Qualitative effects of dioxin on molars vary among inbred mouse strains.
OBJECTIVE
We evaluated the effects of different levels of the potent environmental toxicant and teratogen, 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), on molar development in mice in six inbred strains, all with TCDD responsive Ahr alleles.


METHODS
Pregnant females were exposed on gestation day 13 to 4 different levels of TCDD (control, 0.01, 0.1 and 1.0 microg/kg) and their offspring were examined for the frequency of missing third molars (M3s) and for differences in first mandibular molar (M1) cuspal morphology.


RESULTS
Missing M3s were prevalent only in mice in two strains, C3H/HeJ and CBA/J, and their frequency significantly increased with increasing TCDD exposure. The frequency of the M1 variant was high in mice in only one strain, C57BL/10J, and was significantly higher in the treated compared with the control group.


CONCLUSIONS
Inbred mice strains exhibited differential responses to TCDD suggesting that there is a genetic component, beyond Ahr differences, mediating the effects of TCDD on molar development.
Keller
J M
JM
Department of Biology, University of North Carolina at Charlotte, Charlotte, North Carolina 28223-0001, USA. jmkeller@email.uncc.edu
Huet-Hudson
Y M
YM
Leamy
L J
LJ
D000483:Alleles; D000818:Animals; D000848:Anodontia / Q000139:chemically induced; D051792:Basic Helix-Loop-Helix Proteins; D004781:Environmental Exposure; D004785:Environmental Pollutants / Q000633:toxicity*; D005260:Female; D005865:Gestational Age; D008297:Male; D051379:Mice; D008805:Mice, Inbred A; D008807:Mice, Inbred BALB C; D008809:Mice, Inbred C3H; D008810:Mice, Inbred C57BL; D008808:Mice, Inbred CBA; D008815:Mice, Inbred Strains; D008963:Molar / Q000002:abnormalities* / Q000187:drug effects; D008964:Molar, Third / Q000002:abnormalities / Q000187:drug effects; D009805:Odontogenesis / Q000187:drug effects; D000072317:Polychlorinated Dibenzodioxins / Q000633:toxicity*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D018336:Receptors, Aryl Hydrocarbon / Q000187:drug effects / Q000235:genetics; D013723:Teratogens / Q000633:toxicity*; D019228:Tooth Crown / Q000002:abnormalities / Q000187:drug effects
D051792:Basic Helix-Loop-Helix Proteins; D004785:Environmental Pollutants; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon; D013723:Teratogens; C484722:Ahr protein, mouse