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PubMed1990

[The characteristics of the synaptic reorganization in the sensorimotor cortex of cats after the destruction of the symmetrical portion of the cortex in the opposite hemisphere].

Intracellular recording technique has been used to study reactions of corticospinal neurons (CSN) to stimulation of the ipsilateral ventrolateral nucleus (VLN) of the thalamus in acute experiments on adult intact cats and on cats after lesion on the contralateral sensorimotor cortex (exposition from 6 months to 1.5 years). Acceleration of the monosynaptic EPSPs rise phase in slow CSN was revealed in operated animals, which presumed the reorganization of the synaptic contacts in the SD membrane of flow CSN. Detailed analysis of features and branching of CSN axon, collaterals passing to VLN of the thalamus and participating in formation of the ipsilateral pyramidal tract was made by the method of collision test. The significance of the plastic synaptic reconstruction in the ipsilateral thalamo-cortex reverberating system during the outflow formation under conditions of the partial cortex interhemisphere deafferentation is discussed.

Animals↗

PubMed1986

A study on the microvasculature of the cerebral cortex. Fundamental architecture and its senile change in the frontal cortex.

The arterial architecture of the cerebral cortex and its changes along with aging were studied by microangiography, vascular staining, and scanning electron microscopy. The arteries distributed in the cerebral cortex and medulla were classified into cortical, subcortical, and medullary arteries. The cortical arteries were further classified into superficial, middle, and deep cortical branches according to the site of their termination. There were many fountain-like rami in the middle and deep cortical branches. These fountain-like rami were composed of several to many fine arteries, ramified from a small artery by repeated bifurcation within a short segment of its course. This structural pattern is probably responsible for the ease with which pronounced ischemic state may develop in their territories nourished by these branches, and they may play a significant role in the development of pseudolaminar necrosis of the cerebral cortex. Intertwining of small branches forming rope-like structures was observed with increasing frequency with age, suggesting that this phenomenon correlates with aging or is associated with brain atrophy. The intertwining was always clockwise when looking from the proximal side of the arteries towards their distal end. While the precise mechanism of the development of the intertwining remains unclear, torsion of the trunk of the blood vessels is thought to be the cause of the intertwining of the peripheral branches.

Adolescent↗

PubMedDate not supplied

[The involvement of the cerebral cortex, hypothalamus, pituitary and adrenal cortex in the development of periodontosis].

The authors emphasized in parodontosis patients functional alterations of hypothalamic centres with phagocytosis-stimulatory, vasomotor and neurotrophic functions and disturbances of the functional relationship between the hypothalamus (H), the ascendent reticular formation (RF) and the cerebral cortex (CC). Stimulatory therapy of this areas, especially by direct stimulation of the H improves the hypothalamic functions, the relationship between H and the RF and all the clinical status of parodontosis patients. In rabbits with experimental parodontosis have been found functional and histological alterations in cerebral cortex, and especially in hypothalamus, together with lesions in the hypothalamo-posthypophyso-neurosecretoric system, in the anterior pituitary (P) cells (for ACTH, TSH and FSH) as well as in zona fasciculares of the adrenal cortex (AC). This data, together with findings of other authors, prove that parodontosis is a diencephalopathy involving a whole system: CC-H-P-AC.

Aggressive Periodontitis↗

PubMed1985

[Modulating influence of the 2d somatosensory cortex of the cerebral cortex on the effects of electroacupuncture on the trigeminal nuclei].

The effect of reversible functional inactivation of the second somatosensory cortex of the cerebral hemispheres on changes in the transmission of the afferent signals in the trigeminal nuclei after electroacupuncture was studied in acute experiments on adult cats anesthetized with hexenal (59 mg/kg i. p.). After functional inactivation of the second somatosensory cortex electroacupuncture failed to facilitate the evoked potentials in the oral trigeminal nucleus by stimulation of the tooth pulp and the lip of the mouth. In the caudal nucleus, the inhibitory effect of electroacupuncture on noxious stimulation decreased. The involvement of this brain cortex in the mechanisms of action of electroacupuncture on functionally different nuclei is discussed.

