Opiate receptor localization in rat cerebral cortex.

The differential distributions of [3H]naloxone-labeled and [3H]D-Ala-D-Leu-enkephalin-labeled opiate receptors in rat cerebral cortex were localized autoradiographically and quantified by grain counting and computerized densitometry. In addition, receptor distributions were compared to terminal patterns of thalamocortical projections labeled by axoplasmic transport of [3H]amino acids. Opiate receptors labeled with [3H]naloxone in a mu ligand selectivity pattern show striking laminar heterogeneity and are densest in limbic cortical areas, intermediate in the motor cortex, and fewest in the primary sensory areas. By contrast, opiate receptors labeled with [3H]D-Ala2-D-Leu5-enkephalin in a delta ligand selectivity pattern are much more homogeneously distributed across both regions and laminae within regions. Mu receptors in most cortical areas have density peaks in layers I and VI and each peak shows a density gradient that is sloped within the layer so that the highest densities are at the most superficial and the deepest portions of cortex. In addition, there is an intermediate peak whose laminar position varies depending on the area in which it is found. In rostral agranular cortex, including limbic and motor areas, the [3H]naloxone binding peaks are in layers I, III, and VI. In primary somatosensory cortex, the intermediate peak is in layer Va and in most of remaining homotypical cortex it is in layer IV. Some areas have only bilaminar labeling, in superficial and deep layers; these include portions of the sulcal and retrosplenial cortices. Piriform and entorhinal cortices have dense [3H]naloxone binding only in the deepest layer and show a descending gradient of density toward the superficial layer. The positions of the mu receptor peaks were compared with termination patterns of projections originating in the thalamus. Close correspondence was found between receptor binding in the prelimbic, primary somatosensory, and entorhinal areas and projection terminations arising from the thalamic mediodorsal, posterior, and central medial nuclei, respectively. Although regional variations in [3H]D-Ala2-D-Leu5-enkephalin-labeled receptor density are uncommon, a gradual decrease in the number of sites along the dorsomedial wall of the cortex from anterior cingulate to caudal retrosplenial limbic cortex can be observed. Laminar variations in binding density are small as well; higher concentrations of the peptide binding sites are usually found in the deep cortical layers. These findings emphasize aspects of opiate receptor architecture which may be relevant to identifying cortical "opiatergic" neurocircuitry and raise the possibility of opiate modulation of thalamocortical transmission.

New dopaminergic terminal fields in the motor, visual (area 18b) and retrosplenial cortex in the young and adult rat. Immunocytochemical and catecholamine histochemical analyses.

New dopaminergic terminal fields have been visualized in the rat cerebral neocortex, using two morphological methods based on distinct properties of the dopaminergic system: presence of the first synthetic enzyme, tyrosine hydroxylase, and high-affinity uptake of amines. Tyrosine hydroxylase was used as an immunocytochemical marker after destruction of the cortical noradrenergic system, induced either neonatally by 6-hydroxydopamine or later on by DSP4, and controlled by the absence of dopamine beta-hydroxylase immunoreactivity. The uptake and storage of exogenous amines in tissue sections, in the presence of selective high-affinity transport inhibitors, enabled the specific visualization of the dopaminergic system with fluorescence histochemistry. A dopaminergic innervation of low density was observed along a dorsal sagittal strip which extended from the genu of corpus callosum until about 2 mm behind the splenium and encompassed several distinct cytoarchitectonic areas in the sensorimotor and visual cortex (medial and lateral agranular field, area 18b), as well as in discrete zones of the retrosplenial granular 29c,b, and agranular 29d areas. The distribution of these dopaminergic fields suggested a columnar organization. Several characteristics of the dopaminergic innervation were similar to that of the superficial anterior cingulate cortex (area 24): the laminar distribution to the superficial I-III layers, the secondarily developed varicose aspect in catecholamine fluorescence histochemistry and the delayed postnatal ingrowth in contrast with the early prenatal dopaminergic input to the prefrontal cortex. These similarities suggested that the subpopulation of dopaminergic neurons which provides projections to the anterior cingulate cortex could also contribute to the motor and visual cortex and thus play a role in sensorimotor integration. The predictive value of these results in the ascent of the phylogenetic scale are further considered.

