Changes In Hippocampal Formation Research Articles

PECULIARITIES OF ELECTRON MICROSCOPIC HIPPOCAMPAL FORMATION DEVELOPMENT CHARACTERISTICS IN POSTERITY OF RATS AFTER PGE2 INJECTION FOR LABOR INDUCTION

The aim: To determine the peculiarities of electron microscopic hippocampal formation development characteristics in postetry of rats during two first weeks of postnatal life after intravaginal injection of prostaglandin E2 for labor induction. Materials and methods: The ultrastructural changes of hippocampal formation in posterity of white syngenic rats at the 1st, 7th and 14th days of postnatal life were examined. In this study we used electron-microscopic method. Brain tissue from experimental animals underwent standart stages necessary for electron microscopy and poured into pure Epon. Epon polymerization was carried out in two stages at 36 ° C (12 h) and 56 ° C (24 h). Ultrathin (50-60 nm) sections were obtained on a PowerTome RMC Boeckeler ultratome and then contrasted according to the E. Reynolds method. Ultrathin sections were studied in a PEM-100 electron microscope with an accelerating voltage 60 kV. Results: Based on the obtained data in the study of the hippocampal formation in postery of rats after induction of labor, analysis of the literature devoted to the electron microscopic study of the brain after ischemic injuries, it can be concluded that on the background of stimulation of labor by PgE2, changes corresponding to ischemic damage take place in the rat brain. Conclusions: In posterity of rats after receiving PgE2 for labour induction it was revealed microcirculatory changes; edema of the presynaptic endings, synaptic vesicles aggregation in the center of the presynaptic processes, swelling and destruction of mitochondria; oligodendroglia changes; ultrastructural changes in neurons like edema and vacuolization of mitochondria.

Effects of chrysophanol on hippocampal damage and mitochondrial autophagy in mice with cerebral ischemia reperfusion

Objective The cerebral ischemia-reperfusion (I/R) model is crucial for the study of cerebral stroke. Chrysophanol (Chry) can protect nerve damage of mice in cerebral ischemia-reperfusion injury. This study aimed at investigating the neuroprotective effects of chrysophanol through mitochondrial autophagy in mice with ischemia-reperfusion injury. Materials and methods Adult mice were stochastically divided into five groups: sham, I/R (solvent), I/R+Chry (dose, 10.0ml/kg), I/R+Chry (dose, 1.0ml/kg), and I/R+Chry (dose, 0.1ml/kg). The cerebral ischemia-reperfusion model was made in I/R and I/R+Chry groups. The changes in hippocampal formation were observed by hematoxylin and eosin (H&E) staining. The expressions of LC3B-II and LC3B-I protein in hippocampus were demonstrated by western blot (WB). The fluorescence intensities of NIX, LC3B, and mitochondria were detected by immunohistochemistry fluorescent (IF). Results Comparing with the I/R group, the I/R+Chry groups showed improvements in reducing the damage on the hippocampus, indicated by the reduced ratio of LC3B-II and LC3B-I protein, decreased fluorescence intensity of NIX and LC3B, and increased intensity of mitochondrial fluorescence. Conclusion Our study showed that chrysophanol may regulate mitochondrial autophagy through NIX protein and alleviate the damage of hippocampus through decreasing the level of mitochondrial autophagy.

Elemental changes of hippocampal formation occurring during postnatal brain development

In this paper the elemental changes of rat hippocampal formation occurring during the postnatal development were examined. Three groups of animals were used in the study. These were naive Wistar rats at the age of 6-, 30- and 60-days and the chosen life periods corresponded to the neonatal period, childhood and early adulthood in humans, respectively.For the topographic and quantitative elemental analysis X-ray fluorescence microscopy was applied and the measurements were done at the FLUO beamline of ANKA. The detailed quantitative and statistical analysis was done for four areas of hippocampal formation, namely sectors 1 and 3 of the Ammon’s horn (CA1 and CA3, respectively), dentate gyrus (DG) and its internal area (hilus of DG, H).The obtained results showed that among the all examined elements (P, S, K, Ca, Fe, Cu, Zn and Se), only the levels of Fe and Zn changed significantly during postnatal development of the hippocampal formation and both the elements were significantly higher in young adults comparing to the rats in neonatal period. The increased Fe areal density was found in all examined hippocampal areas whilst Zn was elevated in CA3, DG and H.In order to follow the dynamics of age-dependent elemental changes, the statistical significance of differences in their accumulation between subsequent moments of time was examined. The obtained results showed statistically relevant increase of Zn level only in the first observation period (between 6th and 30th day of life). Afterwards the areal density of the element did not change significantly. The increase of Fe areal density took place in both examined periods, however the observed changes were small and usually not statistically relevant.

