Pharmacogenetics of psychoactive drugs

Gastric mucosal damage induced by arecoline seizure in rats

In an attempt to know the relation of seizure and gastric mucosal damage, we challenged arecoline (ACL) centrally to induce seizure and investigated gastric hemorrhagic injury in acid-irrigated stomachs of rats. The protective effects of several drugs also were evaluated. After deprivation of food for 24 h, rats were received laparotomy under diethylether-anesthesia. Both pylorus sphincters and carotid esophagus were ligated. The forestomach was equipped with a cannula for gastric irrigation. After recovery from anesthesia (approximately 1 h), the stomach was irrigated for 2 h with an acid solution containing 100 mM HCl and 54 mM NaCl or the same volume of normal saline. Intracerebroventricular (i.c.v.) ACL (0, 1, 3 or 10 mg/kg dissolved in 10 microl of CSF) was challenged to rats immediately after gastric irrigation. The seizure in rats was produced by ACL in a dose-related manner. The ulcerogenic parameters such as decrease of gastric mucosal glutathione levels and increase of histamine concentrations and lipid peroxide generations as well as the raise of luminal hemoglobin contents and exacerbated mucosal lesions were obtained depending on the doses of ACL challenged. These ulcerogenic parameters produced in ACL (10 mg/kg, i.c.v.) seizure rats were markedly ameliorated by gastric vagotomy or central anticholinergics. Intraperitoneal ketotifen, zinc sulfate, diphenhydramine or cimetidine also produced significant (p<0.05) inhibitions of these ulcerogenic parameters in ACL seizure rats. In conclusion, central ACL seizure may produce gastric oxidative stress and hemorrhagic lesions via vagal nervous activation and histamine release in acid-irrigated stomachs of rats.

Psychopathology and treatment of 30,344 twins in Sweden. II. Heritability estimates of psychiatric diagnosis and treatment in 12,884 twin pairs

We estimated the heritability for inpatient psychiatric treatment, treatment with psychoactive medication, and for psychiatric diagnoses in a randomized sample of 12,884 Swedish twin pairs drawn from the general population for a health survey. We found a genetic contribution to treatment and diagnosis, independent of sex and shared environment. The heritability estimate for inpatient treatment was 0.47, for reported treatment with psychoactive medication 0.49, and for an inpatient diagnosis of neurotic or personality disorder 0.60. No statistically significant heritability was found for the diagnoses of alcohol abuse nor for the heterogeneous group of diagnoses of psychoses. This was probably because of the heterogeneity of cases necessary to form large enough groups for analysis, or ascertainment requiring treatment in a psychiatric unit.

Measuring cholinergic sensitivity: II. Arecoline effects on metabolic activity in pontine regions of rat brain

Brain imaging studies may help to localize areas particularly sensitive to cholinergic agonists. A study in rats using the 2-deoxyglucose method for studying changes in brain metabolic activity was performed. Among regions in the pons/medulla, arecoline, 0.05 mg/kg ip, increased glucose utilization in the dorsal raphe, median raphe, and basilar pontine nuclei without producing behavioral or cardiovascular effects. These brain areas, along with the hippocampus, may be pertinent to studies of muscarinic supersensitivity in humans.

Measuring cholinergic sensitivity: I. Arecoline effects in bipolar patients

In a previous study, bipolar patients were found to be more sensitive than controls to induction of rapid eye movement (REM) sleep by the direct muscarinic agonist arecoline. We have replicated this observation in a new group of patients and controls. However, much overlap between groups was seen. Muscarinic supersensitivity appears to be present in some bipolar affective patients, but the REM induction procedure may not be the optimal method for measuring it.