Acute and Chronic Exposure to Linagliptin, a Selective Inhibitor of Dipeptidyl Peptidase-4 (DPP-4), Has an Effect on Dopamine, Serotonin and Noradrenaline Level in the Striatum and Hippocampus of Rats

Linagliptin is a selective dipeptidyl peptidase-4 (DPP-4) inhibitor that indirectly elevates the glucagon-like peptide-1 (GLP-1) level. The aim of the present study was to check whether linagliptin has an influence on neurotransmission in rat brain. Rats were acutely and chronically exposed to linagliptin (10 and 20 mg/kg, intraperitoneally (i.p.)). Twenty-four hours later, the striatum and hippocampus were selected for further studies. In neurochemical experiments, using high-performance liquid chromatography with electrochemical detection (HPLC-ED), the concentrations of three major neurotransmitters-dopamine, serotonin and noradrenaline-and their metabolites were measured. The analysis of mRNA expression of dopamine (D1 and D2), serotonin (5-HT-1 and 5-HT-2) and noradrenaline (α1 and α2a) receptors was also investigated using real-time quantitative reverse transcription polymerase chain reaction (RQ-PCR) in the same brain areas. Linagliptin has the ability to influence the dopaminergic system. In the striatum, the elevation of dopamine and its metabolites was observed after repeated administration of that linagliptin, and in the hippocampus, a reduction in dopamine metabolism was demonstrated. Acute linagliptin exposure increases the serotonin level in both areas, while after chronic linagliptin administration a tendency for the mRNA expression of serotoninergic receptors (5-HT1A and 5-HT2A) to increase was observed. A single instance of exposure to linagliptin significantly modified the noradrenaline level in the striatum and intensified noradrenaline turnover in the hippocampus. The recognition of the interactions in the brain between DPP-4 inhibitors and neurotransmitters and/or receptors is a crucial step for finding novel discoveries in the pharmacology of DPP-4 inhibitors and raises hope for further applications of DPP-4 inhibitors in clinical practices.

Matrix-assisted laser desorption/ionization mass spectrometry imaging sample preparation using wet-interface matrix deposition for lipid analysis

RATIONALE

Sample preparation is one of the most crucial steps for matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). Scientists beginning their study with this technique may be overwhelmed by the variety of matrices, solvents, and concentrations; the methods of their applications; and the lack of widely available knowledge of the effect of these parameters on the results. Here we present in depth the aspects of matrix deposition, which will be helpful for the scientific community.

METHODS

In this study, we tested several MALDI matrices, such as 2,5-dihydroxybenzoic acid (DHB), norharmane, N-(1-naphthyl)ethylenediamine dihydrochloride (NEDC), and 9-aminoacridine (9AA), using the SunCollect system: wet-interface matrix deposition in the context of lipid analysis. We optimized the number of matrix layers and nozzle settings in terms of spectral intensity and the overall quality of the obtained ion maps.

RESULTS

Our research presents the effect of the number of matrix layers and nozzle settings on the results and allows for choosing the optimal parameters for the analyses. In positive ionization mode, DHB matrix could be chosen first. In the negative ionization mode, 1,5-diaminonaphthalene matrix produces a higher peak intensity in a lower mass range and seems to provide more information than 9AA. We recommend NEDC for particular processes such as glucose analysis. Compared to the remaining matrices, norharmane shows significant changes in the obtained ion maps.

CONCLUSIONS

Such a large amount of data allow us to observe an interesting conclusion: the obtained ion image for a particular ion could differ dramatically with a change in the matrix, the solvent composition, or even the number of matrix layers. This must be considered when interpreting the result, impelling us to compare the results obtained with different matrices with caution.

Insight into Glutamatergic Involvement in Rewarding Effects of Mephedrone in Rats: In Vivo and Ex Vivo Study

Mephedrone is a widely used drug of abuse, exerting its effects by interacting with monoamine transporters. Although this mechanism has been widely studied heretofore, little is known about the involvement of glutamatergic transmission in mephedrone effects. In this study, we comprehensively evaluated glutamatergic involvement in rewarding effects of mephedrone using an interdisciplinary approach including (1) behavioural study on effects of memantine (non-selective NMDA antagonist) on expression of mephedrone-induced conditioned place preference (CPP) in rats; (2) evaluation of glutamate concentrations in the hippocampus of rats following 6 days of mephedrone administration, using in vivo magnetic resonance spectroscopy (MRS); and (3) determination of glutamate levels in the hippocampus of rats treated with mephedrone and subjected to MRS, using ion-exchange chromatography. In the presented research, we confirmed priorly reported mephedrone-induced rewarding effects in the CPP paradigm and showed that memantine (5 mg/kg) was able to reverse the expression of this effect. MRS study showed that subchronic mephedrone administration increased glutamate level in the hippocampus when measured in vivo 24 h (5 mg/kg, 10 mg/kg and 20 mg/kg) and 2 weeks (5 mg/kg and 20 mg/kg) after last injection. Ex vivo chromatographic analysis did not show significant changes in hippocampal glutamate concentrations; however, it showed similar results as obtained in the MRS study proving its validity. Taken together, the presented study provides new insight into glutamatergic involvement in rewarding properties of mephedrone.

