Effects of immunosuppressants FK506 and cyclosporin A on the developing rat brain

Tacrolimus (FK506) and cyclosporin A (CsA) are immunosuppressants commonly used in transplantology. Their neuroprotective actions have also frequently been reported. Unfortunately, after prolonged administration, the drugs have numerous negative neurological side-effects which could also be observed in paediatric clinical cases. Since the problem has never been explored experimentally, the present study focuses on FK506 and CsA influence on the developing rat brain. Six- and 30-day-old rats (P6s and P30s, respectively) received two injections of FK506 or CsA, at a 24-hr interval. Control rats were injected with vehicle alone (Cremophor and ethanol mixture). When the rats were 60-day-old, weights and sizes of their brains were recorded. Additionally, quantitative assessment of calretinin-(CR+) and parvalbumin-immunopositive (PV+) inhibitory neurons was performed. In comparison to naive or vehicle-injected controls, FK506 or CsA-treated P6s showed decreases in the brain weight. In P30s, a decrease in the brain weight was observed only following the vehicle injections. In P6s, CsA injections reduced both CR+ and PV+ neuronal populations while FK506 injections reduced only numbers of PV+ neurons. In P30s, injections of the vehicle alone, but not those of FK506 or CsA, led to significant reductions of the CR+ and PV+ neurons. Generally, the results suggest negative long-term effects of FK506 or CsA on the developing brain. Interestingly, the negative effects of the vehicle were much stronger

Interleukin-1\beta affects the macrophage recruitment and proliferation in the injured brain of 6-day-old rat

Six-day-old male rats received a mechanical lesion in the left cerebral hemisphere. Thereafter, a single dose of either 5, 50 or 500 units (U) of recombinant rat interleukin-1 beta (IL-1 beta) was injected into the lesion cavity. One or 2 days after the injury, the rats were injected with H-3-thymidine. Brain sections were subjected to BSI-B4 lectin histochemistry and autoradiography to visualise proliferating and non-proliferating macrophages located within the region of injury. A mitogenic effect of IL-1 beta on macrophages was observed on day 2 in brains injected with the lowest 5 U dose of cytokine. Following administration of higher 50 U and 500 U doses, infiltration of the injured tissue by macrophages was significantly intensified on day 1. However, on day 2, dose-dependent reductions of the total number of macrophages as well as their proliferative activity were recorded. The findings suggest that the higher the initial quantity of macrophages,the sooner they disappeared from the injury site. It may therefore be hypothesised that IL-1 beta-induced increase in macrophage recruitment at the beginning of the inflammatory response speeded the removal of tissue debris and, therefore, accelerated healing of the injured nervous tissue

The use of SR-FTIR microspectroscopy for a preliminary biochemical study of the rat hippocampal formation tissue in case of pilocarpine induced epilepsy and neutroprotection with FK-506

The main aim of the work was the biochemical analysis of the hippocampal formation tissue in the case of epileptic rats treated with the neuroprotective agent FK-506. Three groups of animals were compared: rats with pilocarpine induced seizures treated and non-treated with tacrolimus as well as naive controls. Synchrotron radiation Fourier transform infrared (SR-FTIR) microspectroscopy was used for the biomolecular analysis of studied samples. The measurements were carried out at SISSI beamline of ELETTRA. A Bruker IFS 66v/S interferometer coupled to a Bruker Hyperion 2000 microscope was used. The tissue samples were analyzed in transmission mode with a beam defined by a small aperture and spatial resolution steps of 10 mu m which allowed us to probe the selected cross-line of the sample at cellular resolution. The obtained results enabled to compare the distributions of proteins and lipids in the three hippocampal cellular layers, i.e. in molecular, multiform and granular layers. For epileptic animals both treated and non-treated with FK-506, the tendency for increase of the ratio of the absorbance at around 1548 and 1658 cm(-1) (amide II/amide I ratio) was observed, however only for the multiform layer these changes were statistically significant. Similar relation was noticed in case of the ratio of the absorbance at around 1631 and 1658 cm(-1). The mentioned results may suggest conformational changes of proteins in the direction of beta-sheet secondary structure. Additionally, a statistically significant increase in the lipid massif and a decrease of the ratio of absorbance at around 2921 and 2958 cm(-1) were observed for epileptic animals treated with tacrolimus comparing to the control group

Elemental changes in the hippocampal formation following two different formulas of ketogenic diet : an X-ray fluorescence microscopy study

The main purpose of the following study was the determination of elemental changes occurring within hippocampal formation as a result of high-fat and carbohydrate-restricted ketogenic diet (KD). To realize it, X-ray fluorescence microscopy was applied for topographic and quantitative analysis of P, S, K, Ca, Fe, Cu, Zn and Se in hippocampal formations taken from rats fed with two different KDs and naive controls. The detailed comparisons were done for sectors 1 and 3 of the Ammon’s, the dentate gyrus and hilus of dentate gyrus. The results of elemental analysis showed that the KDs induced statistically significant changes in the accumulation of P, K, Ca, Zn and Se in particular areas of hippocampal formation and these alterations strongly depended on the composition of the diets. Much greater influence on the hippocampal areal densities of examined elements was found for the KD which was characterized by a lower content of carbohydrates, higher content of fats and increased proportion of unsaturated fatty acids. The levels of P, K and Zn decreased whilst those of Ca and Se increased as a result of the treatment with the KDs