Noradrenaline neuron innervation of the neocortex in the rat.

Noradrenaline innervation of the rat neocortex is studied by glyoxylic acid histochemistry and radioisotopic biochemical analysis. The data indicate that all neocortical areas receive a noradrenergic innervation which is identical in organization but varies in density from area to area. Radioisotopic analysis of catecholamines in the cortical areas studied reveals only the presence of significant levels of noradrenaline. Unilateral locus coerulus ablation greatly diminishes ipsilateral noradrenaline content and fiber innervation in all neocortical areas studied. Detailed histochemical analysis reveals a diffuse plexus-like arrangement of noradrenaline fibers, with each cortical layer having a distinctive pattern of innervation. Single noradrenergic fibers enter layer VI of cortex and branch at all levels to undergo extensive collateralization. Terminal horizontal branching in the molecular layer results in the most dense fiber plexus of all cortical layers. This pattern of noradrenaline innervation is similar to that of other non-specific afferent systems innervating neocortex.

Correspondence between 5-HT2 receptors and serotonergic axons in rat neocortex.

The anatomic relationship between serotonergic (5-HT) axons and 5-HT2 receptors in the rat forebrain was determined by a combined analysis of transmitter immunocytochemistry and receptor autoradiography. High densities of 5-HT2 receptors, localized by the ligand N1-methyl-2-125I-LSD (125I-MIL), are found in neocortex and striatum; these regions also receive a dense serotonergic innervation. Regional variations in the density of 5-HT2 receptors and 5-HT axons correspond closely in most, but not all, areas of the forebrain. In somatosensory cortex (SI), the laminar distribution of 5-HT2 receptors closely matches that of 5-HT axons: in particular, a dense band of 5-HT2 receptors in layer Va of SI is in precise register with a dense plexus of fine 5-HT axons. We have also observed a close spatial relationship between 5-HT2 receptors and fine axons in other areas of the forebrain, suggesting that 5-HT2 receptors may be selectively linked to a particular type of 5-HT axon terminal. Since fine axons of this type have been reported to arise from the dorsal raphe nucleus, it appears likely that 5-HT2 receptors may mediate the effects of dorsal but not median raphe projections.

Decreased levels of an astrocytic marker, glial fibrillary acidic protein, in the visual cortex of dark-reared rats: measurement by enzyme-linked immunosorbent assay.

An antibody to glial fibrillary acidic protein (GFAP) (an immunocytochemical marker for astrocytes) has been used in an enzyme-linked immunosorbent assay (ELISA) to determine the amount of GFAP in three visual regions, the dorsal lateral geniculate nucleus (dLGN), the superior colliculus (SC) and the visual cortex (VC) (area 17) of dark-reared (D), normal (N) and light-exposed (L) rats. In all experiments GFAP was also measured in a control non-visual region, the motor cortex (MC) (area 4). No significant differences were found in GFAP in dLGN, SC or MC between D, L or N rats. However, in the visual cortex, the amount of GFAP in N rats was significantly greater than that in D rats (by 32%).

C-peptide immunoreactive neurons in human brain.

C-peptide/C-peptide-like immunoreactivity was shown to be present in the cytoplasm of the soma and the proximal part of apical dendrites of some pyramidal cells in the Neocortex (Gyrus precentralis) and Hippocampus of man. C-peptide (connecting peptide) is a metabolic product in insulin biosynthesis and its localization in neurons is a proof for extrapancreatic insulin production.

