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At least 325 records · Page 18Linked to original sources

PubMed1983

[Functional relations between the adrenal cortex, thyroid gland and pineal body. I. Reactions of the adrenal cortex following interference with the thyroid regulatory cycle].

Histologic-cytological and morphometrical changes were investigated in the adrenal cortex of male Wistar-rats in experimental hypo- and hyperthyroid situation. Under hypothyroid metabolism's situation (methylthiouracil-application or thyroidectomy) a regressive transformation was found: It is a decrease of secretion of the fascicular zone. The glomerular zone was activated. After long-time application of high dosis of thyroxin, the histological findings show some criteria of an increasing function and also of a beginning exhaustion, too. It is evident, that the duration of the hyperthyroid situation is important. Thyroxin is an unspecific stressor. The long-time application of high thyroxin dosis induced a regressive transformation and atrophic changes in the adrenal cortex. The nuclei of the fascicular and the glomerular zone were diminuated significantly.

Adrenal Cortex↗

PubMed1981

[Role of the contralateral cortex on the receptive field properties in the visual cortex of cats].

The aim of this series of experiments was to evaluate the receptive field properties of visual cells receiving part of their input the corpus callosum. Normal (control) and chiasma sectioned cats were recorded using conventional methods. The recording sites were the 17-18 border and the lateral suprasylvian (LS) cortex. The results indicated (a) the ocular dominance distribution was shifted towards the ipsilateral eye in the split chiasma cats; (b) orientation tunning and/or directional specificity were identical for the two eyes; (c) R.F. positions of binocular cells were also similar for each eye and were clustered near the vertical meridian, which they sometimes straddled; (d) R.F. sizes were larger in L.S. than in primary visual cortex but generally of equal dimensions for each eye. The results are interpreted with respect to the various functions which have been postulated for the corpus callosum.

Animals↗

PubMed1978

[The development of the adrenal cortex in pig (Sus scrofa domestica). (A contribution on the development of the fetal interior zone of the adrenal cortex in pig) (author's transl)].

The adrenals of pigs have been investigated histologically and histochemically during different periods of time pre- and postnatally. The pig (Sus scrofa domestica) shows a proper fetal cortex in the prenatal development of the adrenal gland. This involves slowly during the last quarter of pregnancy. A weight reduction is not noted thereby. Just before delivery the adrenal cortex of the pig has been subdivided into a zona arcuata and zona fasciculata. The zona reticularis develops only postnatally.

Adrenal Cortex↗

PubMedDate not supplied

[The neuronal activity of the cat motor cortex during the differentiation between the reactions of placing support on the right and left paws acquired by stimulation of the parietal cortex of either hemisphere].

Cats were simultaneously trained to differentiate two conditioned reflexes: conditions placing of the right and the left forepaws electrical stimulation of the ipsilateral parietal cortices (area 5) serving as a conditioned stimulus (the right and the left areas correspondingly). Single unit responses of the shortest latencies in the motor cortex did not depend upon the cases whether parietal stimulation evoked placing or did not. Excitatory single unit responses occurring within 20-200 ms latency period from the stimulation onset were observed to be present only if the placing reaction was performed on the side controlled by the motor cortex of the given hemisphere. In the absence of conditioned placing after satiation of an animal or if the conditioned placing was performed by the other forepaw these excitatory responses were replaced by inhibitory pauses within the same time limits.

Animals↗

PubMedDate not supplied

[The afferent and efferent connections of field 7 in the parietal cortex with field 18a of the visual cortex in the rat].

By means of administration of horseradish peroxidase to the field 7 in the parietal cortex of rat, studies have been made on antero- and retrograde axonal transport of the enzyme to reveal bilateral connections of this field with the field 18a of the visual cortex. It was shown that the field 18a is a source of afferent fibers which reach the field 7, more evident projections being observed at the ipsilateral side. Labeled neurones in the field 18a were found mostly in layer III, and to a lesser extent-in layer V. Single labeled neurones were also found in layers II and VI. Labeled terminals of efferent fibers originating from cells in the field 7 were located in layers I, II-III and V of the field 18a. Maximum density of the terminals was registered in layer II-III, less one in layer V, and very negligible-in layer I. It should be noted that labeled terminals were revealed in those cortical regions, which contained labeled neurones which gave origin to afferent fibers to the field 7.

Afferent Pathways↗

PubMed1999

Effects of water extract of 1:1 mixture of Phellodendron cortex and Aralia cortex on polyol pathway and oxidative damage in lenses of diabetic rats.

