Melatonin was tested in an ongoing attempt to find the endogenous antagonists of quinolinic acid, an endogenous convulsant. Among a great number of metabolites that have been tried before, only a few were found (cerulein and quinaldic acid in mice and kynurenic acid in rats). In SHR (bred from Swiss) male mice, intracerebroventricular (i.c.v.) pretreatment with melatonin (1.25-10.0 microg) attenuated (in the descending order of potency) the convulsant effect of i.c.v. administered kainate, quinolinate, glutamate, N-methyl-D-aspartate, and pentylenetetrazole. Melatonin was ineffective against i.p. administered pentylenetetrazole. Systemically (intraperitoneal, i.p.) administered melatonin (12.5-100.0 mg/kg) attenuated the convulsant effect of quinolinate, while the action of other convulsants used remained unaltered. It is suggested that melatonin could be tried against grand mal seizures in epileptic patients.

We performed a roorphometric post-mortemanalysis of the cerebral cortex in 24 patientswith schizophrenia (10 men,58.9+5.2yearsold, 14women64.5+4.3yearsold; age range 25-92 years)and28 agematchedcontrols. Tissue blockswere taken from the superiorfrontal cortex, inferior temporalcortex and occipitalcortex. Subsequently, 20um thicksectionswere preparedwith Globussilverimpregnation as previously described (Valletet all. Corticalthickness (mm)was measured in areas 9, 20 and 18 usinga computerassistedimage analysis systemconsistingof I Zciss-Axioplan microscope, I high sensitivity U1-4036 camera (UIESA Electronic),a COMPAQ Dcskpro386/20 microcomputer, anda SAMBATM 2005 software systemdevelopedbyTITN Inc. (Alcatel, Grenoble,France). Corticalthicknesswas signifICantly reducedin patients with schizophrenia comparedto controls in areas 9 (1.99 ±. 0.06 vs 2.49 ± 0.07) and 20 (2.22 + 0.08 vs 2.71 ± 0.1). Conversely no signifICant