[Changes in the oxygen tension of rat cerebral cortex subsequent to hyperoxia and the protective effect of urea]. / Izmenenie napriazheniia kisloroda v kore mozga krys pri giperoksii i zashchitnom deistvii mocheviny

When breathing with air, pO2 in anesthetized rats was 24.1+/-1.8 mm Hg, while after urea administration it was 19.4+/-1.7 mm Hg. A sharp increase in pO2 was revealed in hyperoxia(911+/-48 mm Hg at 6 atm during first 5 min, and 924+/-38 mm Hg--by the 7th min). The high pO2 was only reduced in 10-15 min after decompression. At a combined action of urea and hyperoxia, pO2 was significantly lower (714+/-52 mm Hg); pO2 in successive cortical layers (0-2400 mcm with a 200-mcm step) was progressively decreasing (from 40.7+/-4.9 mm Hg to 16.0+/-1.0 mm Hg in control, and from 928+/-35 mm Hg to 274+/-64 mm Hg in hyperoxia).

[Spectrofluorimetric study of interaction between acetylcholine and brain proteins]. / Spektrofluorimetricheskoe iccledovanie vzaimodeistviia atsetilkholina s belkami mozga.

Interaction of acetyl-choline in 10(-4) . 10(-12) M concentration with a water-soluble fraction of homogenates of different brain areas (medulla oblongata, pons varolii, sensomotor cortex, dorsal and ventral hippocamp, hypothalamus, amygdaloid nuclei region and septal region) was studied by the spectrofluorimetric method. Fluorescence complexes spectra at excitation wavelength of 280, 296 nm were investigated. It is shown that the ACH addition to the water-soluble fractions results in reduction of the spectrum intensity and in insignificant shift of the fluorescence maxima to a short-wave region. This effect is supposed to be due to ACH interaction with the cholinoreceptor (CHR). The number of CHR in all the brain regions studied is calculated. Good correlation is observed between the regional distribution of CHR and the acetylcholinesterase activity.

[Effect of phenazepam and barbamyl on normalization of the sulfhydryl group content of brain tissue following sleep deprivation]. / Vliianie fenazepama i barbamila na normalizatsiiu soderzhaniia sul'fgidril'nykh grupp v tkani mozga krys posle lisheniia sna.

Rats placed into the rotating cylindrical tretbahn (diameter 50 cm, 2.3 r. p. m.) for 24, 48 and 96 hrs developed the sleep deprivation resulting in elevation of SH-group level for over 20% in mesencephalon and diencephalon. The normalizing occurred within 48 hrs. The high level of brain SH-groups in 24-hr sleep-deprived rats changed insignificantly after 12 hrs of resting. The intraperitoneal administration of phenazepam (1 mg/kg) or barbamyl (70 mg/kg) had no effect whereas their combination normalized the SH-groups level within 12 hrs of rest.

[Dynamics of the bound calcium content of the cerebral cortex after terminating the oxygen supply]. / Dinamika soderzhaniia sviazannogo kel'tsiia v kore golovnogo mozga posle prekrashcheniia snabzheniia kislorodom.

The chlorotetracycline fluorescent probe technique has been for the first time applied to in situstudy based on the contact microscopy of the vital cortex preparation. Changes of calcium bound with membranes included a rapid early decrease of the bound calcium in 5-min anoxia. The process revealed specific features for different layers of the cortex. The role of the early disturbance of intracellular calcium metabolism in mechanisms initiating neural responses to hypoxia, is under discussion.

[Monoamine content in the motor region of the cerebral cortex following damage to the symmetrical area of the opposite hemisphere]. / O soderzhanii monoaminov v motornoi oblasti kory golovnogo mozga posle povrezhdeniia simmetrichnoi zony protivopolozhnogo polushariia.

On 8 cats chronic experiments were carried out to determine (spectrofluorometrically) the content of serotonin, dopamine, and noradrenaline in the sigmoid region of the left cerebral hemisphere on the second, third, forth, fifth, eighth days after the removal of the cortex of the symmetrical region of the right hemisphere. On the second day, at the time of maximum disorders of the locomotor function, dopamine content was found to decrease; there was also a tendency to reduction of noradrenaline and serotonin. On the third, and the fifth--eighth days, at the period of the locomotor activity restoration, there was a rise of serotonin content, whereas dopamine content remained low, and noradrenaline content rose considerably. The role of biochemical changes in the motor region in the mechanisms of locomotor function restoration following symmetrical damage of the large hemisphere cortex is discussed.

