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1507 Role of serotonin on postnatal development of locomotor activities in rat
S157 "1506
AN IN VITRO STUDY OF T H E CENTRAL PATTERN G E N E R A T O R FOR FORELIMB L O C O M O T I O N IN T H E N E W B O R N RAT. YUMI W A T A N A B E , M A K I T O I I Z U K A A N D N O R I O KUDO, Dept. of Physiol., Inst. o f Basic Med. Sci., Univ. of Tsukuba, Tsukuba, lbaraki 305, Japan.. Properties of the central pattern generator (CPG) for forelimb locomotion and effects from the CPG for hindlimb locomotion were studied using isolated spinal cord or brain stem-spinal cord preparations from newborn rats (P0-3). Bath application of N-methyl-D-aspartate (NMDA; 5-10/.tM) induced alternating rhythmic activity (0.5-1Hz) in the C8-Thl ventral roots on the left and right sides in an isolated cervicothoracic spinal cord preparation, suggesting that the CPG for forelimb locomotion located in the cervical-upper thoracic spinal cord. To examine the interaction between the cervical and the lumbar CPG, the experimental chamber was partitioned at ihe mid-thoracic level and perfused by separate solutions in a brain stem-spinal cord preparation. Repetitive electrical stimulation of the brain stem evoked the locomotor rhythm in cervical and lumbar ventral roots. The rhythm in the lumbar ventral root was not interrupted by the removal of Ca ions from the solution partially perfused to the brain stem-cervical spinal cord. In contrast, the brain stem-induced rhythm in the cervical ventral root disappeared after the removal of Ca ions from the lumbar.spinal cord. Furthermore, partial application of NMDA to the lumbar spinal cord induced locomotor rhythm not only in the lumbar ventral root but also the cervical ventral root. These results indicate that the cervical CPG would be activated by ascending inflows from the lumbar CPG.
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ROLE OF SEROTONIN ON POSTNATAL DEVELOPMENT OF LOCOMOTORACTIVITIES IN RAT. HIDEAKI MYOGA1. HIROMASA I W A K I R I 2 , ~ T t ~ I . Y O S H I F U M I KOI3AYASHI1. SHIGEMI blORI2, 1Deot. of Physiol.. Asahikawa Medical Colleee. Asahikawa. 078. Janan and 2Lab. of Neurobiol.. Natl. Inst. for Physiol. Sci.~ Mvodai]i. Okazaki'.444 ,Japan
The role of serotonin (5-HT) on postnatal development of locomotor activities and postural reflexes was studied in Sprague-Dawley rats from postnatal days (PND) 1 to 14. Six groups of litters, each consisting of 8 pups, were employed in this study. Four groups of litters (n=32) were used as a control group, and two groups of litters (n=16) were given pchlorophenylalanine (PCPA), an inhibitor of 5-HT synthesis. PCPA(200mg/kg) ,.,,'as intraperitoneally administered once every 3 days starting at PND 1. Spontaneous locomotor activities were measured by attaching a fiat resonance coil (diameters from 15 to 23mm) to the abdomen of each rat. It walked freely with the coil on the surface of horizontally placed digitizer (31 x 46cm). X,Y-coordinates of the rat on the digitizer was detected automatically from the position of the resonance coil, and the data were fed into the microcomputer for later analyses. Postnatal development of the PCPA-treated rats, as measured from the body weight, was impaired starting at PND 6 in comparison to that of the control rats. At PND 14, the body weight of the control rats was 29.7-,-2.3g (n=30), while that of the PCPA-treated rats was 24.0-3.8g (n=13). In control rats, voluntary locomotor distance per 20 rain, which ,,','as measured during dark period, increased slowly from PND 1 to 5, and then rapidly to PND 14. In the PCPA-treated rats, locomotor distance was significantly decreased along with poor development of postural reflexes at each PND. Total locomotor distance per 20 min in control rats was 404-266cm (n= 19) at PND 6 and 4415±1364cm (n=13) at PND 13, while in PCPA-treated rats, it was 217-.*61cm (n=10) at PND 6 and 2812-1047cm (n=10) at PND 13.