Acupuncture Therapy↗

PubMed1983

[Functional relations of the adrenal cortex, thyroid and pineal body. II. Adrenal cortex reaction following epiphysectomy and administration of melatonin].

Histologic-cytological and morphometrical changes were investigated in the adrenal cortex of male Wistar-rats following pinealectomy and application of melatonin in eu-, hypo-, and hyperthyroid situations. A rat experiment (at an average of 45 d) to find a possible functional connection between the pineal gland and the adrenal cortex was carried out. In the literature, there are only a few of informations about the role of the pineal in regulating ACTH secretion. The results are very contrarily. We found that pinealectomy is connected with a progressive transformation and melatonin with a little regressive transformation in the adrenal cortex. But, it is not evident, that the glomerular zone is activated after both pinealectomy and application of melatonin. In our opinion, the glomerular zone and the secretion of aldosterone increased after as well pinealectomy as melatonin. Application of melatonin diminishes the function of the pineal gland (see group 4-pinealectomy plus melatonin-where was found a progressive transformation). Under these experimental conditions, one can speak of a "pharmacological pinealectomy" after application of melatonin alone. However, the effect of melatonin on the fascicular zone and the glomerular zone is different. The effects of pinealectomy or application of melatonin in combination with methylthiouracil or thyroxin are relatively unimportant.

Adrenal Cortex↗

PubMed1984

Tridimensional study of the deep cortex of the rat lymph node: VIII. The deep cortex units of the athymic nude rat.

The deep cortex of the lymph node of various species actually consists of hemispherical structures, termed deep cortex "units." Each unit is centered under an opening of an afferent lymphatic and comprises a center and a periphery. In a recent work on the nude mouse, we found that the congenital athymic state inhibits the development of the lymphocyte population in the center of the units as well as in a related area of peripheral cortex, and that it also modifies other nodal components. In the present work, we wanted to compare the effects of the athymic state on the rat nodes. Therefore, nodes from various anatomical locations in 8-week-old nude rats were submitted to a tridimensional analysis. The overall effects of the congenital athymic state were found to be comparable in rats and mice. However, marked differences were noticed in the modifications of the node histology, in both species of nude animals. Their significance is discussed together with new findings.

Animals↗

PubMed1986

The medial frontal cortex and gastric motility: microstimulation results and their possible significance for the overall pattern of organization of rat frontal and parietal cortex.

Bilateral intracortical microstimulation (60-90 strains of 0.5 ms pulses at 10 Hz, currents below 50 microA) of medial frontal infralimbic and prelimbic cortical areas in ketamine-anesthetized rats produces clear and consistent decreases in ongoing gastric motility. The majority of responses consists of reductions in gastric tone, reductions in the amplitude of gastric contractions, or combined reductions in tone and amplitude. Bilateral section of the vagus nerves eliminates most of the responses, suggesting that the responses are mediated by this nerve. The effective cortical stimulation zone (the 'visceral motor' cortex) largely overlaps the source of the recently described direct projection from medial frontal cortex to the nucleus of the solitary tract; this pathway may be involved in producing the effect. Connections of this cortex with the limbic system suggest it may be involved in producing physiological responses to stress. The topographical, medial to lateral sequence of cortical functional areas revealed by these and other experiments (visceral motor, frontal eye fields, somatic motor, somatic sensory, visceral sensory) is discussed, as well as the possible implications of this pattern to the question of cortical evolutionary development.

Animals↗

PubMed1986

Adult and embryonic frontal cortex transplants after frontal cortex ablation enhance recovery on a reinforced alternation task.

Damage to the medial frontal cortex in rats results in a learning deficit on a reinforced alternation task. The rate of recovery from this deficit was accelerated by transplantation of either adult or embryonic frontal cortex, provided that a delay was introduced between injury and transplantation. The rates of recovery for both delayed embryonic and adult transplants did not differ from the undamaged group. In contrast, transplants of embryonic frontal cortex immediately after ablation did not accelerate the rate of recovery. The accelerated rate of behavioral recovery on the reinforced alternation task appeared to correlate with transplant survival.

