Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0027066 (myoclonus)
 4,275 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To study the regulation of 5-HT1A receptors in the brainstem, the region most relevant to the serotonin syndrome and to serotonin-responsive human myoclonic disorders, we chronically treated rats with various 5-HT1A agonists and labeled 5-HT1A sites with [3H]8-OH-DPAT. Daily injection for 30 consecutive days of 10 mg/kg ip 8-OH-DPAT (pre- and post-synaptic 5-HT1A agonist) significantly decreased 8-OH-DPAT-evoked flat body posture, forelimb myoclonus, and hypothermia compared to chronic vehicle injection. There was no cross tolerance to 8-OH-DPAT in rats chronically injected with ipsapirone or buspirone (presynaptic 5-HT1A agonists). However, none of the 5HT1A agonists significantly altered Bmax of brainstem 5-HT1A binding sites. Chronic injection with other drugs such as 1-propranolol, (+/-) pindolol and spiperone (5-HT1A and 5-HT2 antagonists), methysergide (5-HT1 and 5-HT2 antagonist), and agonists and antagonists at various other 5-HT receptors also had no effect on binding parameters. These data demonstrate lack of cross-tolerance between pre- and post-synaptically acting 5-HT1A agonists and absence of down-regulation of presynaptic 5-HT1A sites at doses which induced tolerance of 5-HT1A-mediated behaviors of the serotonin syndrome. They suggest changes in the post-synaptic cell rather than the receptor recognition site as the mechanism of tolerance.
 ...
PMID:Brainstem 5-hydroxytrytamine1A binding sites are not down-regulated by agonists which induce tolerance in the rat: myoclonus and other serotonergic behaviors. 138 64

A 61-year-old man with presumed Pick's disease was successfully treated with fluoxetine for pathological affect. Severe intermittent, rhythmically repetitive trains of myoclonus developed suddenly the following year. A dystonic-like component involving the shoulder region and a decrescendo frequency pattern were observed. Myoclonus involved the face, palate, shoulder, neck, upper chest and back, diaphragm, hips, and upper extremities, especially on the right side. Movements were not influenced by postural adjustments, startle, or other stimuli. Movements proved insensitive to benztropine but abated with discontinuation of fluoxetine. Rechallenge with fluoxetine or trazodone evoked the movements, whereas clonazepam and chloral hydrate abolished the movements. The pattern of myoclonus is unlike previous reported cases and may relate to activation of serotonin 5HT1A receptors (possibly supersensitive in Pick's disease) or to hypodopaminergia. Although fluoxetine may be useful as adjunct therapy in dementing disorders, caution may be warranted in its use in Pick's disease.
 ...
PMID:Reversible intermittent rhythmic myoclonus with fluoxetine in presumed Pick's disease. 804 77