Transient forebrain ischemia, produced by prolonged deprivation of blood flow to the brain, results in the insidious delayed degeneration of specific vulnerable neurons within the hippocampus.1,2) Among hippocampal neurons, pyramidal cells of the hippocampal CA1 region are most vulnerable to cerebral ischemia. 1,2) Death of the CA1 pyramidal cells following cerebral ischemia causes a variety of neurological dysfunction such as depression and memory deficits. 3,4) In traditional Eastern medicine, the extracts of various Berberidaceae (Berberis aquifolium, Berberis vulgaris and Berberis aristata) are used for rheumatic complaints and other types of chronic inflammation. 5,6) It has been reported that the functional components of the extracts were alkaloid components such as berberine, oxyacanthine, berbamine and palmatine.5) The anti-inflammatory and immunosuppressive activity of the Berberidaceae extract is well established. 7,8) Moreover, cardiotonic 9) and antiarrhythmic 10,11) activities have also been reported. Despite the considerable works done on berberic species in inflammation, cardiotonic and antiarrhythmic effects, its effects and roles in ischemic damage in the brain remains to be elucidated.It has been postulated that the neuronal hyperactivity due to an elevation of extracellular excitatory amino acids during ischemia leads to a massive increase in intracellular-free Ca 2ϩ , which may trigger the process of neuronal degeneration. [12][13][14] In the present study, therefore, we investigated the percentage of berberine by HPLC, which is active ingredient, and the neuroprotective effects of crude berberry extract (BE) against ischemic damage and the temporal and spatial alterations of N-methyl-D-aspartate receptor type 1 (NR1) and NR2A/B, the major excitatory amino acid receptors, immunoreactivities in the hippocampus induced by transient ischemia to examine anti-ischemic effects and their roles after transient forebrain ischemia in gerbils.
MATERIALS AND METHODS
Experimental Animals Male Mongolian gerbils (Meriones unguiculatus) obtained from the Experimental AnimalCenter, Hallym University, Chunchon, South Korea were used in this study. The animals were housed at constant temperature (23°C) at 60% relative humidity under a fixed 12 h light/dark cycle and had free access to food and water. Procedures involving animals and their care conformed with the our institution's guidelines, which are in compliance with current international laws and policies (NIH Guide for the Care and Use of Laboratory Animals, NIH Publication No. 85-23, 1985, revised 1996). All experiments were conducted to minimize the number of animals used and suffering caused.Plant Materials and Extraction Korean berberry (Berberis koreana) was collected in the area around Gyeonggi-do (South Korea) in September 2001. The plants were authenticated and the voucher specimen was deposited in the departmental herbarium of Kangwon National University. For the preparation of the ethanol extract of Berberis koreana, whole plants of theBerberis k...