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Age-related changes in the peripheral nerves in the rats
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13-O 1 SYMPATHETIC
NERVOUS REGULATION OF RETINAL BLOOD FLOW IN AGED RATS. HARUMI HOTTA’, OSAMU INANAMI’, HIDEKI ITO’ AND AKTO SATO’, ‘Department of Autonomic Nervous Svstem, Tokvo Metronolitan Institute of Gerontolow. Tokvo 173. ‘Denartment of Endocrinoloev. Tokvo Metronolitan Geriatric HosDital, Tokvo 173. Japan Retinal blood flows (RBF) were compared in healthy adult (6-7 months old) and healthy aged (30-33 months old) Fischer-344 rats anesthetized with urethane. The RBF was measured either with hydrogen clearance method or using laser Doppler flowmetry. The RBF under the resting condition was markedly decreased in the aged rats to about 60% of the RBF in the adult rats. The resting RBF did not change significantly after severance of bilateral cervical sympathetic trunks (CSTs), indicating that the decrease in RBF in the aged rats was not related to higher activity of a sympathetic nerve. The electrical stimulation of a CST produced the frequencydependent decreases in RBF in the ipsilateral eye. The maximum decrease reached to 20-50% of the resting RBF in both adult and aged rats, indicating a well-maintained retinal vascular response to nerve in the aged rats.
,342
AGE-RELATED CHANGES IN THE PERIPHERAL NERVES IN THE RATS. KEN HASHIZUME AND KENRO KANDA, Deptartment of Kinesiology and Central Nervous System, Tokyo Metropolitan Institute of Gerontology, 35-2, Sakaecho, Itabashi-ku, Tokyo 173, Japan. Our previous studies demonstrated that the number of medial gastrocnemius (MG) motoneurons was significantly less in aged rats (26-27months old: F344, male) as compared with middle-aged rats (9-14months old), whereas no significant difference was found in that of forelimb, ulnar (U) motoneurons. In this paper, we examined the morphological changes of MG and U nerves in these animals. The MG and the U nerves were removed under pentobarbital anesthesia and fixed in 2.5% gultaraldehyde. They were later osmicated in 1% 0~04. Semithin cross sections were cut at 1 p m thickness from the specimen embedded in the Epon and stained with toluidine blue. In the MG nerves, the mean fascicular areas was significantly larger in aged rats. The mean number of myelinated fibers (including both afferent and efferent fibers) was significantly less in aged rats. This reduction was comparable to that for the number of MG motoneurons. The number of myelinated fibers was significantly correlated with that of their motoneurons. Axon diameters was also larger in aged rats, whereas myelin sheath thickness was not changed. In aged rats, the mean axon diameters was negatively correlated with the number of n -motoneurons. On the other hand, there was not a significant age-related reduction in the number of myelinated fibers in U nerves. Increased fascicular areas and axon diameters were also found in aged U nerves, but these changes were smaller compared with MG nerves. These results indicate that the morphological properties of myelinated fibers in the peripheral nerve well reflects degenerative changes of spinal motoneurons with increasing age. Although neuronal dropout is not apparent in U motoneurons to the age of 27 months, the age-related changes seem to progress in the peripheral portions.
13-03
AGE-RELATED CHANGES IN CORTICAL CATECHOLAMINERGIC AND SEROTONERGIC INNERVATIONS IN THE RAT. K..IWATA’. K..KITAJIMA2. Y..TSUBOI’. J..YAGI’, H..KAMOGAWA*. K..KANDA4. K.. HASHIZUMEJ. N..OKADOS AND R..SUMINOl. Dents. Phvsioll and Pathonhvsiol2.. Sch. Dent.. Nihon Univ.. Kanda Surueadai Chivoda-ku Tokvo 101 Jauan. Deots. Kinesiol.3 and Cez nervous svstem4. Tokvo Metronolitan Institute of Gerontoloev 35-2. Sakaecho. Itabashi-ku. Tokvo 173 Janan. Deot. Anat.. Inst. Basic Med. Sci.. Univ. Tsukubas. Tsukubashi. Ibaraki 305 Jaoan Noradrenergic and serotonergic terminal distributions in the cerebral cortex of the old (31 months) and young (3 months) rats were studied with immunohistochemical techniques. The animals were anesthetized with sodium pentobarbital (50 mg/kg, i.p.) and perfused with 4% paraformaldehyde in PB. Sections from frontal (Fr), somatosensory (So), occipital (Oc) and visual (Vi) cortices were processed with ABC immunohistochemistry that employed polyclonal antisera to dopamine fl-hydroxylase (rabbit anti DBH) and to serotonine (rabbit anti 5-HT). Distribution of 5-HT like immunoreactive (5-HT LI) and DBH like immunoreactive (DBH LI) terminals was dense in superficial (I-II) and sparse in deeper (III,IV,V and VI) laminae. The number of 5-HT LI fibers and terminals was decreased in the superficial laminae of Fr, So and Oc cortices, which was less extent in Vi cortex of the old rats. In the deeper laminae alteration of density of 5-HT LI fibers and terminals was not found. On the other hand, DBH LI fibers and terminals were slightly decreased in the superficial laminae of Fr, So and Oc cortices, but not in the deeper laminae. However, the number of them in Vi cortex was decreased in both superficial and deep laminae of the old rats. These findings suggest that serotonergic fibers and terminals in the superficial laminae (Fr, Oc and So cortices) and those of noradrenergic ones (Vi cortex) would be mainly involved in degeneration process of the cerebral cortex.
