Changes of the Cholinergic Innervation to the Hippocampus after Entorhinal Cortex Lesion in Rat / 대한해부학회지

The hippocampus is known as involved in learning and memory functions and the entorhinal cortex plays a crucial role as a gateway connecting the several areas and hippocampal formation. Entorhinal cortex lesions have been employed in numerous studies as the Alzheimer's disease model. The purpose of this study were to identify the CNS hip-pocampal and cholinergic pathway and to investigate the morphological changes of the hippocampal cholinergic inner-vations by using the Pseudorabies virus injection into the hippocampus after entorhinal cortex lesions. The pseudorabies virus and double labelled neurons (ChAT and PRV) were distributed at several different nuclei including agranular insular cortex, bed nucleus of stria terminalis, central amygdala, globus pallidus, lateral segment, lateral hypothalamic area, laterodorsal tegmental nucleus, medial septal nucleus, mesencephalic reticular nucleus, periaqueductal gray matter and substantia innominata The morphological changes were observed in the hippocampal cholinergic innervation after entorhinal cortex lesions. These data suggested that the hippocampal cholinergic innervation showed morphological changes throughout the whole brain areas after entorhinal cortex lesion.

Effect of Panax ginseng on latency of passive avoidance response and neuronal damage of hippocampus

The effects of crude saponin (SAP) and alkaloid (ALK) fractions of Panax ginseng C.A. Meyer on the detrimental effects of electroconvulsive shock (ECS) and scopolamine on passive avoidance response (PAR) were studied in male Sprague-Dawley rats, referring their effects on the neuronal injury and plasticity of hippocampus in response to electrolytic lesion of left entorhinal cortex (ECL). The detrimental ECS effect on PAR was attenuated by pre- and post-treatments with SAP and ALK, respectively, or by pretreatment with aminoguanidine (AG), an inhibitor of diamine oxidase and NO synthase. And the detrimental scopolamine effect on PAR was also inhibited by pretreatment with ALK or AG, and by posttreatment with SAP or ALK, respectively. On the 7th day after ECL, the brain sections stained by cresyl violet and by acetylcholinesterase (AChE) histochemistry, respectively, showed the chromatolysis and numeral decrease of neurons and the reduction of AChE reactivity in the hippocampus CA1 area and to a lesser extent, in the dentate gyrus. The neuronal cell death of the CA1 area was significantly reduced by SAP, ALK, or AG, and the reduction of AChE reactivity was significantly attenuated by SAP or ALK and to a lesser extent by AG. These results suggests that the protective effect of ginseng SAP and ALK fractions on ECS- or scopolamine-induced impairment of PAR may be ascribed in part to preservation of hippocampal neurons, particularly cholinergic neurons.