Acetylcholinesterase↗

PubMed1983

Astrocytic development in fetal parietal cortex grafted to cerebral and cerebellar cortex of immature rats.

Pieces of cortex cerebri anlage were dissected out from 16- to 17-day-old fetuses and transplanted to the cortical and cerebellar regions of 5- to 6-day-old rat pups. Twelve animals with grafts in the cortical region and 5 animals with grafts in the cerebellar region were studied 1.5-4 months later. Cresyl violet stained sections revealed no gross difference in either cell morphology, cell density or cell distribution between grafts in the two locations. A molecular layer-like zone was present on all free surfaces of the grafts, whether facing a ventricle or the meninges. The astrocytic development was studied using immunohistochemistry with antibodies against glial fibrillary acidic protein, (GFA), and the S-100 protein. Both antibodies visualized starshaped astrocytes and perivascular membranes surrounding blood vessels. Semi-quantitative measurements as well as computerized image analysis showed that the total amount of GFA-like immunoreactivity was much higher in both types of grafts than in corresponding host cortex cerebri. No differences in amount of S-100-like immunoreactivity could be demonstrated. As S-100 is thought to be a more general astrocytic marker than GFA, this suggests that the difference in GFA-like immunoreactivity is due mainly to an increased amount of GFA within the individual astrocytes. It is concluded that grafts of fetal cortex cerebri pieces to the CNS of young hosts develop a profound astrocytic reaction characterized by an increased amount of GFA-like immunoreactivity.

Animals↗

PubMed1982

Tridimensional study of the deep cortex of the rat lymph node. VI. The deep cortex units of the germ-free rat.

The deep cortex of the normal rat lymph node consists of semirounded lymphocytic structures, termed deep cortex "units," each being centered on the opening of an afferent lymphatic. The aim of the present work was to investigate the morphologic features of the units in germ-free animals, in an attempt to evaluate the influence on natural exogenous antigenic stimulation on the development of the units. For this, the lymph nodes from various anatomic locations from 8-week-old Sprague-Dawley germ-free rats were analysed tridimensionally. The observations revealed that, in comparison with the lymph nodes of normal rats, the units of the cervical and mesenteric lymph nodes of the germ-free animals were underdeveloped, while those of the brachial, inguinal, and popliteal lymph nodes were unchanged. Moreover, the germ-free state modified the units of the mesenteric lymph nodes in a manner not encountered in the remaining lymph nodes. Other morphologic features of the peripheral cortex of the lymph nodes of germ-free rats also differed from those of normal ones. The significance of these differences is discussed with respect to immune responses and the process of lymphocyte recirculation. They are of interest because they support previous proposals regarding some aspects of the functioning of the normal lymph node, accounting for the features of the structures and overall architecture of the organ.

Animals↗

PubMedDate not supplied

Specialization of motor cortex neurons in rabbits under normal conditions and after ablation of the visual cortex.

The activity of motor cortex neurons in instrumental food-acquisition behavior is compared in two control rabbits and in three rabbits after bilateral ablation of the visual cortex. Although the same types of neuron specialization were found in the experimental and control animals, their numerical ratio differed markedly in two out of the three experimental rabbits in comparison with the controls: the number of neurons activated in the act of seizing food was halved, while the number of neurons activated in connection with acts of instrumental behavior doubled. The similarity of the processes underlying behavior learning and recovery is discussed.

Animals↗

PubMed1983

Evidence for an amygdaloid projection to premotor cortex but not to motor cortex in the monkey.

