title: Prenatal phenytoin exposure and spatial navigation in offspring: effects on reference and working memory and on discrimination learning.
abstract: Previous research has shown that rats exposed to phenytoin (PHT) in utero demonstrate abnormal circling, decreased learning, hyperactivity, and delayed air righting reflex development. The effects of prenatal PHT on offspring learning have been found on multiple-T mazes (Biel and Cincinnati types) and on spatial navigation (Morris maze). However, the specificity of the latter effects is unknown. Herein, we tested the effects of prenatal PHT in a Morris maze using six different procedures: cued versus spatial reference memory-based learning, cued versus spatial working memory-based learning, and cued versus spatial discrimination learning. PHT-exposed offspring showed increased preweaning mortality, growth reduction, and abnormal circling as noted in previous studies. PHT offspring were separated into those exhibiting circling and those not. PHT noncircling offspring demonstrated impaired reference memory-based spatial learning (acquisition and reversal), but no other effects. By contrast, PHT circling offspring demonstrated not only impaired reference memory-based spatial learning, but also impaired cued platform learning, impaired spatial discrimination, and impaired working memory-based learning. These data confirm that prenatal PHT induces a specific reference memory-based spatial learning deficit even in asymptomatic (noncircling) offspring that is distinct from the impairment induced in littermates exhibiting the circling impairment.
authors.affiliation: Division of Developmental Biology, Children's Hospital Research Foundation, Cincinnati, OH, USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Schilling
authors.forename: S L
authors.initials: SL
authors.lastname: Inman
authors.forename: L L
authors.initials: LL
authors.lastname: Morford
authors.forename: M S
authors.initials: MS
authors.lastname: Moran
authors.forename: C V
authors.initials: CV
authors.lastname: Vorhees
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D000927:Anticonvulsants / Q000009:adverse effects*; D001522:Behavior, Animal / Q000187:drug effects; D001724:Birth Weight / Q000187:drug effects; D001835:Body Weight / Q000187:drug effects; D004193:Discrimination Learning / Q000187:drug effects; D004192:Discrimination, Psychological / Q000187:drug effects; D005260:Female; D008098:Litter Size / Q000187:drug effects; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D008568:Memory / Q000187:drug effects; D010672:Phenytoin / Q000009:adverse effects*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects; D012193:Reversal Learning / Q000187:drug effects; D013037:Spatial Behavior / Q000187:drug effects*; D016019:Survival Analysis; D013550:Swimming; D014796:Visual Perception / Q000187:drug effects
chemical_list: D000927:Anticonvulsants; D010672:Phenytoin