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COMPARISON OF THE EXECUTING NEURONAL MECHANISMS RELATED TO THE PONTINE CARBACHOL-INDUCED AND ELECTRICALLY-INDUCED GENERALIZED SUPPRESSION OF POSTURAL MUSCLE TONE. ~ 1 ~ 2 . HIROMASA IWAKIRI1. YOSHIYUMI KOBAYASHI2, KIYOJI MAT~UYAMA 2 AND KAORU TAKAKUSAKI2, 1Lab. of Neurobiol_ Natl. Inst. for Physiol. Sci.. Myodaiii. Okazaki. 444, Japan and 2Dent. of Physiol.. Asahikawa Medical College. Asahikawa. 078. Japan Focal microinjection of cholinergic agonists into the pontine reticular formation (PRF) results in generalized suppression of postural muscle tone in both acute decerebrate and intact, awake cats. In an acute decerebrate cat, we have recently found that microstimulation of the dorsomedial portion of the PRF results in generalized suppression of tonic activities in the neck, forelimb, lumbar back and hindlimb muscles, bilaterally. In this study, attempts were made to elucidate the executing pontomedullary and spinal neuronal mechanisms related to the generation of postural suppression. Using the anterograde neural tracer (PHA-L), both the reticuloreticular and reticulospinal projections were identified, both of them originating from the pontine stimulus sites. Reticuloreticular projections were to the b~ateral medullary reticular formation with an ipsilateral dominance. Single reticulospinal fibers gave offa few axon collaterals at each segment of the cervical and thoracic cord as they decended caudally. These axon collaterals innervated small-sized neurons in Rexed's laminae V, VI and VII. With this, the diameter of the axon collaterals became thinner. Based on the fine architecture of the reticuloreticular and reticulospinal projections, and on the characteristic responses of pontomedullary and spinal intemeurons, the similarity and difference in the pontomedullary and spinal mechanisms related to the chemically and electrically-induced posturaI atonia will be-discussed in relation to the neuronal mechanisms of REM-sleep atonia.
AN IN VITRO STUDY OF T H E CENTRAL PATTERN G E N E R A T O R FOR FORELIMB L O C O M O T I O N IN T H E N E W B O R N RAT. YUMI W A T A N A B E , M A K I T O I I Z U K A A N D N O R I O KUDO, Dept. of Physiol., Inst. o f Basic Med. Sci., Univ. of Tsukuba, Tsukuba, lbaraki 305, Japan.. Properties of the central pattern generator (CPG) for forelimb locomotion and effects from the CPG for hindlimb locomotion were studied using isolated spinal cord or brain stem-spinal cord preparations from newborn rats (P0-3). Bath application of N-methyl-D-aspartate (NMDA; 5-10/.tM) induced alternating rhythmic activity (0.5-1Hz) in the C8-Thl ventral roots on the left and right sides in an isolated cervicothoracic spinal cord preparation, suggesting that the CPG for forelimb locomotion located in the cervical-upper thoracic spinal cord. To examine the interaction between the cervical and the lumbar CPG, the experimental chamber was partitioned at ihe mid-thoracic level and perfused by separate solutions in a brain stem-spinal cord preparation. Repetitive electrical stimulation of the brain stem evoked the locomotor rhythm in cervical and lumbar ventral roots. The rhythm in the lumbar ventral root was not interrupted by the removal of Ca ions from the solution partially perfused to the brain stem-cervical spinal cord. In contrast, the brain stem-induced rhythm in the cervical ventral root disappeared after the removal of Ca ions from the lumbar.spinal cord. Furthermore, partial application of NMDA to the lumbar spinal cord induced locomotor rhythm not only in the lumbar ventral root but also the cervical ventral root. These results indicate that the cervical CPG would be activated by ascending inflows from the lumbar CPG.