Various ketogenic diets can differently support brain resistance against experimentally evoked seizures and seizure-induced elemental anomalies of hippocampal formation

In this paper the influence of two different ketogenic diets (KDs) on the seizure-evoked elemental anomalies of hippocampal formation was examined. To achieve this purpose normal and pilocarpine treated rats previously fed with one of the two high fat and carbohydrate restricted diets were compared with animals on standard laboratory diet. The ketogenic ratios of the examined KDs were equal to 5:1 (KD1) and 9:1 (KD2).KD1 and standard diet fed animals presented similar patterns of seizure-evoked elemental changes in hippocampal formation. Also the analysis of behavioral data recorded after pilocarpine injection did not show any significant differences in intensity and duration of seizures between KD1 and standard diet fed animals.Higher ketogenic ratio KD2 introduced in the normal hippocampal formation prolonged changes in the accumulation of P, K, Zn and Ca. Despite this, both the intensity and duration of seizures were significantly reduced in rats fed with KD2 which suggests that its saving action on the nerve tissue may protect brain from seizure propagation. Also seizure-evoked elemental anomalies in KD2 animals were different than those observed for rats both on KD1 and standard diets. The comparison of seizure experiencing and normal rats on KD2, did not show any statistically significant differences in elemental composition of CA1 and H hippocampal areas whilst in CA3 area only Zn level changed as a result of seizures. DG was the area mostly affected by seizures in KD2 fed rats but areal densities of all examined elements increased in this hippocampal region.

The biochemical changes in hippocampal formation occurring in normal and seizure experiencing rats as a result of a ketogenic diet.

In this study, ketogenic diet-induced biochemical changes occurring in normal and epileptic hippocampal formations were compared. Four groups of rats were analyzed, namely seizure experiencing animals and normal rats previously fed with ketogenic (KSE and K groups respectively) or standard laboratory diet (NSE and N groups respectively). Synchrotron radiation based Fourier-transform infrared microspectroscopy was used for the analysis of distributions of the main organic components (proteins, lipids, compounds containing phosphate group(s)) and their structural modifications as well as anomalies in creatine accumulation with micrometer spatial resolution. Infrared spectra recorded in the molecular layers of the dentate gyrus (DG) areas of normal rats on a ketogenic diet (K) presented increased intensity of the 1740 cm(-1) absorption band. This originates from the stretching vibrations of carbonyl groups and probably reflects increased accumulation of ketone bodies occurring in animals on a high fat diet compared to those fed with a standard laboratory diet (N). The comparison of K and N groups showed, moreover, elevated ratios of absorbance at 1634 and 1658 cm(-1) for DG internal layers and increased accumulation of creatine deposits in sector 3 of the Ammon's horn (CA3) hippocampal area of ketogenic diet fed rats. In multiform and internal layers of CA3, seizure experiencing animals on ketogenic diet (KSE) presented a lower ratio of absorbance at 1634 and 1658 cm(-1) compared to rats on standard laboratory diet (NSE). Moreover, in some of the examined cellular layers, the increased intensity of the 2924 cm(-1) lipid band as well as the massifs of 2800-3000 cm(-1) and 1360-1480 cm(-1), was found in KSE compared to NSE animals. The intensity of the 1740 cm(-1) band was diminished in DG molecular layers of KSE rats. The ketogenic diet did not modify the seizure induced anomalies in the unsaturation level of lipids or the number of creatine deposits.

