phenylephrine-hydrochloride and Nerve-Degeneration

Topics: Animals; Anura; Denervation; Dogs; Electrophysiology; Epithelium; Inflammation; Nerve Degeneration; Nerve Regeneration; Neurons; Neurosurgery; Nose; Olfactory Nerve; Rabbits; Rats; Sulfates; Zinc

Adult vertebrate olfactory epithelia are unique in their continual sensory neuron turnover and replacement. This paper describes studies of various aspects of the death of these receptor neurons in unoperated rats and at 12 days and 7 weeks after unilateral ablation of the olfactory bulb, the receptor neuron synaptic target. Particular attention has been focused on the lifespan of the dying cells using tritiated thymidine/autoradiography to examine their "birthdates." We show that in control epithelia 25-30% of the degenerating (pyknotic) cells were located in the basal quarter of the epithelium, the location of the least mature sensory neurons and of neuronal stem cell proliferation. Birthdate analysis shows that 2-5% of the degenerating cells were dying within a day or less of their "birth." Thus, a sizeable proportion of these cells were dying precociously, before achieving full neuronal maturation. A further 65% of the dying cells occurred in the middle half and 7% in the apical quarter of the epithelium. Following unilateral olfactory bulbectomy, a two- to threefold increase in the number of degenerating cells occurred in ipsilateral versus contralateral tissue. This was maintained through the 7-week experimental period. A shift of 10-15% of the total degenerating cell numbers from the basal to middle region of the epithelium also occurred. Despite the increased degenerative activity ipsilaterally, the proportion of dying cells labeled autoradiographically remained the same on both sides at most labeling periods. However, a striking wave of enhanced cell death of 6- to 7-day-old neurons over the contralateral levels occurred ipsilaterally in both the 12-day and 7-week postbulbectomy animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Animals; Autoradiography; Cell Death; Cell Survival; Epithelial Cells; Kinetics; Nerve Degeneration; Neurons, Afferent; Nose; Olfactory Bulb; Rats; Thymidine; Time Factors; Tritium

Removal of the sensory plate in Xenopus laevis embryos was performed to study the influence of the olfactory anlage on the development of the forebrain. Embryos, which at stage 22-23 underwent removal of the olfactory anlagen, were killed from stage 47 to 60. In 79% of the animals, two olfactory organs reformed and gave origin to two olfactory nerves which contacted the forebrain. In this instance, the telencephalic hemispheres developed normally. In 14% of the animals, one olfactory organ reformed which contacted the brain by means of one olfactory nerve. This resulted in the development of a unique, reduced in size, cone-shaped telencephalic lobe. In the remaining animals, only a rudiment of the olfactory organ, unconnected with the brain, was present; in these cases, the telencephalon did not develop. Similar results were observed in embryos where olfactory anlagen removal was coupled with damage to, or partial removal of, the prosencephalic vesicle. In animals where lesion of the forebrain was performed without placodal removal, normal development of the forebrain was observed. The developmental relationship observed between the olfactory organ and the forebrain suggests an active role of the nose on the development of the brain.

Topics: Animals; Embryo, Nonmammalian; Larva; Nerve Degeneration; Nerve Regeneration; Nose; Olfactory Nerve; Prosencephalon; Telencephalon; Xenopus laevis

To obtain the neuroanatomical information on the role of the snout sensory input in mastication, the present study was conducted on young and adult mice, young Wistar rats and adult Japanese shrew-moles. The animals were subjected to unilateral and bilateral infraorbital nerve transection. Transganglionic degeneration was studied by the Nauta method and electron microscopy including HRP application to the neck muscles. Transganglionic degeneration was found in every experimental case. 1. Transganglionic degeneration of the fibers was found not only in the main sensory nucleus and spinal tract nucleus of the trigeminal nerve but throughout the cervical and the upper part of the thoracic spinal cord. 2. These transganglionically degenerated fibers descended bilaterally through the cuneate nucleus and then caudally through the posterior funiculus at the obex level. They then entered the dorsal and ventral horns to make a synaptic contact with the degenerated synapses on the dorsal horn cells and with the multipolar cells in the ventral horns. This neuroanatomical information suggests: 1) that the trigemino-neck muscle reflex will be generated monosynaptically by the primary neurons arising from the snout sensory organs and 2) that these primary neurons may play a large role as a neuronal bridge in connecting the masticatory reflex system and the cranio-neck reflex system.

Topics: Animals; Axons; Horseradish Peroxidase; Medulla Oblongata; Mice; Microscopy, Electron; Moles; Nerve Degeneration; Neurons, Afferent; Nose; Orbit; Pons; Rats; Spinal Cord; Trigeminal Nerve

To examine whether the interference of the snout sensory input causes neuromuscular dysfunction in the murine neck muscles, the fine structure of the dorsal neck muscles was studied by electron microscopy. The infraorbital nerves were bilaterally transected in the adult ICR mice (one-month-old), and the animals were sacrificed after postoperative periods ranging from six to 18 months. Alpha motor end-plates showed remarkable changes characterized by shrunken synaptic boutons containing abundant lysosomes and/or disappearance of the synaptic boutons. The changes in the muscle spindles were characterized by the sarcolemmal undulation of the intrafusal muscle fibers and the frequent appearance of lysosomes in their sensory terminals. These degenerative changes were observed between nine months and 18 months after neurotomy and intensified with the length of the postoperative period. From the results of the present study, it was concluded that a reflex pathway exists between the snout receptor organs and the dorsal neck muscles.

Topics: Afferent Pathways; Animals; Lysosomes; Mice; Mice, Inbred ICR; Microscopy, Electron; Motor Endplate; Muscle Spindles; Muscles; Neck; Nerve Degeneration; Nose; Reflex; Sarcolemma; Sensory Receptor Cells; Synapses; Time Factors

Topics: Animals; Ganglia; Histocytochemistry; Incisor; Male; Mandibular Nerve; Maxillary Nerve; Molar; Mouth; Nerve Degeneration; Nissl Bodies; Nose; Rats; Tongue; Trigeminal Nerve

Topics: Animals; Beak; Body Weight; Bone and Bones; Cerebrospinal Fluid; Chickens; Epithelium; Female; Male; Manometry; Nerve Degeneration; Nervous System; Nose; Periosteum; Spinal Canal; Vitamin A Deficiency