Enhanced activity of the polyol pathway and oxidative damage have been implicated in the pathogenesis of diabetic cataract. We decided to investigate whether these changes in diabetic lenses could be prevented by the water extract of Phellodendron cortex and Aralia cortex (P55A). Aldose reductase activity was inhibited significantly by the treatment with P55A. Consequently, it caused a dramatic reduction in the high sorbitol contents observed in the lenses of diabetic rats. In addition, the greatly elevated content of thiobarbituric acid reactive substances (TBARS) and carbonylated protein in diabetic rats were reduced by P55A treatment. These results suggest that P55A extract exerts an antioxidant effect by reducing lipid peroxidation and protein carbonylation as well as having an inhibitory action against aldose reductase in the lenses of diabetic rats.

Aldehyde Reductase↗

PubMed1984

Inputs from the olfactory bulb and olfactory cortex to the entorhinal cortex in the cat. II. Physiological studies.

Field potentials and unit activity elicited by electrical stimulation of the olfactory bulb (OB) and anterior and posterior prepiriform cortex (PPCa and PPCp) were measured extracellularly in the entorhinal cortex (EC) of the cat. Different topographic distributions of the amplitude and peak latency of average evoked potentials (AEPs) were obtained depending on the stimulated area. The maximal evoked activity in the EC showed a gradient in a latero-medial direction with the extremes corresponding to the stimulation of OB and PPCp respectively. Analysis of firing patterns of units in the EC in response to stimulation of the OB, PPCa and PPCp showed that an appreciable number of units responded to stimulation of different areas, mainly PPCa and PPCp. It was found that the pathways being stimulated differed in conduction velocities with the PPCp-EC being the slowest. Most responding units lay in layer I and II of the EC. The AEPs to PPCa- and PPCp-stimulation presented different types of depth profiles. Stimulation of the PPCa evoked an initial surface-negative depth-positive potential whereas the PPCp evoked a different type of AEP with an initial positive component at the surface and negative in depth. It is assumed that the stimulated fibres have their active synapses at different levels within the superficial layers of the EC. The possibility of direct influence of olfactory inputs on the hippocampus mediated by one synapse in the EC is discussed.

Animals↗

PubMed1982

Development of brain stimulation reward in the medial prefrontal cortex: facilitation by prior electrical stimulation of the sulcal prefrontal cortex.

Electrical stimulation of the medial prefrontal cortex (MC) in rats delivered daily for seven days causes a marked improvement in the rate of acquisition of a self-stimulation response. In the present experiment, we looked at whether we could get the same facilitatory effect on self-stimulation of the MC by delivering pre-training stimulation to other points in the brain anatomically related to the MC. Electrical stimulation of the lateral hypothalamus was without effect. However, electrical stimulation of the sulcal prefrontal cortex (SC) either contralateral or ipsilateral to the MC electrode did facilitate acquisition of self-stimulation of the MC. Thus the Sc and MC would appear to be part of the same substrate controlling the development of positive reinforcement in the MC.

Animals↗

PubMed1982

Elimination of medial prefrontal cortex self-stimulation following transection of efferents to the sulcal cortex in the rat.

Intracranial self-stimulation (ICSS) of the medial prefrontal cortex (MFC) was not affected by lesions of the medial forebrain bundle, the nucleus accumbens or medialis dorsalis. However, bilateral, parasagittal knife cuts that transected fibers interconnecting the medial and sulcal cortices eliminated ICSS from the MFC with no apparent recovery over a 21 day test period. Similar knife cuts produced only transient effects on lateral hypothalamic ICSS. These data suggest that the neural substrates of frontal cortex ICSS are very different than those that subserve ICSS along the medial forebrain bundle.

Animals↗

PubMed1983

Cortex-to-cortex healing after mandibular osteotomy.

Cortex-to-cortex healing is frequently attempted following orthognathic surgical procedures. This paper reports the results of in vivo experiments to investigate the healing process when two cortical surfaces are conjoined and discusses the implications in relation to the surgical correction of mandibular prognathism.

Animals↗

PubMed1996

Development of projections from transplants of embryonic medial or lateral frontal cortex placed in the lateral frontal cortex of newborn hosts.

Several recent experiments using neocortical transplantation paradigms indicated that embryonic neurons grafted in a heterotopic locus retain development characteristics corresponding to their site of origin. In the present study, limited portions of lateral (lateral-to-lateral) or medial (medial-to-lateral) sectors of embryonic (E16) frontal cortex were grafted into the lateral frontal cortex of newborn rats. A retrograde tracer was injected 3-4 months later into the dorsomedial or ventrolateral sectors of the host caudate-putamen (CPU). The results indicate that the mediolateral arrangement of striatal projection developed by lateral-to-lateral transplants is virtually identical to that found in intact rats. A very weak proportion of the transplanted cells distribute fibers to the dorsomedial sector of the CPU. In marked contrast, the proportion of efferents from medial-to-lateral transplants projecting to the dorsomedial CPU is by far larger than the one directed to the ventrolateral CPU. Our findings provide evidence that even within one single neocortical area (the frontal neocortex) some degree of prespecification (medial versus lateral patterns of efferent projections) is already present at E16.

