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The effect of dopamine cell transplantation on the circling behavior of the rat with lesion of the nigrostriatal dopaminergic pathway
$11 THE INFLUENCE OF OSMORECEPTOR MECHANISMS IN THE HEPATOPORTAL REGION AND THE AREA POSTREMA ON SALT APPETITE
AKIRA ADACHI, TOKO SURUGA and MOTOI KOBASHI, Department of Physiology, Okayama University 2-5-1 S h i k a t a - c h o , O k a y a m a 700, J a p a n .
Dental
School,
Rejection thresholds for saltiness and bitterness were determined on hepatic vagotomized rats as well as area postrema lesioned rats, using the improved method that has been previously reported ( N e u r o s c i . L e t t . 13, $ 1 2 6 ) . It was revealed that both destructions caused an selective increase in rejection thresholds for saltiness. This evidence suggests that the osmoreceptor mechanism might exist in the area postrema (AP) as well as in the hepatoportal region, w h i c h in t u r n exerts an influence on salt appetite. Therefore, electrophysiological examinations were designed to find out sodium (osmo-) responsive neurons within the AP and the solitary tract nucleus(NTS). Iontophoretic microinjection of sodium ions elicited a marked response on neurons within the AP, a s w e l l a s the NTS neurons which were affected by osmotic afferent invasion from the hepatoportal region. It is speculated that these osmoresponsive neural activities might suppress salt appetite to control excess uptake of sodium chloride.
THE EFFECT OF DOPAMINE CELL TRANSPLANTATION ON THE CIRCLING BEHAVIOR OF THE RAT WITH LESION OF THE NIGROSTRIATAL DOPAMINERGIC PATHWAY HITOO NISHINO, TAKETOSHI ONO and JIRO TAKAHASHI, Department of Physiology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Sugitani, Toyama 930-01, Japan The effects of transplanting dopamine cell-suspensions into the caudate nucleus of rats with unilateral nigrostriatal dopaminergic pathway lesions were studied, and the results of transplantation variables were investigated. Unilateral microinjection of 6-OHDA into the nigrostriatal dopaminergic pathway induced circling behavior to the contralateral side, because of the stimulating effect of the drug. This effect disappeared within one or two days, and thereafter no apparent spontaneous behavioral deficit was observed. Systemic injection of Met-amphetamine (3-5mg/kg, i.p.) induced circling behavior to the lesioned side, and this motor imbalance remained after the lesion. In these animals, caudate dopamine content in the lesioned side decreased to less than 10% of normal, but the decrease of DOPAC content was slight. The enhanced DOPAC/DA ratio suggests a high turnover rate in the dopamine system. Microinjection (transplantation) of fetal midbrain dopamine cell-suspensions into the caudate nucleus of the animal, improved the behavioral imbalance. This effect appeared slightly in the second week after transplantation, definitely in the third, and completely in the fourth week. The results of the behavioral improvement confirmed that the important factors in condition variables of the transplantation are, i) age of the fetus (13-15 days), 2) volume of injection (multiple injections, total volume less than i0 ~i) and 3) number (107-108 cells/ml) and viability (more than 90%) of the cells in the suspensions.
AKIRA ADACHI, TOKO SURUGA and MOTOI KOBASHI, Department of Physiology, Okayama University 2-5-1 S h i k a t a - c h o , O k a y a m a 700, J a p a n .
Dental
School,
Rejection thresholds for saltiness and bitterness were determined on hepatic vagotomized rats as well as area postrema lesioned rats, using the improved method that has been previously reported ( N e u r o s c i . L e t t . 13, $ 1 2 6 ) . It was revealed that both destructions caused an selective increase in rejection thresholds for saltiness. This evidence suggests that the osmoreceptor mechanism might exist in the area postrema (AP) as well as in the hepatoportal region, w h i c h in t u r n exerts an influence on salt appetite. Therefore, electrophysiological examinations were designed to find out sodium (osmo-) responsive neurons within the AP and the solitary tract nucleus(NTS). Iontophoretic microinjection of sodium ions elicited a marked response on neurons within the AP, a s w e l l a s the NTS neurons which were affected by osmotic afferent invasion from the hepatoportal region. It is speculated that these osmoresponsive neural activities might suppress salt appetite to control excess uptake of sodium chloride.
THE EFFECT OF DOPAMINE CELL TRANSPLANTATION ON THE CIRCLING BEHAVIOR OF THE RAT WITH LESION OF THE NIGROSTRIATAL DOPAMINERGIC PATHWAY HITOO NISHINO, TAKETOSHI ONO and JIRO TAKAHASHI, Department of Physiology, Faculty of Medicine, Toyama Medical and Pharmaceutical University, Sugitani, Toyama 930-01, Japan The effects of transplanting dopamine cell-suspensions into the caudate nucleus of rats with unilateral nigrostriatal dopaminergic pathway lesions were studied, and the results of transplantation variables were investigated. Unilateral microinjection of 6-OHDA into the nigrostriatal dopaminergic pathway induced circling behavior to the contralateral side, because of the stimulating effect of the drug. This effect disappeared within one or two days, and thereafter no apparent spontaneous behavioral deficit was observed. Systemic injection of Met-amphetamine (3-5mg/kg, i.p.) induced circling behavior to the lesioned side, and this motor imbalance remained after the lesion. In these animals, caudate dopamine content in the lesioned side decreased to less than 10% of normal, but the decrease of DOPAC content was slight. The enhanced DOPAC/DA ratio suggests a high turnover rate in the dopamine system. Microinjection (transplantation) of fetal midbrain dopamine cell-suspensions into the caudate nucleus of the animal, improved the behavioral imbalance. This effect appeared slightly in the second week after transplantation, definitely in the third, and completely in the fourth week. The results of the behavioral improvement confirmed that the important factors in condition variables of the transplantation are, i) age of the fetus (13-15 days), 2) volume of injection (multiple injections, total volume less than i0 ~i) and 3) number (107-108 cells/ml) and viability (more than 90%) of the cells in the suspensions.