Elemental anomalies in the hippocampal formation after repetitive electrical stimulation : an X-ray fluorescence microscopy study

Our previous studies carried out on the pilocarpine model of seizures showed that highly resolved elemental analysis might be very helpful in the investigation of processes involved in the pathogenesis of epilepsy, such as excitotoxicity or mossy fiber sprouting. In this study, the changes in elemental composition that occurred in the hippocampal formation in the electrical kindling model of seizures were examined to determine the mechanisms responsible for the phenomenon of kindling and spontaneous seizure activity that may occur in this animal model. X-ray fluorescence microscopy was applied for topographic and quantitative analysis of selected elements in tissues taken from rats subjected to repetitive transauricular electroshocks (ES) and controls (N). The detailed comparisons were carried out for sectors 1 and 3 of the Ammon's horn (CA1 and CA3, respectively), the dentate gyrus (DG) and hilus of DG. The obtained results showed only one statistically significant difference between ES and N groups, namely a higher level of Fe was noticed in CA3 region in the kindled animals. However, further analysis of correlations between the elemental levels and quantitative parameters describing electroshock-induced tonic and clonic seizures showed that the areal densities of some elements (Ca, Cu, Zn) strongly depended on the progress of kindling process. The areal density of Cu in CA1 decreased with the cumulative (totaled over 21 stimulation days) intensity and duration of electroshock-induced tonic seizures while Zn level in the hilus of DG was positively correlated with the duration and intensity of both tonic and clonic seizures

Does long-term high fat diet always lead to smaller hippocampi volumes, metabolite concentrations, and worse learning and memory? : a magnetic resonance and behavioral study in wistar rats

Background. Obesity is a worldwide epidemic with more than 600 million affected individuals. Human studies have demonstrated some alterations in brains of otherwise healthy obese individuals and elevated risk of neurodegenerative disease of old age; these studies have also pointed to slightly diminished memory and executive functions among healthy obese individuals. Similar findings were obtained in animal models of obesity induced by high fat diet. On the other hand, low carbohydrate high fat diets are currently promoted for losing weight (e.g., Atkin’s style diets). However, the long-term effects of such diets are not known. Additionally, high fat diets leading to (mild) ketonemia were shown to improve brain function in elderly humans and in some animal models. Aim. To evaluate the hypothesis that long-term use of a high fat diet was associated with decreases in spatial memory, smaller hippocampi and hippocampi metabolite concentrations in Wistar rats. Methods. Twenty five male Wistar rats were put on high fat diet (HFD; 60% calories from fat, 30% from carbohydrates) on their 55th day of life, while 25 control male rats (CONs) remained on chow. Adequate levels of essential nutrients were provided. Both groups underwent memory tests in 8-arm radial maze at 3rd, 6th, 9th, and 12th month. 1H magnetic resonance spectroscopy was employed to measure concentrations of tNAA (marker of neuronal integrity) at one month and one year, whereas MRI was used to evaluate hippocampal volumes. Results. Obese rats (OBRs) consumed similar amount of calories as CONs, but less proteins. However, their protein intake was within recommended amounts. Throughout the experiment OBRs had statistically higher concentrations of blood ketone bodies than CONs, but still within normal values. At post-mortem assessment, OBRs had 38% larger fat deposits than CONs (p<0.05), as evaluated by volume of epididymis fat, an acknowledged marker of fat deposits in rats. Contrary to our expectations, OBRs had better scores of memory behavioral tasks than CONs throughout the experiment. At one year, their hippocampi were by 2.6% larger than in CONs (p = 0.05), whereas concentration of tNAA was 9.8% higher (p = 0.014). Conclusion. Long-term HFD in our study resulted in better memory, larger hippocampal volumes, as well as higher hippocampal metabolite concentrations, possibly due to increased levels of blood ketone bodies. The results should be interpreted with caution, as results from animal models do not necessarily directly translate in human condition

Altered Elemental Distribution in Male Rat Brain Tissue as a Predictor of Glioblastoma Multiforme Growth : Studies Using SR-XRF Microscopy

Glioblastoma multiforme (GBM) is a particularly malignant primary brain tumor. Despite enormous advances in the surgical treatment of cancer, radio- and chemotherapy, the average survival of patients suffering from this cancer does not usually exceed several months. For obvious ethical reasons, the search and testing of the new drugs and therapies of GBM cannot be carried out on humans, and for this purpose, animal models of the disease are most often used. However, to assess the efficacy and safety of the therapy basing on these models, a deep knowledge of the pathological changes associated with tumor development in the animal brain is necessary. Therefore, as part of our study, the synchrotron radiation-based X-ray fluorescence microscopy was applied for multi-elemental micro-imaging of the rat brain in which glioblastoma develops. Elemental changes occurring in animals after the implantation of two human glioma cell lines as well as the cells taken directly from a patient suffering from GBM were compared. Both the extent and intensity of elemental changes strongly correlated with the regions of glioma growth. The obtained results showed that the observation of elemental anomalies accompanying tumor development within an animal’s brain might facilitate our understanding of the pathogenesis and progress of GBM and also determine potential biomarkers of its extension. The tumors appearing in a rat’s brain were characterized by an increased accumulation of Fe and Se, whilst the tissue directly surrounding the tumor presented a higher accumulation of Cu. Furthermore, the results of the study allow us to consider Se as a potential elemental marker of GBM progression