title: [Effects of thyroid hormone on cognitive function in rats with chronic cerebral ischemia].
abstract: OBJECTIVE
  To study the characteristics of cognitive dysfunction in rats with chronic cerebral ischemia and the effects of thyroid hormone on the rats' cognitive function.
  
  
  METHODS
  Thirty-one male SD rats were randomly allocated into normal control group (n=12), operation group (with bilateral carotid artery ligation and examined 5 weeks later, n=6), acute phase treatment group (APT, with bilateral carotid artery ligation and intragastric administration of thyroid hormone at 20 mg once daily for 5 weeks starting from the day of operation, n=7) and chronic phase treatment group (CPT, with the operation and thyroid hormone administration in an identical manner started from the sixth week following the operation, n=6). Morris water maze test was performed at the end of experiment. One-way ANOVA was used to estimate the differences in the learning and memory functions of the rats using SPSS10.0 for Windows.
  
  
  RESULTS
  The average latent period of the operation group was significantly prolonged in comparison with that of the other groups (P<0.05) in spatial orientation test. The probe time (time spent in the quadrant where the platform was once situated) of normal control was much shorter than those of the operation, APT and CPT groups in spatial probe test (P<0.05), and the operation group had the poorest score. The average latent period of the operation and CPT was longer than that of the other groups (P<0.05) in working-memory task (P<0.05), and the operation group again had the poorest score.
  
  
  CONCLUSIONS
  Spatial cognitive function is totally damaged in rats with chronic cerebral ischemia, and learning can not induce the formation long-term memory because of short-term memory damage. Thyroid hormone may lessen but can not fully repair the damage of the cognitive dysfunction resulting from chronic cerebral ischemia, and early intervention with thyroid hormone may be beneficial for chronic cerebral ischemia.
authors.affiliation: Department of Neurology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China. zhpn@fimmu.com
authors.forename: Qun
authors.initials: Q
authors.lastname: Wang
authors.forename: Yong-jun
authors.initials: YJ
authors.lastname: Li
authors.forename: Bing-xun
authors.initials: BX
authors.lastname: Lu
mesh_terms: D000818:Animals; D002545:Brain Ischemia / Q000188:drug therapy*; D002908:Chronic Disease; D003071:Cognition / Q000187:drug effects*; D003072:Cognition Disorders / Q000188:drug therapy* / Q000209:etiology; D008297:Male; D018782:Maze Learning / Q000187:drug effects; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013963:Thyroid Hormones / Q000627:therapeutic use*
chemical_list: D013963:Thyroid Hormones