Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0028738 (nystagmus)
 7,431 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Removal of a vestibular organ deprives the ipsilateral vestibular nuclei of tonic excitatory inflow from vestibular afferents, and thus evokes a central asymmetry, that is imbalance between tonic activity of the left and right vestibular nuclear complexes. In the present study, the effect of the central asymmetry upon a function of different motor systems was investigated in the freely behaving rats subjected to unilateral or bilateral labyrinthectomy (UL or BL). In four sets of experiments the following results have been obtained. 1. Seven UL-evoked symptoms (which reflect impairment of different motor systems) were qualitatively characterized. The short-lasting symptoms were: (1) body twisting, (2) rolling, (3, 4) extension of the fore- and hindlimb contralateral to UL, and (5) circling. These symptoms disappeared in a fixed order during recovery from anesthesia. During of expression of the symptoms was very short (< 1 hour) with the Halothan anesthesia and much longer (approximately 8 hours) with the chloral hydrate anesthesia. The long-lasting symptoms were (6) spontaneous ocular nystagmus, that persisted for 3 days after UL, and (7) head roll tilt, that persisted for at least several weeks after UL. 2. In BL-animals, stimulation of one of the 8th nerves was performed (by means of an implanted electrode; pulses 0.3 ms, 50 Hz, current up to 400 microA). By increasing gradually the strength of the stimulating current, we could evoke all the UL-symptoms but generally in the order (7-->1) which was the reverse as compared to the order of disappearance of the corresponding symptoms during recovery after UL (1-->7). These findings suggest that different symptoms need different levels of the central asymmetry for their appearance, and these levels also determine the order of disappearance of the symptoms during recovery from UL. 3. In UL-animals, by stimulating the 8th nerve on UL-side with a properly adjusted current (200-400 microA) we could immediately abolish all the symptoms except (6), which was, however, considerably reduced. This finding suggests that stimulation of the 8th nerve in UL-rats restores the central symmetry, which results in a concerted disappearance of almost all symptoms. In addition to the intermediate effects, stimulation of the 8th nerve in UL-animals resulted in a long-lasting effect, that is a reduction of the head roll tilt which persisted for at least 10 days after stimulation. 4. In BL-animals bilateral stimulation of the 8th nerve resulted in restoration of the muscular tone, and in considerable improvement of the control of the head position.
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PMID:The role of tonic vestibular input for postural control in rats. 917 27

This study tests the hypothesis that activation of protein kinase C (PKC) is a critical step for early recovery from spontaneous nystagmus after unilateral ablation of the vestibular periphery. Halothane-NO(2)-O(2)-anesthetized Long-Evans rats received a 5-microl intracerebroventricular bolus of vehicle (distilled water, six rats), PKC inhibitor [Iso-H-7 (10 mM, four rats; 50 mM, five rats) or bisindolemaleimide I (Bis-I, 10 microM six rats)], PKG and PKA inhibitor (A-3, 1 mM, six rats), or the serine-threonine protein kinase inhibitor H-7 (1 mM, five rats; 10 mM, five rats). Surgical unilateral labyrinthectomy (UL) was completed within 15 min. Sham control groups showed no nystagmus. Bis-I and Iso-H-7 significantly retarded the disappearance of spontaneous nystagmus quick phases for 8 h after UL (p<0.05). The effects of Iso-H-7 were dose-dependent: more nystagmus quick phases (p<0.05) were present in the 50 mM than the 10 mM group at 7 and 8 h post-UL. The rats given A-3 showed a delayed retardation of nystagmus loss, which differed significantly (p<0.05) from controls at 4-8 h after labyrinthectomy. The number of nystagmus quick phases was significantly greater than controls (p<0. 05) in the 10 mM H-7 group at 4, 5, 6 and 48 h post-UL, but only at 6 and 24 h post-UL in the 1 mM H-7 group. Thus, PKC activation is an important early requirement for vestibular compensation during the acute post-labyrinthectomy period, while cyclic-nucleotide dependent kinases may be important in a later time frame.
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PMID:Protein kinase C inhibition blocks the early appearance of vestibular compensation. 1052 48