Previous studies in the cat have demonstrated a direct projection from the amygdaloid complex to motor and premotor regions of the neocortex. In the present study both anterograde and retrograde tracer techniques have been used to determine whether a similar projection exists in the monkey brain. We have found that the dorsal, magnocellular division of the basal nucleus of the amygdaloid complex gives rise to a projection to the premotor cortex (Area 6), which terminates principally in layers I and II, and to a lesser extent in layer VI. No component of the amygdaloid complex has been found to project to the motor cortex (Area 4). The amygdaloid projection to Area 6 in the monkey appears to be substantially weaker than other rostrally directed projections from the basal amygdaloid nucleus to orbitofrontal and medial frontal areas, and also relatively weaker than the projection that has been described in the cat.

Afferent Pathways↗

PubMed1984

Reevaluation of motor cortex and of sensorimotor overlap in cerebral cortex of albino rats.

The organization of motor cortex and the sensorimotor overlap zone was examined by in-depth electrical stimulation using micromapping procedures in rats. The cutaneous somatic sensory, as well as the efferent motor projections to the hindlimb and forelimb sensorimotor overlap zone were studied in the same animals. Low-threshold movements were elicited from portions of 3 architectonic areas: the lateral agranular, dysgranular and granular areas. Cutaneous light touch projections occur only within the granular area. Cutaneous projections to, and motor projections from individual punctures in the granular overlap zone did not always involve homologous body parts. The total motor cortex exhibits a general musculotopic pattern of organization.

Animals↗

PubMed1988

Deviations in brain development of F2 generation on caloric undernutrition and scope of their prevention by rehabilitation: alterations in dendritic spine production and pruning of pyramidal neurons of lower laminae of motor cortex and visual cortex.

This is a report of comparison of developmental changes of spine densities on the different categories of dendrites of neocortical pyramidal neurons (V and VI layers of motor and visual areas) of Wistar rat, during 11-150 days of age, under conditions of normal nutrition and under chronic caloric but not protein deprivation. The studied animals were of F2 generation born to parents undernourished to a degree that their weights were only 40-50% of normal control. At such a level they would be active, reproduce, and not morbid. Similar level of undernutrition also continued in the F2 group studied. A group of undernourished animals was also, for rehabilitation, put on normal diet from 21 days of age. Visual and motor cortical area pieces were impregnated by Stensaas' rapid Golgi method. Spines were counted on successive 20-micron segments (I-IV) of both apical and basal dendritic main shafts as well as primary and secondary branches. The spine count per segment (density) in the normal population reached exuberant values by 26-50 days of age and later underwent a progressive decline or pruning by 30-50% or more by 150 days of age. The degrees of exuberance and pruning varied in different categories of dendrites, generally being more conspicuous in motor than visual cortex, and more in basal than apical dendrites. Under the conditions of chronic caloric restriction, the phenomenon of exuberance was retarded and pruning was not observed. On the contrary, there was a progressive increase in the spine densities on both basal and apical dendrites, in motor and visual cortex. By 150 days of age, the spine densities were not only greater than the final counts for respective segments in the normal animal, but even greater than the exuberant counts. Postweaning caloric rehabilitation had only a modest impact against this deviation. Preliminary data (intersections) of dendritic branching also indicated a similar pattern of changes (lag followed by increase), but of a lesser degree. These alterations in neuronal development are interpreted as biological adaptations evoked in shaping the homeostasis of the organism's brain and behaviour by factors of nurture.

Aging↗

PubMed1988

Fetal frontal cortex transplanted to injured motor/sensory cortex of adult rats: reciprocal connections with host thalamus demonstrated with WGA-HRP.

Fetal frontal cortex was transplanted into lesion cavities formed in host motor/sensory cortex of adult rats. Eight to twenty-eight weeks later wheat germ agglutinin conjugated with horseradish peroxidase (WGA-HRP) was injected into host thalamus and the brain was sectioned and reacted using a sensitive TMB procedure. A large amount of fine granular WGA-HRP was detected in most transplants. This could represent anterograde transport demonstrating that injured adult host thalamic neurons sprouted axons into fetal cortical transplants. Conversely, none or very few retrogradely labeled pyramidal neurons were present in the transplants. This indicates that pyramidal neurons in transplants either did not sprout into adult host brain or sprouted such short distances that they did not pick up the WGA-HRP. These results are compatible with the hypothesis that high trophic/growth factor levels in newborn or fetal brain and low levels in adults determine the more extensive connections seen in newborn hosts compared with those in adult transplanted hosts. The data are also consistent with the proposal that adult host brains impair axonal growth. Functionally, the data suggest that although corticofugal effects of fetal cortical transplants in adult host brains are likely to be limited, transplants could exert beneficial trophic effects on adult host thalamic neurons.

