Biomedical subjects

I Kohori

Publications and source records attributed to I Kohori.

3 recordsLinked to original sources

PubMed1992

[A simple method using a maze task for estimating working memory in mice].

Mice were housed in a cage with a T-maze for 7-9 h a day. A watering place was equipped at one end of the maze. At the other end of the maze, the right and left arms each have two exits, one of which leads to the home cage where food is placed, and the other of which leads to the watering place via a bypass. The exit leading to the home cage in either the right or left was alternately closed every two hours. One-way swinging doors were inserted at the entrance to each arm and between each bypass and the watering place. The mice housed in this apparatus acquired the alternation task at 5 s delay on the 6th day. As the delay became longer (5-150 s), correct response rate showed gradual decrease. Scopolamine (0.1-0.4 mg/kg) did not decrease correct response rate at 5 s delay, but did at longer delay (30 s and 60 s). These results suggest that this method is useful in estimating working memory of mice.

Animals↗

PubMed1991

The enhancement of the hypomotility induced by small doses of haloperidol in the phase of dopaminergic supersensitivity in mice.

Dopaminergic supersensitivity in mice was induced by pretreatment with a single injection of haloperidol (4.8 mg/kg). After the pretreatment, further treatment with haloperidol (0.6 or 0.01 mg/kg) was made at varying intervals, and catalepsy, locomotor activity and homovanillic acid (HVA) were measured. The intensity of the supersensitivity was evaluated by enhanced apomorphine (1 mg/kg)-induced climbing behavior. Supersensitivity was displayed on the 2nd and the 4th day. The cataleptogenic effect of haloperidol (0.6 mg/kg) was significantly weakened on the 1st, 2nd and 4th days. The motor inhibitory effect of haloperidol (0.01 mg/kg) increased on the 1st, 2nd and 4th days. Homovanillic acid was measured in the striatum and the prefrontal cortex on the 2nd day. Haloperidol (0.6 mg/kg) increased the concentrations of HVA in both regions of the brain. The increase in the concentrations of HVA in the striatum was blunted after the pretreatment, but such tolerance did not develop in the prefrontal cortex. Haloperidol (0.01 mg/kg) did not influence the concentration of HVA in both regions. These results suggest that the behavioral effect of a small dose of haloperidol may be enhanced, rather than reduced, in the phase of supersensitivity.

Animals↗

PubMed1987

Repeated low dose apomorphine induced subsensitivity of presynaptic dopamine receptors.

The influence of repeated administration of a low dose of apomorphine on presynaptic dopamine (DA) receptors was examined. (1) Male ddY mice were given a low dose of apomorphine (0.2 mg/kg) for 7 days. Following 2 drug-free days they were given apomorphine (0.2 mg/kg, IP), after which cage climbing behavior and the level of 3-methoxytyramine (3MT) in striatum was measured. Mice became tolerant to apomorphine's activity-depressing effect and 3MT-decreasing effect. (2) Mice were given haloperidol (1 mg/kg) for 7 days. Then after 2 drug-free days they were given 0.2 or 1.0 mg/kg of apomorphine, after which cage climbing behavior was measured. One mg/kg of apomorphine significantly increased cage climbing behavior, indicating that supersensitivity of postsynaptic DA receptors was induced by haloperidol, but the activity-depressing effect of 0.2 mg/kg of apomorphine was not modified. The results suggest that subsensitivity of presynaptic DA receptors participates in the tolerance to the activity-depressing effect of a low dose of apomorphine.

Animals↗