13-O 1 SYMPATHETIC
NERVOUS REGULATION OF RETINAL BLOOD FLOW IN AGED RATS. HARUMI HOTTA’, OSAMU INANAMI’, HIDEKI ITO’ AND AKTO SATO’, ‘Department of Autonomic Nervous Svstem, Tokvo Metronolitan Institute of Gerontolow. Tokvo 173. ‘Denartment of Endocrinoloev. Tokvo Metronolitan Geriatric HosDital, Tokvo 173. Japan Retinal blood flows (RBF) were compared in healthy adult (6-7 months old) and healthy aged (30-33 months old) Fischer-344 rats anesthetized with urethane. The RBF was measured either with hydrogen clearance method or using laser Doppler flowmetry. The RBF under the resting condition was markedly decreased in the aged rats to about 60% of the RBF in the adult rats. The resting RBF did not change significantly after severance of bilateral cervical sympathetic trunks (CSTs), indicating that the decrease in RBF in the aged rats was not related to higher activity of a sympathetic nerve. The electrical stimulation of a CST produced the frequencydependent decreases in RBF in the ipsilateral eye. The maximum decrease reached to 20-50% of the resting RBF in both adult and aged rats, indicating a well-maintained retinal vascular response to nerve in the aged rats.
,342
AGE-RELATED CHANGES IN THE PERIPHERAL NERVES IN THE RATS. KEN HASHIZUME AND KENRO KANDA, Deptartment of Kinesiology and Central Nervous System, Tokyo Metropolitan Institute of Gerontology, 35-2, Sakaecho, Itabashi-ku, Tokyo 173, Japan. Our previous studies demonstrated that the number of medial gastrocnemius (MG) motoneurons was significantly less in aged rats (26-27months old: F344, male) as compared with middle-aged rats (9-14months old), whereas no significant difference was found in that of forelimb, ulnar (U) motoneurons. In this paper, we examined the morphological changes of MG and U nerves in these animals. The MG and the U nerves were removed under pentobarbital anesthesia and fixed in 2.5% gultaraldehyde. They were later osmicated in 1% 0~04. Semithin cross sections were cut at 1 p m thickness from the specimen embedded in the Epon and stained with toluidine blue. In the MG nerves, the mean fascicular areas was significantly larger in aged rats. The mean number of myelinated fibers (including both afferent and efferent fibers) was significantly less in aged rats. This reduction was comparable to that for the number of MG motoneurons. The number of myelinated fibers was significantly correlated with that of their motoneurons. Axon diameters was also larger in aged rats, whereas myelin sheath thickness was not changed. In aged rats, the mean axon diameters was negatively correlated with the number of n -motoneurons. On the other hand, there was not a significant age-related reduction in the number of myelinated fibers in U nerves. Increased fascicular areas and axon diameters were also found in aged U nerves, but these changes were smaller compared with MG nerves. These results indicate that the morphological properties of myelinated fibers in the peripheral nerve well reflects degenerative changes of spinal motoneurons with increasing age. Although neuronal dropout is not apparent in U motoneurons to the age of 27 months, the age-related changes seem to progress in the peripheral portions.
13-03
AGE-RELATED CHANGES IN CORTICAL CATECHOLAMINERGIC AND SEROTONERGIC INNERVATIONS IN THE RAT. K..IWATA’. K..KITAJIMA2. Y..TSUBOI’. J..YAGI’, H..KAMOGAWA*. K..KANDA4. K.. HASHIZUMEJ. N..OKADOS AND R..SUMINOl. Dents. Phvsioll and Pathonhvsiol2.. Sch. Dent.. Nihon Univ.. Kanda Surueadai Chivoda-ku Tokvo 101 Jauan. Deots. Kinesiol.3 and Cez nervous svstem4. Tokvo Metronolitan Institute of Gerontoloev 35-2. Sakaecho. Itabashi-ku. Tokvo 173 Janan. Deot. Anat.. Inst. Basic Med. Sci.. Univ. Tsukubas. Tsukubashi. Ibaraki 305 Jaoan Noradrenergic and serotonergic terminal distributions in the cerebral cortex of the old (31 months) and young (3 months) rats were studied with immunohistochemical techniques. The animals were anesthetized with sodium pentobarbital (50 mg/kg, i.p.) and perfused with 4% paraformaldehyde in PB. Sections from frontal (Fr), somatosensory (So), occipital (Oc) and visual (Vi) cortices were processed with ABC immunohistochemistry that employed polyclonal antisera to dopamine fl-hydroxylase (rabbit anti DBH) and to serotonine (rabbit anti 5-HT). Distribution of 5-HT like immunoreactive (5-HT LI) and DBH like immunoreactive (DBH LI) terminals was dense in superficial (I-II) and sparse in deeper (III,IV,V and VI) laminae. The number of 5-HT LI fibers and terminals was decreased in the superficial laminae of Fr, So and Oc cortices, which was less extent in Vi cortex of the old rats. In the deeper laminae alteration of density of 5-HT LI fibers and terminals was not found. On the other hand, DBH LI fibers and terminals were slightly decreased in the superficial laminae of Fr, So and Oc cortices, but not in the deeper laminae. However, the number of them in Vi cortex was decreased in both superficial and deep laminae of the old rats. These findings suggest that serotonergic fibers and terminals in the superficial laminae (Fr, Oc and So cortices) and those of noradrenergic ones (Vi cortex) would be mainly involved in degeneration process of the cerebral cortex.