB­ flavone were used, These results suggest that a STANCES PRODUCED BY ctostridium difficile.