title: An animal model to detect learning deficits following treatment of the immature brain. Studies using radiation and methotrexate.
abstract: Learning deficits have been noted in children with acute leukemia given methotrexate (MTX) with and without cranial irradiation (RT) for prophylaxis. A rat model has been developed to assess treatment effects on learning. The test used was altered performance of a simultaneous discrimination task in a standard operant conditioning box, employing the mean number of days needed to score 80% correct responses as the criterion. An illustrative experiment distributed suckling rats among four groups: (1) 36 controls; (2) 14 cranial RT (1,000 R); (3) 14 MTX (5 mg/kg i.p.); (4) 36 RT + MTX 24 h later, and (5) 12 undernourished controls (to match poor weight gain patterns of treated animals). Survivors were tested 10-12 weeks later: values for groups 1-5 in order were 3.9, 4.1, 4.7, 5.0 and 4.0 days. Only group 4 results were significantly different from group 1 (p = less than 0.05).
mesh_terms: D000367:Age Factors; D000818:Animals; D001921:Brain / Q000528:radiation effects*; D003216:Conditioning, Operant / Q000187:drug effects / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D006801:Humans; D007859:Learning Disabilities / Q000139:chemically induced / Q000209:etiology*; D008727:Methotrexate / Q000009:adverse effects*; D011833:Radiation Injuries, Experimental / Q000209:etiology*; D011878:Radiotherapy / Q000009:adverse effects*; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D008727:Methotrexate