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α 2 Adrenoceptors are involved in the regulation of the gripping‐induced immobility episodes in taiep rats
Author(s) -
Eguibar José R.,
Cortés Ma. Del Carmen,
Valencia Jaime,
AriasMontaño José A.
Publication year - 2006
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/syn.20305
Subject(s) - adrenergic receptor , psychology , neuroscience , pharmacology , chemistry , medicine , endocrinology , receptor , biology
In 1989 Holmgren et al. (Holmgren et al. 1989 Lab Anim Sci 39:226–228) described a new mutant rat that developed a progressive motor disturbance during its lifespan. The syndrome is characterized by a tremor in the hind limbs followed by ataxia, episodes of tonic immobility, epilepsy, and paralysis. The acronym of these symptoms ( taiep ) became the name of this autosomic, recessive mutant rat. The taiep rats are neurological mutant animals with a hypomyelination, followed by a progressive demyelination process. At 7–8 months of age, taiep rats develop immobility episodes (IEs) characterized by a cortical desynchronization, associated with the theta rhythm in the hippocampus and changes of the nucal electromyogram (EMG), whose pattern is like rapid‐eye‐movement (REM) sleep. These rats also show an altered sleep pattern with an equal REM sleep distribution. This study analyzed therole of α 2 adrenoceptors in the expression of gripping‐induced IEs in 8‐month‐old male taiep rats. The α 2 adrenoceptor agonists clonidine and xylacine increased the frequency of gripping‐induced IEs whereas the α 2 antagonists yohimbine and idazoxandecreased or prevented such episodes. These findings correlate with the pharmacological observations in narcoleptic dogs and humans in which α 2 adrenergic mechanisms are involved in the modulation of cataplexy. Unexpectedly, the repetitive administration of clonidine resulted in jumping behavior, indicative of phasic activation of extensor musculature. Taken together, our results show that α 2 adrenoceptors are involved in the modulation in gripping‐induced IEs and after the administration of several doses of clonidine produced phasic motor activation. Synapse 60:362–370, 2006. © 2006 Wiley‐Liss, Inc.