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Gestational-lactational exposure to Aroclor 1254 impairs radial-arm maze performance in male rats
C S Roegge1, B W Seo, K M Crofton
1Neuroscience Program, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Insights
Perinatal exposure to Aroclor 1254 (A1254) impaired spatial learning and memory in male rats but not females. This suggests sex-specific cognitive deficits following developmental exposure to polychlorinated biphenyls (PCBs).
Area of Science:
- Neuroscience
- Toxicology
- Developmental Biology
Background:
- Developmental exposure to polychlorinated biphenyls (PCBs) is linked to cognitive deficits.
- Aroclor 1254 (A1254) is a commercial PCB mixture.
- Spatial learning and memory are crucial cognitive functions.
Purpose of the Study:
- To assess the effects of gestational and lactational A1254 exposure on spatial learning and memory in rats.
- To investigate potential sex-specific differences in PCB-induced cognitive impairment.
- To examine the role of NMDA and muscarinic neurotransmission in A1254-exposed rats.
Main Methods:
- Pregnant Long-Evans rats were exposed to 0 or 6-mg/kg/day A1254 from gestation day 6 to postnatal day 21.
- Offspring were tested on a 12-arm radial-arm maze (RAM) for working and reference memory.
- Drug challenges with dizocilpine (MK-801) and scopolamine were administered.
Main Results:
- A1254-exposed male rats exhibited significantly more working and reference memory errors on the RAM compared to controls.
- A1254-exposed female rats showed no significant impairment in spatial learning and memory.
- Drug challenges did not differentially affect memory performance between control and A1254-exposed rats.
Conclusions:
- Perinatal A1254 exposure induces sex-specific deficits in spatial learning and memory in rats.
- Male rats are more susceptible to A1254-induced spatial memory impairments.
- NMDA-mediated and muscarinic neurotransmission appear unaffected by developmental A1254 exposure at the tested doses.
Abstract:
Developmental exposure to polychlorinated biphenyls (PCBs) has been associated with cognitive deficits in children. The current study assessed effects of gestational and lactational exposure to a commercial PCB mixture, Aroclor 1254 (A1254), on spatial learning and memory in rats, using the radial-arm maze (RAM). Pregnant Long-Evans females (10/dose group) were exposed to 0 or 6-mg/kg/day A1254 (po in corn oil) from gestation day (GD) 6 to weaning at postnatal day (PND) 21. After they reached adulthood, 1 male and 1 female from each litter were tested on a working/reference memory task using a 12-arm RAM. Eight of the 12 arms were baited, with the pattern of baited arms remaining the same on every trial for each rat. Compared to control males, the A1254-exposed males made significantly more working memory errors (2.15 +/- 0.13 and 3.20 +/- 0.18 errors +/- SEM for control and A1254 males, respectively) and reference memory errors (3.17 +/- 0.10 and 4.13+/-0.14 errors +/- SEM for control and A1254 males, respectively) on the RAM. In contrast, A1254-exposed females were not impaired relative to control females on the RAM. Drug challenges with dizocilpine (MK-801) and scopolamine did not differentially affect working or reference memory of control and exposed rats. These data suggest that perinatal exposure to A1254 may cause sex-specific deficits in spatial learning and memory, and that NMDA-mediated and muscarinic neurotransmission, as assessed with the drug challenges, were not markedly impaired in the A1254-exposed animals.
