Oxidative events in neuronal and glial cell-enriched fractions of rat cerebral cortex

The aim of this work was to investigate how neurons and glial cells separated from rat brain cortex respond to “in vitro” oxidative stress induced by incubation of the cellular fractions in the presence of prooxidant mixtures; in addition, the endogenous enzymatic antioxidant capacity of the purified fractions was investigated. Neuronal and glial cell-enriched fractions were obtained from rat cerebral cortex following passages of the tissue through meshes and centrifugations. The following parameters were evaluated: antioxidant enzymes superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPx), and glucose-6-phosphate dehydrogenase (G6PDH); lipid peroxidation products (TBARS) prior to (basal) and after (iron-stimulated) incubation with a mixture of iron and ascorbic acid; intracellular production of reactive oxygen species (ROS) using a fluorescent probe, dichlorofluorescin-diacetate, in basal, iron-stimulated, and menadione stimulated conditions. SOD and GSHPx activities showed no significant changes between neurons and glia, whereas CAT and G6PDH activities were found to be significantly lower in glia than in neurons. TBARS levels were significantly lower in the glial fraction than in neurons, both in basal and iron-stimulated conditions. ROS production showed no differences between neurons and glia in both basal and menadione-stimulated conditions. Iron-stimulation produced a marked increase in ROS production, limited to the neuronal fraction, with the glial values being similar to the basal ones. Our conclusion is that glia and neurons isolated from rat cerebral cortex show a similar pattern of the most important antioxidant enzymes and of their basal ROS production, whereas glia is more resistant in “oxidative stress” conditions.     

Neuropeptides and cerebral electric activity in rabbits

The effects of some neuropeptides infused into the cerebral ventricles on the spontaneous cerebral electric activity were studied in unanasthetized rabbits. The following peptides were investigated: physalaemin, caerulein, bombesin, litorin (supplied by Farmitalia). The rabbits were prepared according to Monnier and Gangloff's [10] method in order to record the spontaneous cortical activity. Each of these substances affects the electroencephalographic (EEG) records in a specific and dose-related way. Bombesin induces a biphasic pattern (synchronization followed by a partial activation), litorin is partially activating and physalaemin brings about a marked desynchronization. In spite of the marked structural analogy between bombesin and litorin, their EEG effects differ.     

Silicon: A neglected micronutrient essential for bone health

Bone matrix is predominantly made up of collagen, and in vitro and in animal models studies have shown that silicon is linked to glycosaminoglycans and plays an important role in the formation of cross-links between collagen and proteoglycans, determining the beneficial effects on strength, composition, and mechanical properties of bone. However, there are still no precise indications regarding a possible role of silicon on bone health in humans. Given this background, the aim of this narrative review was to consider the effectiveness of silicon dietary intake and silicon dietary supplementation (alone or with other micronutrients), in order to suggest a daily dosage of Si supplementation, on bone mineral density in humans. This review included eight eligible studies: four regarding dietary intake and four considering supplementation with silicon alone or with other nutrients. Despite the number of studies considered being low, the number of subjects studied is high (10012) and the results are interesting. Although to date the available scientific evidences are not considered valid enough to allow to establish an adequate level of Silicon intake, based on extrapolations from the data obtained with studies on animal and human models, it has been suggested that an adequate intake in order to promote beneficial effects for bone could be considered to be around 25 mg silicon/day. As for silicon dietary supplements, it has been shown that the combined treatment with orthosilicic acid (6 mg), calcium, and vitamin D has a potentially beneficial effect on femoral BMD compared to only use of calcium and vitamin D.     

Long-term treatment with lithium salts and cerebral electric activity. Experimental research

An eeg study was carried out in rabbits to investigate the neurophysiological effects of chronic lithium clorure treatment. The Monnier and Gangloff's stereotaxic method was used for recording cortical and deep structure activity. Lithium clorure was administered i.p. at doses of 20 mg/Kg/die for 15-22 days (mean plasmatic levels: 0.04 mEq/l). The eeg changes consisted in synchronization of the cortical activity, slowing of the deep structure activity and increase of CAD spiking. The most interesting finding was the appearance of peculiar periodic spikes in the CAD and subcortical structures. A similar pattern has been previously described by us in rabbits treated with repeated ECT.     

Centrally administered N-terminal fragments of ACTH (1-10, 4-10, 4-9) display convulsant properties in rabbits

Electroencephalographic and behavioral effects of the following ACTH fragments: 1-4, 4-9, 4-11, 1-10, 4-10, 1-13, 1-17 and 1-24 were studied in rabbits. Sequences 4-9, 1-10 and 4-10 displayed some epileptic properties, i.e., they induced epileptic seizures (only electrographic or also behavioral) or increased hippocampal spiking. The 4-9 sequence seemed to be the common sequence responsible for these proconvulsant effects. The possible involvement of the enkephalinergic system is discussed.     

Synchronizing, sedative and anticonvulsive effects of centrally administered somatostatin in the conscious rabbit

The effects of intracerebroventricular injection of somatostatin-14 on the cortical and deep structure electrical activity, somatic behavior and rectal temperature, were studied in 45 unanesthetized rabbits. In addition the antiepileptic action of the peptide was tested in these models: pentamethylenetetrazole-induced cortical spikes and waves, epileptic focus by topical application of strychnine and voltage-threshold for amygdala after-discharge. The results indicate that somatostatin exerts synchronizing, sedative and weak antiepileptic effects when centrally administered to rabbits.