H3-Receptors Control Histamine Release in Human Brain

The regulation of histamine release was studied on slices prepared from pieces of human cerebral cortex removed during neurosurgery and labeled with L-[3H]histidine. Depolarization by increased extracellular K+ concentration induced [3H]histamine release, although to a lesser extent than from rat brain slices. Exogenous histamine reduced by up to 60% the K+-evoked release, with an EC50 of 3.5 +/- 0.5 X 10(-8) M. The H3-receptor antagonists impromidine and thioperamide reversed the histamine effect in an apparently competitive manner and enhanced the K+-evoked release, indicating a participation of endogenous histamine in the release control process. The potencies of histamine and the H3-receptor antagonists were similar to those of these agents at presynaptic H3-autoreceptors controlling [3H]histamine release from rat brain slices. It is concluded that H3-receptors control histamine release in the human brain.     

Characterization of the 5-Hydroxytryptamine Receptor Modulating the Release of 5-[3H]Hydroxytryptamine in Slices of the Human Neocortex

In the rat brain, the presynaptic 5-hydroxytryptamine (5-HT) autoreceptors located on 5-HT terminals correspond to the 5-HT1B subtype. The presence of a 5-HT receptor probably located on 5-HT nerve endings and modulating transmitter release in the human neocortex has been reported, but its detailed pharmacological characterization is not yet available. On the other hand, receptor binding and autoradiographic results indicate that the 5-HT1B receptor subtype is not present in the human brain. We, therefore, studied the modulation of the electrically evoked release of [3H]5-HT by various 5-HT receptor agonists and antagonists in preloaded slices of human neocortex obtained from 18 patients undergoing neurosurgery. The nonselective 5-HT1A/1B/1D receptor agonist 5-carboxamidotryptamine produced a potent inhibition (70% at 0.03 microM) of the electrically evoked release of [3H]5-HT which was blocked by 5-HT receptor antagonists with the following relative order of potency: methiothepin greater than metergoline = methysergide greater than propranolol. The selective 5-HT1A receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin at 0.1 microM did not modify the electrically evoked release of [3H]5-HT. The 5-HT1A/1B receptor agonist RU 24969 was 10 times more potent at inhibiting [3H]5-HT overflow in the rat frontal cortex than in the human neocortex. The potent 5-HT1B receptor antagonist cyanopinodolol did not modify the 5-carboxamidotryptamine-induced inhibition of the electrically evoked release of [3H]5-HT in slices of the human neocortex, but produced by itself a small inhibition of [3H]5-HT overflow.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cryptic vascular malformations diagnosed by stereotactic biopsies--a preliminary study

A series of 14 cryptic vascular malformations (CVM) deeply situated or localized in functional cortical areas were diagnosed by serial stereotactic biopsies. No history was suggestive of hemorrhage, despite a substantial hematoma being evacuated during biopsy procedures in 4 patients. Retrospectively, CVM without hematoma were found to have certain characteristics that should raise the suspicion as to the correct diagnosis. At the time of discharge from the hospital, only 1 patient had mild aggravation of a preexisting motor deficit, which further improved. Serial stereotactic biopsies provided the required histological diagnosis with relatively low risk.     

Correlation between stereo-EEG, CT-scan and stereotactic biopsy data in epileptic patients with low-grade gliomas

Stereo-EEG activity, which was recorded precisely from the same location as stereotactic biopsies, was studied on 11 patients with low-grade glioma and severe partial epilepsy. The volume of the lesions varied from 6 to 72 cm3 (mean 23 cm3). A very depressed activity was recorded in all the 25 specimens of solid tumor and in more than half of infiltrated white matter. The background activity was still conserved in all 'normal' fragments, while it is never found in solid tumor; sometimes it could be found in the infiltrating tumors of white or gray matter. High voltage theta and delta activity was recorded in neither 'normal' nor solid tumors. We emphasize the importance of considering the stage of evolution when we evaluate the significance of the stereo-EEG activity.     

Stereotactic aspiration of colloid cysts of the third ventricle. Preliminary report

From January, 1979, to July, 1986, 10 patients (6 females, 4 males; 12-59 years, mean 37) with colloid cysts of the third ventricle were treated by stereotactic aspiration (Talairach's method). Five cysts have been completely aspirated. The mean residual volume of the other 5 was 19% of the initial volume. Clinical symptoms completely cleared in all but one patient. The advantages of the procedure are discussed.