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Effects of toxic compounds on olfaction
NEUROBEHAVIORAL
TERATOLOGY
SOCIETYABSTRACTS
NBTS 12 HASTINGS, L., Department of Environmental Health, University of Cincinnati, Cincinnati, Ohio. Effects of toxic compounds on olfaction. Few studies have examined olfactory function after exposure to toxic compounds which target the nasal cavity. We have found in rats that exposure to cadmium and nickel, compounds which are purported to cause olfactory dysfunction in humans, resulted in few effects either in terms of cytotoxicity or alterations in function. Methyl bromide produced extensive damage to the olfactory epithelium, but only transient alterations in function. Only when there was damage to the Bowman's glands have long term deficits in function been osberved. However, in order to produce such damage, compounds such as 3-methyl indole or dichlobenil must be administered systemically. The generality of these findings is limited by the small number of compounds that have been tested, as well as the relative specificity of the evaluation techniques. The relevance of these findings to humans can also be questioned since the rat is macrosmatic, while man is microsmatic. Although the human olfactory system appears to be less resilient to toxic insult than the rodent's, human experimental data concerning these issues are very limited. Supported by NIEHS Grant ES-04099
NBTS 13 LAUGHLIN, N.K., The Harlow Center for Biological Psychology, The University of Wisconsin, Madison, WI. Lead effects on the auditorv svstem. The effects of low level lead exposure range from global behavioral abnormalities such as IQ, cognitive, and attentional deficits to specific sensory disorders. However, the sensory abnormalities are less extensively characterized and their role in the broader disorders is not well understood. A review of the literature on susceptibility of the auditory system to lead indicates effects on hearing threshold, the VIIIth
331
nerve and multiple components of auditory brain stem evoked response (ABR). Electrophysiological indices of speech perception also are affected, and behavioral measures of complex auditory processing such as speech perception, language comprehension and auditory memory are impaired. Lead effects on specific attentional processes within the auditory system may underlie some of these effects. Studies from this lab have examined lead effects on auditory system function in the rhesus monkey as an animal model of childhood lead exposure. Effects of early, chronic exposure were observed in adulthood on the ABR collected under a variety of stimulus conditions and on distortion product otoacoustic emissions, an index of cochlear function. Behavioral evaluations of thresholds over a broad range of frequencies indicated lead effects at only very high frequencies. However, other behavioral responses collected in this task revealed lead effects on attention. Lead appears to impact on the auditory system at multiple levels of the auditory pathway. Supported by ROl ES04860
NBTS 14 DOW-EDWARDS, D.L., FRICK, G.S and YIN, R. Department of Pharmacology, State University of New York, Brooklyn, NY Context-dependent effects of developmental cocaine exnosure. An apparently insurmountable hurdle in the understanding of the developmental neurotoxicity of cocaine is reproducibility of findings across labs. Data from our lab may address this issue since we have found that changes in brain glucose metabolism depend on the environmental conditions in which the animal is studied, a concept which is not new to most experimental psychologists. We used the deoxyglucose method to determine functional activity and found that preweaning cocaine administration stimulates metabolism in many brain regions in adult females examined on the lab bench (Dev. Brain Res. 72:309, 1993). However, if the animals are habituated to small tents which restrict their movement and attenuate sensory stimulation, rates of metabolism are reduced in many of the same limbic relay nuclei showing stimulation when assessed under normal conditions. Therefore, our data support the hypothesis that preweaning cocaine exposure alters the range of functional activity which the nervous system expresses. The animals may be
TERATOLOGY
SOCIETYABSTRACTS
NBTS 12 HASTINGS, L., Department of Environmental Health, University of Cincinnati, Cincinnati, Ohio. Effects of toxic compounds on olfaction. Few studies have examined olfactory function after exposure to toxic compounds which target the nasal cavity. We have found in rats that exposure to cadmium and nickel, compounds which are purported to cause olfactory dysfunction in humans, resulted in few effects either in terms of cytotoxicity or alterations in function. Methyl bromide produced extensive damage to the olfactory epithelium, but only transient alterations in function. Only when there was damage to the Bowman's glands have long term deficits in function been osberved. However, in order to produce such damage, compounds such as 3-methyl indole or dichlobenil must be administered systemically. The generality of these findings is limited by the small number of compounds that have been tested, as well as the relative specificity of the evaluation techniques. The relevance of these findings to humans can also be questioned since the rat is macrosmatic, while man is microsmatic. Although the human olfactory system appears to be less resilient to toxic insult than the rodent's, human experimental data concerning these issues are very limited. Supported by NIEHS Grant ES-04099
NBTS 13 LAUGHLIN, N.K., The Harlow Center for Biological Psychology, The University of Wisconsin, Madison, WI. Lead effects on the auditorv svstem. The effects of low level lead exposure range from global behavioral abnormalities such as IQ, cognitive, and attentional deficits to specific sensory disorders. However, the sensory abnormalities are less extensively characterized and their role in the broader disorders is not well understood. A review of the literature on susceptibility of the auditory system to lead indicates effects on hearing threshold, the VIIIth
331
nerve and multiple components of auditory brain stem evoked response (ABR). Electrophysiological indices of speech perception also are affected, and behavioral measures of complex auditory processing such as speech perception, language comprehension and auditory memory are impaired. Lead effects on specific attentional processes within the auditory system may underlie some of these effects. Studies from this lab have examined lead effects on auditory system function in the rhesus monkey as an animal model of childhood lead exposure. Effects of early, chronic exposure were observed in adulthood on the ABR collected under a variety of stimulus conditions and on distortion product otoacoustic emissions, an index of cochlear function. Behavioral evaluations of thresholds over a broad range of frequencies indicated lead effects at only very high frequencies. However, other behavioral responses collected in this task revealed lead effects on attention. Lead appears to impact on the auditory system at multiple levels of the auditory pathway. Supported by ROl ES04860
NBTS 14 DOW-EDWARDS, D.L., FRICK, G.S and YIN, R. Department of Pharmacology, State University of New York, Brooklyn, NY Context-dependent effects of developmental cocaine exnosure. An apparently insurmountable hurdle in the understanding of the developmental neurotoxicity of cocaine is reproducibility of findings across labs. Data from our lab may address this issue since we have found that changes in brain glucose metabolism depend on the environmental conditions in which the animal is studied, a concept which is not new to most experimental psychologists. We used the deoxyglucose method to determine functional activity and found that preweaning cocaine administration stimulates metabolism in many brain regions in adult females examined on the lab bench (Dev. Brain Res. 72:309, 1993). However, if the animals are habituated to small tents which restrict their movement and attenuate sensory stimulation, rates of metabolism are reduced in many of the same limbic relay nuclei showing stimulation when assessed under normal conditions. Therefore, our data support the hypothesis that preweaning cocaine exposure alters the range of functional activity which the nervous system expresses. The animals may be