Biochemical mechanisms and management of choreiform movement disorders

Comparative disposition of dimethylaminoethanol and choline in rats and mice following oral or intravenous administration

Dimethylaminoethanol (DMAE) and its salts have been used to treat numerous disorders in humans and hence safety of its use is a concern. DMAE is a close structural analog of choline, an essential nutrient. Exposure to DMAE may affect choline uptake and synthesis. The current investigation characterizes: 1) the absorption, distribution, metabolism, and excretion (ADME) of DMAE in Wistar Han rats and B6C3F1 mice following a single gavage or intravenous (IV) administration of 10, 100 or 500 mg/kg [¹⁴C]DMAE, and 2) the ADME of [¹⁴C]choline (160 mg/kg) and the effect on its disposition following pre-treatment with DMAE (100 or 500 mg/kg). In both rats and mice, following gavage administration, DMAE was excreted in urine (16-69%) and as exhaled CO₂ (3-22%). The tissue retention was moderate (21-44%); however, the brain concentrations were low and there was no accumulation. Serum choline levels were not elevated following administration of DMAE. The DMAE metabolites in urine were DMAE N-oxide and N,N-dimethylglycine; the carcinogen, N-N-dimethylnitrosamine, was not detected. The pattern of disposition of [¹⁴C]choline following gavage administration was similar to that of [¹⁴C]DMAE. Prior treatment with DMAE had minimal effects on choline disposition. The pattern of disposition of [¹⁴C]DMAE and [¹⁴C]choline following IV administration was similar to gavage administration. There were minimal dose-, sex- or species-related effects following gavage or IV administration of [¹⁴C]DMAE or [¹⁴C]choline. Data from the current study did not support previous reports that: 1) DMAE alters choline uptake and distribution, or 2) that DMAE is converted into choline in vivo.

Atypical and conventional depot medications

The introduction of atypical antipsychotics created a therapeutic dilemma between choosing the oral novel antipsychotic or the conventional depot form. Clinicians want the advantages of both, resulting in higher levels of polypharmacy. Modern psychiatry is probably in a transitional stage from the depot culture to safer oral medications or even to a safer depot culture.

Trihexyphenidyl (artane) abuse among Saudi psychiatric patients

This preliminary study done by abstracting relevant data from different testing material and using multiple rating scales, describes the sociodemographic variables, psychopathological correlates, and features of trihexyphenidyl (artane) abuse in a sample of 14 Saudi psychiatric patients and, as a result of this research, various relevant issues have been discussed.

Benign hereditary chorea. A case report

A case of benign hereditary chorea is reported, along with a brief review of the condition. It is a rare and little known autosomal dominant disorder which may be confused with Huntington's chorea, which has a more serious prognosis. The case described shows some characteristic features. It is difficult to decide how many of the patient's psychiatric difficulties are a reaction to his disabilities and how many have an organic substrate.

Glutamate and Huntington's disease

Very small injections of kainate (an analogue of the neurotransmitter, glutamate) into rat neostriatum have been shown to duplicate remarkably well neural and behavioural abnormalities seen in Huntington's disease (HD). This experimental procedure provided an excellent model system for investigating the pathogenesis and treatment of HD. Work with the animal model has suggested that abnormal glutamate neurotransmission may underline the neuropathological changes found in HD. At present, research is being performed on all aspects of this hypothesis in order to find possible beneficial treatments for sufferers of the disease.

Kainic acid injections in the striatum alter the cataleptic and locomotor effects of drugs influencing dopaminergic and cholinergic systems

Rats with bilateral injections of kainic acid into the striatum were tested for their motor responsiveness to drugs influencing dopaminergic and cholinergic systems. The kainic acid-induced lesions potentiated the locomotor response to both the dopaminergic agonist, d-amphetamine, and the cholinergic antagonist, scopolamine, attenuated the cataleptic response to the dopaminergic antagonist, haloperidol, and potentiated the cataleptic acid and convulsive responses to the cholinergic agonist, pilocarpine. The analogy of these pharmacological effects with those induced by similar drugs in patients with Huntington's disease supports the view that this animal preparation is a useful model of Huntington's disease. The opposite effects of haloperidol and pilocarpine on catalepsy in kainic acid-lesioned rats suggest that more work should be done to elucidate the mechanism behind this conflict before full support can be given to its use as a model system for evaluating possible pharmacotherapy in Huntington's disease.