Age Factors↗

PubMed2005

EEG activities in the orbitofrontal cortex and dorsolateral prefrontal cortex during the development of morphine dependence, tolerance and withdrawal in rhesus monkeys.

Investigating the activities of the prefrontal cortex (PFC) in the process of addiction is valuable for understanding the neural mechanism underlying the impairments of the PFC after drug abuse. However, limited data are obtained from primate animals and few studies analyze Electroencephalogram (EEG) in the gamma band, which plays an important role in cognitive functions. In addition, it is yet unclear whether drug abuse affects the orbitofrontal cortex (OFC) and dorsolateral PFC (DLPFC)--the two most important subregions of the PFC--in similar ways or not. The aim of this study is to address these issues. We recorded EEG in the OFC and DLPFC in three rhesus monkeys. All animals received a course of saline (NaCl 0.9%, 2 ml) injection (5 days) followed by 10 days of morphine injection (every 12 h), and then a further series of saline injection (7 days). A main finding in the present study was that morphine decreased EEG power in all frequency bands in a short period after injection in both the OFC and DLPFC in monkeys. And gamma power decreased not just in a short period after morphine injection but lasted to 12 h after injection. Moreover, we found that although the changes in EEG activities in the OFC and DLPFC at 30-35 min after injection were similar, the DLPFC was more sensitive to the effect of morphine than the OFC.

Analysis of Variance↗

PubMed2005

ELISA methods to measure cholinergic markers and nerve growth factor receptors in cortex, hippocampus, prefrontal cortex, and basal forebrain from rat brain.

The central cholinergic system has a fundamental role in normal cognitive function, and in diseases that exhibit cognitive dysfunction. The purpose of this study was to design ELISA methods to measure proteins that have essential functions in the central cholinergic system. We were particularly interested in quantifying proteins that respond directly or indirectly to nerve growth factor (NGF). ELISAs offer advantages over Western blot analyses and other methods, such as increased sensitivity, decreased assay variability, increased efficiency, and decreased cost. We developed indirect ELISA methods for: choline acetyltransferase (ChAT); the vesicular acetylcholine transporter (VAChT); the high affinity choline transporter (HACT/CHT); TrkA, the high affinity NGF receptor; the p75 neurotrophin receptor (p75(NTR)). A sandwich ELISA was developed to measure tyrosine-phosphorylated TrkA in brain lysates. We used these ELISAs to compare levels of the above proteins in important memory-related brain regions--basal forebrain, hippocampus, cortex, and prefrontal cortex--from old and young rats. We identified age-related differences in the levels of the aforementioned proteins (e.g., VAChT and HACT/CHT in hippocampus). Thus, these ELISA methods should be particularly useful for comparing the effects of age, disease, drugs, and toxicants on brain levels of key cholinergic and growth factor-related proteins.

Acetylcholine↗

PubMed2004

Lesions to the basolateral amygdala and the orbitofrontal cortex but not to the medial prefrontal cortex produce an abnormally persistent latent inhibition in rats.

Repeated nonreinforced preexposure to a stimulus interferes with the establishment of conditioned responding to this stimulus when it is subsequently paired with reinforcement. This stimulus-preexposure effect is known as latent inhibition (LI). Rather remarkably, LI appears to be resistant to the effects of numerous lesions, including the prefrontal cortex (PFC) and the basolateral amygdala (BLA). However, intact behavioral expression of LI following damage to given brain regions does not preclude the possibility that such regions participate in the regulation of LI expression in the intact brain. The present study showed that lesions of the BLA and the orbitofrontal cortex (OFC) but not of the medial PFC (mPFC) led to an abnormally persistent LI which emerged under conditions that disrupted LI in control rats. LI was measured in a thirst motivated conditioned emotional response procedure by comparing suppression of drinking in response to a tone in rats which received 0 (nonpreexposed) or 40 tone presentations (preexposed) followed by either two or five tone-shock pairings. Control rats showed LI with 40 preexposures and two conditioning trials, but raising the number of conditioning trials to five disrupted LI. OFC- and BLA-lesioned rats showed LI under the former condition but in addition persisted in exhibiting LI under the latter condition. Rats with lesion of the mPFC did not show persistent LI. Thus, although LI does not depend on the integrity of BLA and OFC (because it is present in BLA- and OFC- lesioned rats even under conditions disrupting the phenomenon in normal rats), these regions play an important role in the modulation of its expression, more specifically, in the control of the non-expression of LI when the impact of conditioning increases beyond a certain level.

