Biomedical subjects

J W Ni

Publications and source records attributed to J W Ni.

5 recordsLinked to original sources

PubMed1996

Permanent occlusion of bilateral internal carotid arteries produces cognitive deficits in two learning behavior tasks.

We investigated the effects of permanent bilateral occlusion of the internal carotid arteries (2ICAO) on the learning and memory performances in rats to evaluate the permanent 2ICAO rats as a model for vascular dementia. The learning and memory performance was tested by a step-through passive avoidance task and an 8-arm radial maze task. Permanent 2ICAO decreased cerebral blood flows in the cortex and hippocampus by 46.3 +/- 3.3 and 21.1 +/- 4.6%, respectively, when measured at 15 min after occlusion. In the passive avoidance task, the 2ICAO rats showed no impairment of learning or of memory retention when tested 1 h after learning trial, while they showed a shorter latency than sham-operated rats when tested 24 h after learning trial. In the radial maze learning task, the non-pretrained 2ICAO rats showed impairment. The pretrained 2ICAO rats had no deficit in the radial maze retention task but they showed impaired performance when a 3-min delay was interposed in the task. These results suggest that permanent 2ICAO is a useful animal model for studying vascular dementia.

Animals↗

PubMed1995

Neuronal damage and decrease of central acetylcholine level following permanent occlusion of bilateral common carotid arteries in rat.

The neuronal damages and the changes in central acetylcholine (ACh) and choline (Ch) contents following permanent occlusion of bilateral common carotid arteries (2VO) of rats were investigated 1 and 4 months after the operation. Two types of neuronal damages were observed in the rats with permanent 2VO. The first type was the infarctions observed in the cerebral cortex and striatum. The infarction in the cortex and striatum was observed in 28.6 and 42.9% of the animals examined 1 month after permanent 2VO, respectively. These ratios did not change even when examined 4 months after permanent 2VO, suggesting that this type of neuronal damage is due to acute ischemic attacks. The second type was progressive neuronal damages observed in the hippocampus and white matter: the neuronal loss in the CA1 subfield appeared 4 months but not 1 month after permanent 2VO and the rarefaction of white matter which was observed 1 months after permanent 2VO and markedly increased 4 months after the operation. Moreover, ACh level significantly decreased in the striatum but not in the cortex, hippocampus or hypothalamus 1 month after permanent 2VO, while the ACh levels in the cortex, striatum and hypothalamus, and Ch levels in all the regions tested significantly decreased when tested 4 months after the operation. These changes did not accompany necrosis. These results suggest that the progressive neuronal degeneration and cholinergic dysfunction following the permanent 2VO are in part involved in chronic cerebral hypoperfusion-induced long-lasting cognition deficits in rats.

Acetylcholine↗

PubMed1995

Tetramethylpyrazine improves spatial cognitive impairment induced by permanent occlusion of bilateral common carotid arteries or scopolamine in rats.

Effects of tetramethylpyrazine (TMP), a major constituent of Ligusticum chuanxiong, on spatial cognitive impairment induced by permanent occlusion of bilateral common carotid arteries (2VO) and scopolamine were investigated using 8-arm radial maze performance in rats. Permanent 2VO produced a severe learning deficit in non-pretrained rats. Daily administration of TMP (3-10 mg/kg, i.p.) from the 3rd day after permanent 2VO significantly improved the learning deficit. TMP did not influence the impairment of the retention task in the pretrained permanent 2VO rats, but it tended to reduce the number of errors elevated by 3-min delay interposition in these rats. In the scopolamine model, scopolamine (0.3 mg/kg, i.p.) significantly decreased the initial correct response and increased the number of errors. Single administration of TMP (1-3 mg/kg, i.p.) dose-dependently reversed the scopolamine-induced impairment of the maze performance. These results suggest that TMP has therapeutic potential for the treatment of dementia caused by cholinergic dysfunction and/or decrease of cerebral blood flow.

Animals↗

PubMed1993

Peony and its major constituent, paeoniflorin, improve radial maze performance impaired by scopolamine in rats.

A traditional Chinese medicine, Shimotsu-to has been shown to improve spatial working memory in rats. Shimotsu-to consists of four herbs, Japanese angelica root, cnidium rhizome, peony root, and rehmannia root. In the present study, the effects of aqueous extracts of each component herb on scopolamine (0.3 mg/kg)-induced spatial working memory disruption were examined using an eight-arm radical maze task in rats. Among the four component herbs, peony root extract (0.25 and 1 g dried herb/kg, PO) exhibited the most potent antagonizing effect on the scopolamine disruption of the choice accuracy. Japanese angelica root extract (1 g dried herb/kg, PO) also significantly attenuated the scopolamine disruption, whereas neither cnidium rhizome nor rehmannia root affected it. Paeoniflorin (0.01-1 mg/kg, PO), a major constituent of peony root, dose-dependently attenuated the scopolamine-induced impairment in the choice accuracy. Scopolamine (0.3 mg/kg, IP) significantly decreased the acetylcholine contents in the hippocampus, cortex, and striatum. Although paeoniflorin alone did not affect the acetylcholine contents, pretreatment with paeoniflorin significantly prevented the scopolamine-induced decrease in the acetylcholine content in the striatum, but not in the hippocampus or cortex. These data suggest that peony root mainly contributes to the cognitive enhancing effect of Shimotsu-to and that paeoniflorin may be one of the active constituents of peony root.

Acetylcholine↗

PubMed1991

A kampo prescription, shimotsu-to, improves scopolamine-induced spatial cognitive deficits in rats.

The effect of a Kampo (traditional Chinese medicine) prescription, Shimotsu-to, on spatial cognitive deficits produced by scopolamine was examined using an eight-arm radial maze and a T-maze. Scopolamine (SCOP; 0.075-0.3 mg/kg, ip) dose-dependently disrupted the radial maze performance. Single doses of Shimotsu-to (0.5 and 1.0 g/kg, po) as well as physostigmine (0.15 and 0.3 mg/kg, ip) improved the SCOP (0.3 mg/kg)-induced performance deficits in a dose-dependent manner. Shimotsu-to administered for 1 week in drinking water (0.5 and 1.0 g/kg/day) also exhibited dose-dependent reversal of SCOP-induced impairments in the radial maze performance. The same treatment improved SCOP (0.2 mg/kg)-induced impairments in T-maze delayed alternation performance. These data clearly demonstrated the beneficial effects of Shimotsu-to on spatial cognition.

Administration, Oral↗