Effects of Acute and Repeated Exposures to Aroclor 1254 in Adult Rats: Motor Activity and Flavor Aversion Conditioning

Abstract

demonstrate that Aroclor 1254 causes hypoactivity and flavor Effects of Acute and Repeated Exposures to Aroclor 1254 in aversions in adult rats; the no observable effect level (NOEL) for Adult Rats: Motor Activity and Flavor Aversion Conditioning. motor activity was 100 mg/kg for acute exposure and 10 mg/kg Nishida, N., Farmer, J. D., Kodavanti, P. R. S., Tilson, H. A., and for repeated exposure for a period of up to 6 weeks. Polychlorinated biphenyls (PCBs) have been identified as days old) were tested for motor activity in a photocell device after widespread environmental contaminants due to their extenacute (0, 100, 300, or 1000 mg/kg, po) or repeated (0, 1, 3, 10, 30 sive industrial use and persistence in the environment (Erickor 100 mg/kg/day, po, 5 days/week for 4 to 6 weeks) exposure to son, 1986). PCBs were commercially synthesized as mix- Most neurobehavioral studies have focused on the develwater deprived (30 min/day) and received acute po administration opmental neurotoxicity of PCBs. For example, it has been of Aroclor 1254 (0, 10, 15, 25, 30, 100, or 300 mg/kg) shortly after reported that exposure of mice, rats, and monkeys to PCBs consuming a saccharin solution. Three days later they were given during early development can adversely affect later behavthe choice between consuming saccharin or water, and saccharin ioral and cognitive function (Shiota, 1976; preferences were recorded. Saccharin preference was decreased at 1979;Bowman and Heironimus, 1981;Storm et al., 1981; doses of 25 mg/kg or more. Additional experiments determined Schantz et al., 1989). It has been suggested that PCB-induced the effect of repeated saccharin-Aroclor 1254 pairings (0, 3.75, developmental neurotoxicity may be caused by a thyroid 7.5, or 15 mg/kg/day, 14 days) followed by a choice test 1 day after hormone deficiency during a critical developmental period the last dose. Repeated exposure to 15 mg/kg produced robust (Porterfield, 1994). flavor aversion conditioning. Repeated exposure to 7.5 mg/kg produced flavor aversion conditioning in four of 12 rats. These resultsCompared to the effects of developmental PCB exposure, relatively little is known about the neurobehavioral effects of exposure to PCBs during adulthood, although some neuro-1 A part of this study was presented at the annual Society of Toxicology toxic signs such as numbness and weakness in the limbs meeting, March 1995 (Toxicologist 15, 189, 1995. This manuscript has were reported in human poisoning episodes (Kuratsune et al., results were inconclusive (Swanson et al., 1995). Acute ex-2

Effects of polychlorinated biphenyls on the nervous system

“…Assessment of motor coordination with two tests ( screen test and rotor rod ) did not reveal any significant effect 15 -120 min after treatment with a single dose of 500 mg / kg of Aroclor 1254. Similar results regarding a decrease in spontaneous motor activity were reported in adult male Long-Evans rats following single gavage doses of 300 mg / kg of Aroclor 1254; no significant effect was seen with 100 mg / kg ( Nishida et al, 1997 ). Incomplete recovery to pretreatment levels of activity occurred over a 9 -week period.…”

“…Kodavanti et al (1998 ) also reported decreased motor activity in adult male rats exposed to 30 mg / kg/day of Aroclor 1254 for 4 weeks. Nishida et al ( 1997) also conducted flavor-aversion conditioning tests and reported that the acute and repeated NOAELs for this behavioral test were 15 and 7.5 mg /kg, respectively. Freeman et al (2000 ) conducted a 52 -week feeding study in rats with various Aroclor mixtures ( 1016,1242,1254,1260 ) and found no significant treatment-related effects on a comprehensive number of neurological end points.…”

Aroclor 1254 alters morphology, survival, and gene expression in Xenopus laevis tadpoles

“…In addition, numerous studies have shown that PCBs cause alterations in motor behaviors in developing and adult mammals [Bowman et al, 1978;Chou et al, 1979;Nishida, 1997;Rosin and Martin, 1981;Schantz et al, 1991;Tilson et al, 1990].…”

“…PCBs cause a variety of adverse effects on the nervous system, including altered memory and learning, motor deficits, and neurodevelopmental delays [Brouwer et al, 1995;Nishida, 1997;Seegal et al, 1990;Stewart et al, 2000]. In addition, the dopaminergic neurotransmitter system, which plays an integral role in controlling motor behaviors, is altered by PCBs [Agrawal et al, 1981;Contreras, 1994, 1996;Bemis and Segal, 1999;Seegal et al, 1990].…”

Differential effects of two lots of aroclor 1254 on enzyme induction, thyroid hormones, and oxidative stress.

“…They were treated via oral gavage with corn oil (2 mL/kg). Dose levels were chosen based on the results of Nishida et al (26) because that experiment was conducted successfully using the more potent lot 6024. The doses for lot 124-191 were 0, 10, 30, 100, 300, or 1,000 mg/kg body weight, and the doses for lot 6024 were 0, 1, 3, 10, 30, 100, 300, or 1,000 mg/kg body weight.…”