Animals↗

PubMed1975

Adrenal cortex adenylate cyclase. Specific binding sites for 5'-guanylyl-imidodiphosphate in partially purified plasma membranes from bovine adrenal cortex.

Specific binding sites for 5'-guanylyl-imidodiphosphate [Gpp(NG)p] have been identified in a partially purified plasma membrane fraction from bovine adrenal cortex. The apparent affinity of Gpp(nh)p at 30 degrees C was 12muM-1 and the concentration of binding sites was 100 pmoles per mg of protein. Binding of Gpp(NH)p is inhibited by Mn2+ greater than Mg2+ greater than Ca2+ and enhanced by low concentrations of the chelators ethylenediamino-tetraacetic acid (EDTA) and ethylene glycolbis-(beta-aminoethylether))-N,N'-tetraacetic acid (EGTA). High concentrations of EDTA are inhibitory and at 2.5 mM EDTA binding of Gpp(NH)p is only 10% of that observed in the absence of the chelator. The bound labeled GTP analogue exchanged only slowly with the unlabeled nucleotide after a steady state has been reached. EDTA also releases the bound labeled Gpp(NH)p from its binding sites. The slow dissociation of Gpp(NH)p can explain the persistent activation of adenylate cyclase observed after pretreatment of bovine adrenal cortex plasma membranes with Gpp(NH)p and subsequent washing. It is suggested that at least parts of these binding sites are identical to the sites identified earlier as regulatory sites for angiotensin high-affinity receptors (Glossmann et. al., 1974a) and for ACTH-stimulated cyclase Glossmann and Gips, 1974).

Adenylyl Cyclases↗

PubMed1987

Depolarization of brain cortex slices and synaptosomes by lithium. Determination of K+-equilibrium potential in cortex slices.

K+-equilibrium potential was determined in brain cortex slices of rat by measuring 86Rb+ distribution between the extra- and intracellular space. The ratio of internal to external Rb+ concentration was 39 +/- 1.8, corresponding to a resting membrane potential of 93.8 mV. Li+ (1-126 mM) decreased the membrane potential in both cortex slices and synaptosomes in a concentration-dependent manner. The presence of 1 mM Li+ was enough to cause a slight but distinct depolarization. During incubation in Li+-containing medium slices took up K+; however, for depolarization the presence of extracellular Li+ seemed to be necessary.

Animals↗

PubMed1987

The physiological identification of pyramidal tract neurons within transplants in the rostral cortex taken from the occipital cortex during development.

Axons from neurons in the occipital cortex transiently extend to the pyramidal tract (PT) during the early postnatal development of rats. Normally, these axons are eliminated by the end of the third postnatal week. However, if a portion of fetal occipital cortex is transplanted to the parietofrontal region in newborn hosts then some neurons in the transplant will extend pyramidal tract axons and maintain them. Intracortical microstimulation and electrophysiological recording techniques were used to identify the physiological characteristics of the transplanted pyramidal tract cells and to determine if motor effects could be elicited from the occipital transplant. Microstimulation of the transplant did not reliably evoke movement but the low density and disarray of PT cells within the transplant might account for this. Recording from within the transplant revealed that the overall cell activity was depressed. We were able to identify neurons within the transplant which responded antidromically to stimulation of the pyramidal tract, indicating that their axons have the capacity to conduct impulses and are therefore likely to have developed some viable connections. The functional significance of such projections remains uncertain.

Animals↗