M Lacour

..Elucidation of the mechanisms of action of betahistine is of particular interest for the treatment of vestibular and cochlear disorders and vertigo...

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..Normal balanced functioning of the human vestibular system is required to achieve an upright stance and locomotion, head and eye stabilization and internal spatial representation; any lesion in this system will disrupt these functions...

..These results indicate that changes in neck muscle activity observed in the acute cats and that recovery found in the compensated animals could result from modifications in neural networks controlling neck musculature, such as the LVN...

..They also support the notion that vestibular compensation relies on visual cues whose substitution role gradually decreases after UVN...

..Because locomotor performance of HG rats is not severely affected, it is concluded that early development of locomotion processes is highly resistant to gravito-inertial changes...

..Betahistine dihydrochloride should contribute to this process by acting on both the presynaptic histamine H3 and postsynaptic histamine H1 receptors...

..In addition, they suggest that unilateral suppression of vestibular information would induce transitory spatial memory disorganization at a high level of information processing...

..Switching strategy by means of a new sensory selection of orientation references may be a fast adaptive response to the lesion-induced postural instability...

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..Finally, when vertical/horizontal references were provided, visual vertical perception was improved in both subpopulations, suggesting that all patients relied on the same allocentric strategy...

..Morphological analysis showed two subtypes of GABAergic neurons: medium and small (30 vs. 10 microm, respectively). This is the first report of reactive neurogenesis in the deafferented VN in the adult mammalian CNS...

..This study demonstrates that betahistine and thioperamide strongly improve the recovery of vestibular functions in UVN cats by interacting with the histaminergic system...

..Indeed, spontaneous nystagmus, posture and locomotor balance were rapidly recovered in the UVN cats treated with thioperamide. These results demonstrate that changes in histamine levels are related to vestibular compensation...

..On the whole, results suggest that the environment experienced by the patients is different after UVN and that a different internal spatial representation is constructed, especially for tasks requiring high levels of spatial processing...

..The effects were both dose- and time-dependent. In conclusion, compensation of both static and dynamic deficits is subtended by long-term adaptive mechanisms that could be facilitated pharmacologically using betahistine dihydrochloride...

..They also strongly suggest that tOKN impairment could be part of the long-term asymmetrical functions reported after unilateral loss of vestibular functions...

..They argue for an increased weight of visual reference frame on locomotor functions when vestibular function is unilaterally impaired...

..This action on the histaminergic system could explain the effectiveness of betahistine in the treatment of vertigo and vestibular disease...

..The present data indicate that visual vertical perception improves when postural control is more demanding. This suggests that postural balance is a key reference for vertical perception, at least up to one month after vestibular loss...

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