"15 0 7
ROLE OF SEROTONIN ON POSTNATAL DEVELOPMENT OF LOCOMOTORACTIVITIES IN RAT. HIDEAKI MYOGA1. HIROMASA I W A K I R I 2 , ~ T t ~ I . Y O S H I F U M I KOI3AYASHI1. SHIGEMI blORI2, 1Deot. of Physiol.. Asahikawa Medical Colleee. Asahikawa. 078. Janan and 2Lab. of Neurobiol.. Natl. Inst. for Physiol. Sci.~ Mvodai]i. Okazaki'.444 ,Japan
The role of serotonin (5-HT) on postnatal development of locomotor activities and postural reflexes was studied in Sprague-Dawley rats from postnatal days (PND) 1 to 14. Six groups of litters, each consisting of 8 pups, were employed in this study. Four groups of litters (n=32) were used as a control group, and two groups of litters (n=16) were given pchlorophenylalanine (PCPA), an inhibitor of 5-HT synthesis. PCPA(200mg/kg) ,.,,'as intraperitoneally administered once every 3 days starting at PND 1. Spontaneous locomotor activities were measured by attaching a fiat resonance coil (diameters from 15 to 23mm) to the abdomen of each rat. It walked freely with the coil on the surface of horizontally placed digitizer (31 x 46cm). X,Y-coordinates of the rat on the digitizer was detected automatically from the position of the resonance coil, and the data were fed into the microcomputer for later analyses. Postnatal development of the PCPA-treated rats, as measured from the body weight, was impaired starting at PND 6 in comparison to that of the control rats. At PND 14, the body weight of the control rats was 29.7-,-2.3g (n=30), while that of the PCPA-treated rats was 24.0-3.8g (n=13). In control rats, voluntary locomotor distance per 20 rain, which ,,','as measured during dark period, increased slowly from PND 1 to 5, and then rapidly to PND 14. In the PCPA-treated rats, locomotor distance was significantly decreased along with poor development of postural reflexes at each PND. Total locomotor distance per 20 min in control rats was 404-266cm (n= 19) at PND 6 and 4415±1364cm (n=13) at PND 13, while in PCPA-treated rats, it was 217-.*61cm (n=10) at PND 6 and 2812-1047cm (n=10) at PND 13.
"15 0 8
COMPARISON OF THE EXECUTING NEURONAL MECHANISMS RELATED TO THE PONTINE CARBACHOL-INDUCED AND ELECTRICALLY-INDUCED GENERALIZED SUPPRESSION OF POSTURAL MUSCLE TONE. ~ 1 ~ 2 . HIROMASA IWAKIRI1. YOSHIYUMI KOBAYASHI2, KIYOJI MAT~UYAMA 2 AND KAORU TAKAKUSAKI2, 1Lab. of Neurobiol_ Natl. Inst. for Physiol. Sci.. Myodaiii. Okazaki. 444, Japan and 2Dent. of Physiol.. Asahikawa Medical College. Asahikawa. 078. Japan Focal microinjection of cholinergic agonists into the pontine reticular formation (PRF) results in generalized suppression of postural muscle tone in both acute decerebrate and intact, awake cats. In an acute decerebrate cat, we have recently found that microstimulation of the dorsomedial portion of the PRF results in generalized suppression of tonic activities in the neck, forelimb, lumbar back and hindlimb muscles, bilaterally. In this study, attempts were made to elucidate the executing pontomedullary and spinal neuronal mechanisms related to the generation of postural suppression. Using the anterograde neural tracer (PHA-L), both the reticuloreticular and reticulospinal projections were identified, both of them originating from the pontine stimulus sites. Reticuloreticular projections were to the b~ateral medullary reticular formation with an ipsilateral dominance. Single reticulospinal fibers gave offa few axon collaterals at each segment of the cervical and thoracic cord as they decended caudally. These axon collaterals innervated small-sized neurons in Rexed's laminae V, VI and VII. With this, the diameter of the axon collaterals became thinner. Based on the fine architecture of the reticuloreticular and reticulospinal projections, and on the characteristic responses of pontomedullary and spinal intemeurons, the similarity and difference in the pontomedullary and spinal mechanisms related to the chemically and electrically-induced posturaI atonia will be-discussed in relation to the neuronal mechanisms of REM-sleep atonia.