Ricardo Martínez-Rodríguez

Chronic nicotine administration increases NGF-like immunoreactivity in frontoparietal cerebral cortex

Nicotine/nicotine agonists, which have been proposed as therapeutic agents for the treatment of Alzheimers disease and other neurodegenerative disorders, produce a wide variety of effects on the nervous system. Some mechanisms involved remain poorly understood. In this work, immunohistochemical techniques were used to determine the effect of nicotine on nerve growth factor (NGF) in the frontoparietal (motor, somatosensory) brain cortex of the albino rat. Nicotine was chronically administered intraperitoneally using osmotic pumps (0.35 mg nicotine base/kg body weight/day for 14 days). An increase in the number and the immunoreaction intensity of NGF‐like positive pyramidal and nonpyramidal neurons of these cortical areas was observed after treatment. Immunopositive astroglial cells were always seen in sections of treated animals but not in controls. The neuropil of control animals was, in general, devoid of reaction, but in treated animals, immunopositive prolongations were located randomly, some in close association with capillaries. At the electron microscopic level, these prolongations were demonstrated as belonging to neurons (dendrites and axons) and astroglial cells. Nicotinic activation of selected neurons and glial cells seems to trigger NGF/neurotrophic mechanisms, suggesting their use may be of benefit in prevention and treatment of neurodegenerative diseases.

Histochemical study of acute and chronic intraperitoneal nicotine effects on several glycolytic and krebs cycle dehydrogenase activities in the frontoparietal cortex and subcortical nuclei of the rat brain

The effects of nicotine on the activity of different dehydrogenases in frontoparietal regions and subcortical nuclei of the rat brain have been studied using histochemical methods. Nicotine sulphate was intraperitoneally administered in acute (4 mg/kg/day × 3 days) or chronic (ALZET osmotic pump providing 2 mg/kg/day × 15 days) doses. The enzymes analyzed were glyceraldehyde‐3‐phosphate, lactate, malate and succinate dehydrogenases (gly3PDH, LDH, MDH, and SDH, respectively). The results demonstrate that chronic as well as acute administration of nicotine produced strong increases in all these enzymatic activities in the superior layers (I, II and III) of the frontoparietal cortex (cingulate, motor and somatosensory regions); but high increases were not seen in the deeper layers of the cortex or in the subcortical nuclei (substantia nigra, caudate‐putamen, nucleus accumbens or nucleus basalis magnocellularis). These hyperactivities were produced in brain regions with normally low enzymatic activity (cortex), but not in those with great intensity (subcortical nuclei). The results are in rough agreement with previous reports on nicotine‐induced increases in glucose utilization, gly3PDH genic expression and neuronal hyperactivity in the brain cortex; but significant discrepancies between the cortical enzymatic maps and those obtained both in these studies and others on nicotine(N)‐receptor localization have been appreciated. The results support the hypothesis that nicotinic cholinergic drugs can have metabolic, long‐lasting stimulant effects on cortical neurons at specific points (probably layer III pyramidal cells and structures with α7‐N‐receptors) of the cortical circuits that could be of great interest in improving altered cognitive functions that are present in Alzheimer disease, as well as in other less severe mental disturbances. Mitochondrial hyperfunction should also be evaluated as a possible side‐effect (as an oxidative stress inductor) of these kinds of drugs. J. Neurosci. Res. 64:626–635, 2001.

Glycoproteins and polyanions in the synapses of rat and mouse central nervous system.

In the present work, it is investigated the location and characteristics of receptors for Con A in synapses of rat and mouse central nervous system. Negatives charges of synaptic surface are also studied. It is observed the presence of glycoproteins on synaptosomal plasma membrane. Presence of negatives charges homogenously distributed all over the synaptosome surface is also notice. These negative charges are revealed by Colloidal Iron, FeOH++cation and cationized Ferritin. Enzymatic extraction experiments suggest that presence of sulphated mucopolysaccharides.

Histochemical study of mucopolysaccharides in the subthalamic region of rats

Histological sections of the Subthalamic region of rats were treated with solutions of: Toluidin Blue, Thionin, Alcian Blue and Colloidal Iron. The microscopic observation of the histological sections treated with those histochemic reactions showed the existence in the Subthalamic region of three neuronal types, differentiated between them because of the morphologic and histochemic points of view. In the LUYs Subthalamic nucleus was observed only one neuronal type, while in the nucleus of the FORELs field and in the Zona incerta were found two very special types of neurons (alpha and beta) differentiated between them because of their reaction before the Collidal Iron. It is suggested the possibility that those different types of neurons have different functional characteristics.

Histochemical characteristics of diphosphate nucleoside consumption in, cat and rat nervous system

Consumption of diphosphate nucleosides is investigated by histochemical methods in rat and cat nervous system. Results show NDP-ase is effectively in histological sections from animals previously perfused with glutaraldehyde or formaldehyde. Histochemical reaction is increased in presence of Ca++, Mg++, Mn++ or imidazole and inhibited by L-DOPA and Noradrenaline in incubation medium. A comparative study of TPP-ase and NDP-ase activities to dilucidate the identity of both enzymes is described.

In vitro d-amphetamine action on oxido-reductase activity of several rat nervous centres

The action of several concentrations of d-amphetamine on the NADH-tetrazolium reductase histochemical reaction has been studied in several nervous regions of rats. The facts observed have demonstrated that d-amphetamine increases the intensity of the histochemical reaction by its action on NADH-oxido-reductase activity in all nervous regions studied.

Distribution of peripherally stained neurons by the Colloidal Iron histochemical method in albino rat cerebral cortex. A quantitative study

A few stained neurons were demonstrated in several cortical areas by the Colloidal Iron method. The intense positive histochemical reaction was located surrounding the perikaryon and some neuronal branches. A quantitative study demonstrated that the largest percentage of stained neurons was found in III, IV and V layers of the visual and auditory cortex. The number of stained neurons in the auditory cortex was greater than in the visual cortex. Statistically significant differences (Students t-test) were obtained between layers I, II, III and VI of both cortical areas. In other cortical areas studied there were no stained neurons (area insularis ventralis, area entorhinalis and area piriformis).

Histochemical study of the myelin-associated carbohydrates.

Myelin-associated carbohydrates were studied by means of histochemical techniques in the central nervous system of birds and mammals. Polianions in the surface of myelin and in interfascicular oligodendroglia were detected using histochemical techniques. Glycoproteins were studied by means of concanavalin A. The Con-A-PO-DAB sequence was used. Concanavalin-A-binding sites were detected in oligodendroglia and on the myelin surface. Similar results were observed in both birds and mammals. The processes of the interfascicular oligodendroglia also contain carbohydrates. A close association between the carbohydrates of these glial processes and the myelin surface carbohydrates was demonstrated, and their probable identity is assumed.

Separation of specific fractions of synaptosomes by affinity chromatography

The authors describe a new technique for isolation of specific fractions of synaptosomes, on the basis of their surface glycoproteins, by affinity chromatography using lectin-Sepharose columns.

Localization of aspartate aminotransferase and glutamic dehydrogenase in the Edinger-Westphal and oculomotor nuclei of Lacerta lepida

Abstract Sections of mesencephalon which contain the Edinger-Westphal and oculomotor nuclei were incubated in an appropriate medium so as to investigate the localization of aspartate aminotransferase (AAT) and glutamic dehydrogenase (GDH). We have seen a different localization for each of the two enzymes. AAT was found in the nerve fibers and in terminals arranged as perineuronal baskets. GDH was found in neuronal cytoplasm but not in the perineuronal baskets.