Amygdala↗

PubMed1997

p-Chlorophenylalanine and fluoxetine inhibit D-fenfluramine-induced Fos expression in the paraventricular nucleus, cingulate cortex and frontal cortex but not in other forebrain and brainstem regions.

D-Fenfluramine, a putative serotonin releaser and reuptake inhibitor, is commonly prescribed for the treatment of obesity. Brain sites activated by D-fenfluramine have been mapped via the expression of the immediate early gene Fos. However, it is not clear that serotonin release in the brain mediates the effects of D-fenfluramine on Fos expression. The present study determined whether D-fenfluramine induces the expression of Fos in the brain through the release of serotonin. Rats were pretreated either with the serotonin depleting drug p-chlorophenylalanine (PCPA) or with the serotonin reuptake inhibitor fluoxetine. Both drugs inhibited D-fenfluramine-induced Fos expression in the cingulate cortex, frontal cortex, and the parvocellular subdivision of the paraventricular nucleus of the hypothalamus. Neither drug reduced D-fenfluramine-induced Fos responses in several other brain areas, including the caudate-putamen, amygdala, and brainstem regions such as the lateral parabrachial nucleus and nucleus of the solitary tract. These results indicate regional specificity of mechanisms mediating D-fenfluramine-induced Fos expression. It is likely that D-fenfluramine-induced Fos expression at various sites in the brain is mediated via a combination of serotonin release and other, as yet unidentified, neurotransmitters.

Animals↗

PubMed2000

Water extract of 1:1 mixture of Phellodendron cortex and Aralia cortex has inhibitory effects on oxidative stress in kidney of diabetic rats.

Enhanced activity of the lipid peroxidation and oxidative damages have been implicated in the pathogenesis of diabetic kidney complications. We explored to determine whether these changes in diabetic kidney could be prevented by water extract of mixture of Phellodendron cortex and Aralia cortex (P55A). Greatly elevated content of thiobarbituric acid reactive substances (TBARS) and carbonylated protein in kidneys of diabetic rats were significantly reduced by P55A treatment. In addition, abnormally low ratio of GSH/GSSG in diabetic kidneys was elevated to almost normal levels by the treatment with P55A. These results suggest that P55A extracts exert antioxidant effect by reducing lipid peroxidation and protein carbonylation as well as by elevating the ratio of GSF/GSSG in diabetic kidney.

Aldehyde Reductase↗

PubMed2002

Volumetric measurement of the hippocampus, the anterior cingulate cortex, and the retrosplenial granular cortex of the rat using structural MRI.

MRI imaging of the rodent brain is a rapidly growing field in the neurosciences. Relatively limited information is available for regional volume determination. The present paper describes a reliable method for the assessment of the hippocampus, the anterior cingulate cortex, the retrosplenial granular cortex and the ventricles in rats. MRI scans were acquired using a 7 T magnet. The anatomical sampling method was found to be highly reliable with an intra-rater reliability of greater than 0.93. The current protocol should facilitate future in vivo neuroimaging research using animal models of neurodegenerative diseases.

Animals↗

PubMed2005

Neuronal activity dependent on anticipated and elapsed delay in macaque prefrontal cortex, frontal and supplementary eye fields, and premotor cortex.

In macaque monkeys performing a memory-guided saccade task for a reward of variable size, neuronal activity in several areas of frontal cortex is stronger when the monkey anticipates a larger reward. This effect might depend on either the size or the value of the reward. To distinguish between these possibilities, we recorded from neurons in frontal cortex while controlling value through a manipulation of time rather than amount. A cue presented at the beginning of each trial, predicted the length of the delay during which the monkey would have to maintain fixation before performing a saccade and receiving a reward of fixed size. Predicting a short delay had effects closely similar to those of predicting a large reward: 1) monkeys were more motivated when working for a reward at short delay, 2) neurons tended to fire more strongly before a short delay, 3) individual neurons firing more strongly before a short delay tended also to fire more strongly before a large reward, and 4) the tendency to fire more strongly before a short delay was far more pronounced in premotor areas caudal to the arcuate sulcus than in association areas rostral to it. The association areas, in contrast, were marked by a tendency for neurons to fire more strongly at the end of the long delay. We conclude that predicting a short delay, like predicting a large reward, induces an enhancement of neuronal activity related to motivational modulation of the monkey's preparatory state.

Animals↗