Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0599766 (functional recovery)
 13,441 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Neuronal populations projecting to a common target may compete for neurotrophic substances. To determine if competition impairs target reinnervation, we examined the effect of capsaicin-induced sensory denervation on sympathetic nerve ingrowth to the sympathectomized rat superior tarsal smooth muscle. In tarsal muscles with intact sympathetic innervation, capsaicin injection on Day 2 reduced numbers of perimuscular CGRP-ir sensory nerves by 68% at 3-4 months; however, it did not alter dopamine-beta-hydroxylase-ir nerve density, response to nerve stimulation, or tarsal muscle adrenoceptor-mediated contraction. Tarsal muscles denervated by ipsilateral superior cervical ganglionectomy on Postnatal Day 4 were partially reinnervated by fibers from the contralateral ganglion, as noted in previous studies. Sensory denervation by capsaicin improved sympathetic reinnervation, as evidenced by a 174% increase in numbers of DBH-ir nerves and a 62% increase in neurally mediated smooth muscle contraction evoked by electrical stimulation of the contralateral pathway relative to reinnervated muscles of vehicle-injected rats; smooth muscle function was also influenced, as indicated by a decrease toward normal in adrenoceptor sensitivity. Tarsal muscles denervated at 30 days were not reinnervated in either vehicle-injected or capsaicin-treated rats, indicating that sensory denervation does not extend the developmental window during which contralateral reinnervation can occur. Both the vehicle-injected and capsaicin-treated preparations with sustained juvenile sympathectomy showed sensory hyperinnervation as adults; thus, a chronic reduction in competition from sympathetics is a sufficiently powerful stimulus to overcome the decreased nerve density induced by neonatal capsaicin treatment. We conclude that sensory nerves limit the extent of sympathetic reinnervation and functional recovery that can occur following neonatal sympathetic denervation.
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PMID:Sensory nerves impair sympathetic reinnervation and recovery of smooth muscle function. 139 80

Deafferentation of certain brain regions in adult animals results in (1) the disappearance of degenerating axon terminals and (2) in the temporary persistence of vacant postsynaptic sites. These postsynaptic sites were shown to be re-supplied by sprouted axon terminals of intact axons. It is described in this paper, that in brain regions (e.g. cerebellar cortex, lateral geniculate nucleus) where axonal sprouting of local elements or of persisting afferent axons is negligible or absent, synaptic reorganization occurs via the active participation of postsynaptic dendritic and somatic elements of surviving local nerve cells. The dendrites may develop two types of reaction upon deafferentation (1) formation of presynaptic specializations along their otherwise "classical" postsynaptic membrane, resulting in the formation of new, dendro-dendritic synapses and (2) the "adaptive" (structural) reduction in size of denervated nerve cell dendritic arbor, leading to a relative increase in density of the surviving (though non-sprouting) afferent axon terminals. A partial functional recovery in both cases is also demonstrated.
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PMID:Morphological plasticity of dendrites in adult brain. 213 Jun 32

The callosal transfer of information to the visual cortex following its unilateral deafferentation from its geniculate input was studied in both hemispheres. Deafferentation was performed in adult cats by sectioning the optic tract. Action potentials of single cortical cells and visual evoked potentials were recorded from area 17-18 boundary in acute and chronic operated cats. In the deafferented hemisphere, cortical cells were usually visually inactive. However, some recovery of function took place in this hemisphere in the chronic cats, as expressed by the increase in the proportion of S-cells. In the intact hemisphere diminution of responsiveness and reduction of selectivity to the stimulus orientation and direction were found. The responsiveness and selectivity level in the intact hemisphere increased with postoperative time. The ocular dominance distribution in this hemisphere was similar to that of our normal control cats. The characteristics of the visual evoked potentials were in keeping with the hemispheric dominance of the cortical cells found in the experimental cats. It was concluded that a plasticity related mechanism is involved in the recovery of callosal activation of visual cortical cells following deafferentation.
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PMID:The deafferented visual cortex: neuronal activity and visual evoked potentials. 361 Apr 95