[Comparison between changes in the concentration of nerve tissue specific and nonspecific proteins in several brain structures of rats during elaboration of a conditioned bilateral defense reflex]. / Sravnenie izmenenii soderzhaniia spetsificheskogo i nespetsificheskogo dlia nervnoi tkani belkov v neskol'kikh strukturakh mozga krys pri vyrabotke oboronitel'nogo uslovnogo refleksa dvustoronnego izbeganiia.

Comparison of the time course of the content of brain-specific and brain-nonspecific proteins in five different structures of the central nervous system immediately and one or seven days after the conditioned reflex development has shown that functions of these proteins seem to be different. They are triggered at different stages of the conditioned reflex development irrespective of the fact that both proteins are likely to be implicated in the processes of information consolidation and storage.

[Age and changes in the concentration of dicarboxylic amino acids and GABA in different portions of the dog cerebral cortex and cerebellum]. / Vozrastnye izmeneniia soderzhaniia dikarbonovykh aminokislot i GAMK v raznykh uchastkakh kory golovnogo mozga i mozzhechke sobak

The content of dicarboxylic amino acids lowers with age in all the structures of cerebral cortex and cerebellum under study when calculating per I g of fresh tissue and 100 mg of protein. The greatest decrease in the amount of glutaminic and aspartic acids is found in the parietal region at the senile age. The content of GABA in all the brain structures of three-year dogs is significantly higher than in the one-year dogs and at the senile age it is somewhat lower as compared to the three-year animals when calculating per 1 g of fresh tissue, the degree of the decrease in all the studied regions being practically the same.

Long term neurotoxicity of styrene. A quantitative study of glial fibrillary acidic protein (GFA) and S-100.

Little information exists about the possible neurotoxicity of styrene. The present study was designed to explore whether long term inhalation exposure (three months) to styrene (90 and 320 ppm) could induce long lasting astroglial alterations in Sprague Dawley rats, traceable four months after exposure ceased. Styrene exposure at 320 ppm induced such alterations as shown by raised concentrations of the glial cell marker, glial fibrillary acidic protein (GFA) in the sensory motor cortex and in the hippocampus. GFA is the structural protein of the astroglial filaments and formation of these filaments has been shown after damage to the central nervous system from any cause. It is concluded that exposure to styrene at moderate exposure levels induces regional, long lasting astroglial reactions that serve as an indicator of solvent induced brain damage.

[Content of N-acetylneuraminic acid in water-soluble and membrane fractions of various fractions from rat brain cortex]. / Soderzhanie N-atsetilneiraminovoi kisloty v vodorastvorimoi i mambrannoi fraktsiiakh tkani raznykh analizatorov kory golovnogo mozga.

The content of N-acetylneuraminic acid (ANA) was measured in the water-soluble and membrane fractions of the visual, locomotory, auditory and sensomotory divisions of rat brain cortex as well as in glycoproteins and glycolipids of the membrane fraction. The content of ANA in the water-soluble fraction of the visual, locomotory, auditory and sensomotory analyzers of brain cortex was 0.55, 0.56, 0.55 and 0.65 mkg/mg of dry weight, respectively. The ANA content in the membrane fraction was 9.2, 8.8, 8.2 and 8.4 mkg/mg of dry weight, respectively. The ANA content in the membrane fraction of glycoproteins was 2.8, 2.4, 2.2 and 2.8 mkg/mg of dry weight, respectively., that in the membrane fraction glycolipids--5.2, 7.2, 5.9 and 5.5 mkg/mg of dry weight, respectively. The ANA content in the membrane glycolipids of the locomotory division of rat brain cortex differed significantly from that of all the other divisions.

An intermittent somatostatin-immunoreactivity in the cortex and basal ganglia of the rat.

Using light microscopic immunohistochemistry, somatostatin-positive structures were observed in the cortex of the rat. These structures, including cells and fibers, are widely distributed in all cortical laminae and are also found in the basal ganglia. The positive results were obtained exclusively in two groups of animals sacrificed during two different months of two subsequent years. The reason for this variability in the immunocytochemical stainability of cortical structures remains enigmatic.