Hippocampal multimodal structural changes and subclinical depression in healthy individuals

BackgroundSeveral neuroimaging studies report reduced hippocampal volume in depressed patients. However, it is still unclear if hippocampal changes in healthy individuals can be considered a risk factor for progression to clinical depression. Here, we investigated subclinical depression and its hippocampal correlates in a non-clinical sample of healthy individuals, with particular regard to gender differences. MethodsOne-hundred-two participants underwent a comprehensive clinical assessment, a high-resolution T1-weighted magnetic resonance imaging and diffusion tensor imaging protocol using a 3T MRI scanner. Data of macro-(volume) and micro-(mean diffusivity, MD) structural changes of the hippocampus were analyzed with reference to the Beck Depression Inventory score. ResultsResults of multivariate regression analyses revealed reduced bilateral volume, along with increased bilateral MD in hippocampal formation predicting subclinical depressive phenomenology only in healthy males. Conversely, subclinical depressive phenomenology in healthy female was accounted for by only lower educational level, in the absence of any hippocampal structure variations. LimitationsTo date, this is the only evidence reporting a relationship between subclinical depressive phenomenology and changes in hippocampal formation in healthy individuals. ConclusionsOur findings demonstrated that reduced volume, along with increased MD in hippocampal formation, is significantly associated with subclinical depressive phenomenology in healthy males. This encourages to study the hypothesis that early macro- and microstructural changes in hippocampi associated with subclinical depression may constitute a risk factor of developing depressive disorders in males.

Time–place learning is altered by perinatal low-protein malnutrition in the adult rat

Malnutrition produces changes in the central nervous system (CNS) of mammals during development, related to the intensity and timing of the malnutrition insult during the pre- or postnatal period. Protein malnutrition produces irreversible changes in hippocampal formation and some brain stem nuclei. The suprachiasmatic nucleus (SCN) is dramatically altered by low-protein diets during the gestational and perinatal periods. Also, it is known that circadian oscillators regulate physiological, behavioral, and cognitive processes and there is evidence that the time–place learning process exhibits a daily temporal distribution. The aim of this study was to determine the effects of chronic, prenatal, or postnatal malnutrition on daily patterns of the time–place learning process in the adult rat. Forty Sprague–Dawley male 90-day-old rats, were divided into four groups: 10 well nourished controls (Co), 10 chronically (CM), 10 prenatally malnourished (PrM), and 10 postnatally malnourished (PtM) rats. Efficiency in time–place learning was tested by using a behavioral T-maze. Each rat was assayed for 10 trials before considering the final probe of efficiency. Each trial was 60 seconds long, final efficiency was measured by the amount of time the rat took to reach the end of an arm containing a water pot. Each rat was tested in 2-hour spans until completion of a full 24-hour cycle. A Cosinor analysis was used to evaluate acrophase and percentage of rhythmicity. The obtained results suggest that time-place learning process is influenced by the circadian clock. The severity and timing of prenatal or chronic protein malnutrition modifies the acrophase and rhythmicity of the learning circadian pattern, which can impact important cognitive functions.

Physical exercise during the adolescent period of life increases hippocampal parvalbumin expression

In order to investigate whether physical exercise during development would promote changes the calcium-binding protein parvalbumin (PV) expression in the hippocampal formation, we performed an immunostaining study after an aerobic exercise program in rats during adolescent period of life. Wistar rats were submitted to daily exercise program in a treadmill between postnatal day 21 and 60. Running time and speed were gradually increased during the subsequent days until 18 m/min for 60 min. After the aerobic exercise program, animals of all groups were killed and PV immunostaining procedures were performed. The results showed significant increase of protein level in the hippocampal formation and PV-immunoreactive neurons in CA1 and CA2/CA3 regions of rats submitted to exercise when compared with control rats. This finding indicates that aerobic exercise program during adolescent period promotes neuroplastic changes in hippocampal formation.

Neuropathological quantification of dtg APP/PS1: neuroimaging, stereology, and biochemistry

