Behavioral responses to methylphenidate and apomorphine in rats exposed neonatally to bisphenol-A.
Neonatal exposure of rats to bisphenol-A, an endocrine disruptor, has recently been proposed as a possible animal model of attention-deficit hyperactivity disorder, because such rats exhibit motor hyperactivity and impaired habituation to a novel environment 4-5 weeks after bisphenol-A pretreatment. To extend the original experiments, the present study additionally analyzed the effects of neonatal exposure to bisphenol-A (20 and 40 microg) on rat habituation to a novel environment and drug-induced behavior particularly at a later stage after bisphenol-A pretreatment. Single intracisternal administration of bisphenol-A (20 microg) into 5-day-old male Wistar rats did not cause any significant changes in habituation, as assessed in terms of locomotor activity, rearing, sniffing and grooming in rats at 8 weeks of age. Methylphenidate (1 and 3 mg/kg, i.p.), a psychostimulant, dose-dependently enhanced locomotor activity in both vehicle- and bisphenol-A (20 microg)-pretreated rats at 8 weeks of age, whereas other behaviors, i.e. rearing, sniffing and grooming, were not significantly affected. Additional challenge with apomorphine (1 mg/kg, i.v.), a dopamine receptor agonist, in vehicle- and bisphenol-A (20 and 40 microg)-pretreated rats at 10 weeks of age elicited a similar level of repetitive jaw movements measured by a magnet-sensing system under freely moving conditions during both the dark and the light phases. Thus, the effects of apomorphine did not differ between bisphenol-A-pretreated and vehicle-pretreated rats. It is concluded that, though some behavioral changes are evident in rats at an early stage (4-5 weeks) after neonatal treatment with bisphenol-A, the pretreatment does not induce any behavioral changes in habituation to a novel environment or in response to methylphenidate and to apomorphine at a later stage (8-10 weeks).
Kiguchi
Motori
M
Department of Orthodontics, Nihon University School of Dentistry, Tokyo, Japan.
Fujita
Satoshi
S
Lee
Jun
J
Shimizu
Noriyoshi
N
Koshikawa
Noriaki
N
D000818:Animals; D000831:Animals, Newborn; D001058:Apomorphine / Q000008:administration & dosage / Q000494:pharmacology*; D001289:Attention Deficit Disorder with Hyperactivity; D001522:Behavior, Animal / Q000187:drug effects*; D001559:Benzhydryl Compounds; D002946:Cisterna Magna; D018491:Dopamine Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D018765:Dopamine Uptake Inhibitors / Q000008:administration & dosage / Q000494:pharmacology*; D004968:Estrogens, Non-Steroidal / Q000008:administration & dosage / Q000494:pharmacology*; D005106:Exploratory Behavior / Q000187:drug effects; D007274:Injections, Intraperitoneal; D007568:Jaw / Q000187:drug effects / Q000502:physiology; D008297:Male; D008774:Methylphenidate / Q000008:administration & dosage / Q000494:pharmacology*; D023421:Models, Animal; D009043:Motor Activity / Q000187:drug effects*; D010636:Phenols / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D000098826:Bisphenol A Compounds
D001058:Apomorphine; D001559:Benzhydryl Compounds; D018491:Dopamine Agonists; D018765:Dopamine Uptake Inhibitors; D004968:Estrogens, Non-Steroidal; D008774:Methylphenidate; D010636:Phenols; C006780:bisphenol A; D000098826:Bisphenol A Compounds