Search PubMed⌕ Search

Biomedical subjects

R Sandyk

Publications and source records attributed to R Sandyk.

At least 235 records · Page 13Linked to original sources
PubMed1989

Attenuation of reserpine-induced catalepsy by melatonin and the role of the opioid system.

Several reports have indicated that melatonin influences motor activity in animals and humans. Melatonin has been reported to attenuate the rigidity and tremor of Parkinson's disease. Some of the behavioral effects (e.g., analgesic and anticonvulsant properties) of melatonin have been reported to be mediated through interactions with the endogenous opioid peptides. We investigated the effect of melatonin on reserpine-induced catalepsy in the rat and, additionally, examined whether this effect is modified by opioid peptides. Melatonin was found to attenuate markedly the duration of reserpine-induced catalepsy. These effects were potentiated by administration of the opiate agonist nalbuphine hydrochloride, while naloxone partially reversed the catalepsy reducing effect of melatonin. These findings suggest that the motor effects of melatonin may involve critical interactions with opioid peptides, and support the postulated reciprocal interactions between melatonin and opioid peptides that previously have been demonstrated for the analgesic and anticonvulsant properties of melatonin.

Animals↗
PubMed1989

Increased incidence and severity of neuroleptic-induced movement disorder in pinealectomized rats.

The effects of prior pinealectomy on neuroleptic-induced perioral movements were examined in male Sprague-Dawley rats. Treatment with haloperidol resulted in significantly more severe movement disorder in pinealectomized rats than in unoperated control rats. Subsequent administration of melatonin (4 mg, i.p.) was associated with a nonsignificant reduction of the severity of movements in the pinealectomized rats within one hour. We conclude that pinealectomy facilitates the onset of neuroleptic-induced perioral movements, and suggest that impaired melatonin secretion may be implicated in the pathophysiology of tardive dyskinesia in humans.

Animals↗
PubMed1989

Locus coeruleus-pineal melatonin interactions and the pathogenesis of the "on-off" phenomenon associated with mood changes and sensory symptoms in Parkinson's disease.

The "on-off" phenomenon has been reported to occur in more than 50% of patients with Parkinson's disease after 5 years of treatment with levodopa. Several recent studies have reported an association between the "on-off" phenomenon, concurrent mood changes and sensory symptoms in patients with Parkinson's disease. In these reports, "off" was associated with exacerbation of depression, anxiety and sensory symptoms, while "on" was accompanied by normalization of mood with occasional elation and attenuation in the severity of the sensory symptoms. These observations suggest that the biological mechanisms of the "on-off" interact with mechanisms regulating mood and sensory functions. The "on-off" phenomenon may be related to primary degenerative changes in the locus coeruleus (LC). The emergence of mood changes and sensory symptoms associated with the "on-off" may be facilitated by deregulation of LC-pineal melatonin functions. Administration of noradrenergic agents may be beneficial in attenuating the severity of the motor dyskinesias of the "on-off" while serotonergic drugs alone or in combination with melatonin-release enhancing agents may be useful in the management of the mood changes and sensory symptoms.

Affect↗
PubMed1988

Beneficial effects of imipramine on Tourette's syndrome.

Gilles de la Tourette's syndrome (GTS) is a chronic neuropsychiatric disorder characterized by multiple involuntary motor and phonic tics associated with behavioural disturbances including obsessive-compulsive and aggressive behavior, depression and, rarely, psychosis. The relationship of GTS, presumed to be predominantly a dopaminergic disorder, and depression, presumed to be a noradrenergic-serotoninergic deficiency state, is currently poorly understood. The reports published to date on the effects of tricyclic antidepressants in GTS have been contradictory; while Messiha et al. (1976) used imipramine successfully in one GTS patient, Abuzzahab and Anderson (1973) and Fras (1978) on the other hand, found imipramine to exacerbate GTS symptoms and cautioned its usage in this syndrome. A more recent report suggested that imipramine is useful in GTS patients who exhibit symptoms of attention deficit disorder (Dillon et al., 1985). We report a patient with GTS whose depression and behaviour improved considerably when low-dose imipramine (Tofranil) was added to the regimen of anti-GTS medication. This report suggest that tricyclic antidepressants may be useful adjuncts in the management of GTS, and hints at norepinephrinergic and serotoninergic deficiencies as being components of the pathogenesis of the syndrome.

Child↗