Murine models that mimic the neuropathology of Alzheimer's disease (AD) have the potential to provide insight into the pathogenesis of the disease and lead to new strategies for the therapeutic management of afflicted patients. We used magnetic resonance imaging (MRI), design-based stereology, and high performance liquid chromatography (HPLC) to assess the age-related neuropathology in double transgenic mice that overexpress two AD-related proteins--amyloid precursor protein (APP) and presenilin 1 (PS1)--and age- and gender-matched wild-type (WT) controls. In mice ranging in age from 4-28 months, total volumes of the hippocampal formation (V (HF)) and whole brain (V (brain)) were quantified by the Cavalieri-point counting method on a systematic-random sample of coronal T2-weighted MRI images; the same stereological methods were used to quantify V (HF) and V (brain) after perfusion and histological processing. To assess changes in AD-type beta-amyloid (A beta) plaques, sections from the hippocampal formation and amylgdaloid complex of mice aged 5, 12, and 15 months were stained by Congo Red histochemistry. In aged mice with large numbers of amyloid plaques, systematic-random samples of sections were stained by GFAP immunocytochemistry to assess gender and genotype effects on total numbers of astrocytes. In addition, levels of norepinephrine (NE), dopamine (DA), serotonin (5-HT) and 5-HT metabolites were assayed by HPLC in fresh-frozen samples from neocortex, striatum, hippocampus, and brainstem. We confirmed age-related increases in amyloid plaques, beginning with a few plaques at 5 months of age and increasing densities by 12 and 15 months. At 15 months of age, there were robust genotype effects, but no gender effects, on GFAP-immunopositive astrocytes in the amygdaloid complex and hippocampus. There were no effects on monoamine levels in all brain regions examined, and no volume changes in hippocampal formation or whole brain as quantified on either neuroimages or tissue sections. Strong correlations were present between volume estimates from MRI images and histological sections, with about 85% reduction in mean V (HF) or mean V (brain) between MRI and processed histological sections. In summary, these findings show that the double transgenic expression of AD-type mutations is associated with age-related increases in amyloid plaques and astrocytosis; however, this model does not recapitulate the cortical atrophy or neurochemical changes that are characteristic of AD.

Effects of different types of physical exercise on the staining of parvalbumin-positive neurons in the hippocampal formation of rats with epilepsy

Effects of exercise in animals with epilepsy have been demonstrated. To investigate whether the type of physical activity, voluntary or forced, would promote different morphological changes in hippocampal formation we performed an immunocytochemical study using the parvalbumin (PV) distribution as a marker. Control rats and rats with epilepsy were submitted to a voluntary (wheel running) and forced (treadmill) exercise for 10 days (acute physical exercise) or 45 days (chronic physical exercise). It was observed in normal rats a higher number of PV-positive cells in the hilus of dentate gyrus (DG) in the voluntary and forced exercise groups (acute and chronic physical exercise), when compared to the control group. In animals with epilepsy the number of PV-positive cells and staining intensity of PV-fibers in the hilus was significantly higher only in the acute physical exercise (voluntary and forced). These findings demonstrate that acute physical exercise, both voluntary and forced results in increased number of PV-positive cells and staining intensity of PV-fibers in the hilus of rats with epilepsy and the occurrence of these changes takes place only in the early phase of epilepsy.

Neurokognition psychiatrischer Patienten

Cognitive, mnestic, and emotional disturbances can occur in a wide range of psychiatric patients. Both neurochemical alterations as well as structural brain abnormalities can be neural correlates of neuropsychological dysfunctions in these patients. In this paper, we give an introduction to neuropsychological domains with a focus on different kinds of memory and executive functions. Thereafter, we describe neurocognitive deteriorations in patients with schizophrenia, depression, alcohol addiction, and Korsakoff's syndrome. Brain alterations affect primarily parts of the frontal lobe, especially the dorsolateral prefrontal and the orbitofrontal cortex. This can be seen in volume reduction, glucose hypometabolism, or dysfunctions of dopaminergic fronto-striatal loops. Furthermore, structural or functional changes of hippocampal formation, anterior cingulate gyrus, amygdala, and different thalamic nuclei are also involved in neurocognitive disturbances of psychiatric patients.

Differential effects of spontaneous versus forced exercise in rats on the staining of parvalbumin-positive neurons in the hippocampal formation

To investigate whether the type of physical activity, voluntary or forced, would promote different morphological changes in hippocampal formation we performed an immunocytochemical study using the parvalbumin (PV) distribution as a marker. Animals submitted to the voluntary exercise were placed in a voluntary wheel running and those submitted to the forced exercise were placed in a motor driven treadmill. Both exercise groups were submitted to 10 consecutive days of physical activity. It was observed a higher number of PV-positive cells in the hilus of dentate gyrus (DG) in the voluntary and forced exercise groups when compared to the control group. The voluntary exercise group also presented a stronger fiber staining in the DG hilus than the forced exercise and control groups. In contrast, no differences were found in the pattern of PV staining in CA1/CA3 region between exercise and control groups. These findings demonstrate that physical activity leads to prominent plastic changes in the hippocampal formation of rats that were more evident following voluntary activity.