Dietary supplementation with Lactobacillus rhamnosus JB-1 restores brain neurochemical balance and mitigates the progression of mood disorder in a rat model of chronic unpredictable mild stress

Major depressive disorder is a stress-related disease associated with brain metabolic dysregulation in the glutamine-glutamate/γ-aminobutyric acid (Gln-Glu/GABA) cycle. Recent studies have demonstrated that microbiome-gut-brain interactions have the potential to influence mental health. The hypothesis of this study was that Lactobacillus rhamnosus JB-1 (LR-JB1™) dietary supplementation has a positive impact on neuro-metabolism which can be quantified in vivo using magnetic resonance spectroscopy (MRS). A rat model of depressive-like disorder, chronic unpredictable mild stress (CUMS), was used. Baseline comparisons of MRS and behavior were obtained in a control group and in a stressed group subjected to CUMS. Of the 22 metabolites measured using MRS, stressed rats had significantly lower concentrations of GABA, glutamate, glutamine + glutathione, glutamate + glutamine, total creatine, and total N-acetylaspartate (tNAA). Stressed rats were then separated into 2 groups and supplemented with either LR-JB1™ or placebo and re-evaluated after 4 weeks of continued CUMS. The LR-JB1™ microbiotic diet restored these metabolites to levels previously observed in controls, while the placebo diet resulted in further significant decrease of glutamate, total choline, and tNAA. LR-JB1™ treated animals also exhibited calmer and more relaxed behavior, as compared with placebo treated animals. In summary, significant cerebral biochemical downregulation of major brain metabolites following prolonged stress were measured in vivo using MRS, and these decreases were reversed using a microbiotic dietary supplement of LR-JB1™, even in the presence of continued stress, which also resulted in a reduction of stress-induced behavior in a rat model of depressive-like disorder.

[First-hand experiences in trans-sylvian microsurgery of the posterior part of the circulus arteriosus and end-part of the basilar artery]

The authors present the technique and the obtained results of surgical treatment of vascular malformations in the upper part of the basilar artery in 14 patients using a trans-sylvian microsurgical approach. The techniques of subfrontal and subtemporal approaches are compared.

[A case of spinal cord angioma with selective damage of the peripheral motor neurons]

A 47-year-old man is reported who had an extensive arteriovenous angioma of the spinal cord confirmed during operation. The patient had an atypical symptom complex, with clinically evident deep flaccid paresis of lower extremities without pyramidal signs, sensory disturbances and sphincter disturbances. The anomaly causing a steal mechanism led to ischaemia of the anterior horns of the cord.

[Analysis of the effects of various methods of classical exclusion of anterior cerebral artery aneurysms on late structural and functional changes in relation to the various approaches]

The effects were analysed of various techniques of classical exclusion of aneurysms in the anterior cerebral artery system on the late therapeutic result and on the development of ischaemic lesions in the area of approach to the aneurysm. The approaches used were: interhemispheric, fronto-temporal and fronto-temporo-sphenoidal, and the aneurysms were excluded with a ligature or metal clip. The best method of approach was chosen after analysis of late results of neurological, psychological and CT studies. It was demonstrated that pressure of a spatula during the operation may produce permanent ischaemic changes at the site of the pressure which may lead to persistence of psychic disturbances late after the operation. It was shown also that the most favourable classic technique of operation in cases of aneurysms in this portion is the fronto-temporo-sphenoidal approach with use of a metal clip.

[Evaluation of the efficiency of intracranial volume compensation before and after surgical treatment of intracranial hematoma]

On the ground of the clinical status and indicators of intracranial pressure instability and cerebral arterial reactivity the authors evaluated the efficiency of intracranial volume compensatory mechanisms in 21 patients before and after operations for epidural and subdural haematomas and spontaneous intracerebral haematomas. The epidural haematomas in a greater degree but less permanently exhausted the efficiency of the compensatory mechanisms than subdural haematomas and after their removal these mechanisms regained easier their efficiency than after removal of subdural haematomas. In cases of spontaneous intracerebral haematomas the efficiency of the compensatory mechanisms is only slightly decreased.

[Effect of cerebral angiography on intracranial pressure in dogs]

Intracranial pressure changes in dogs after intra-arterial administration of contrast media and saline in different amounts at various flow rates were studied by the authors, using continuous epidural pressure recording. In two animals the venous pressure was measured as well. Contrast media and saline alike were found to produce similar intracranial pressure increases when given intravenously though a greater rise with longer-lasting fall and successive rise of the pressure was observed when the former were used. The increase of the amount of the medium or saline had no significant effect on the value of ultracranial pressure.

[Epidemiology of fronto-basilar head injuries]

Fractures of the cranial basis in the anterior cranial fossa accounted in a ten-year period in the material of the authors for 2.6% of cranial traumas and 24.6% of cranial basis fractures. In the observed cases rhinorrhoea was present in only 16% of cases. Purulent meningitis as a complication was observed in only 1.8% of cases and only late after the trauma. In view of the low frequency of inflammatory complications evidencing a considerable tendency for spontaneous healing of fistulas the authors suggest restriction of indications to surgical treatment in early period after trauma to cases with visible wide fissure in the fractures bone, displacement of fractured fragments and their position at different levels.

[Our evaluation of clinical usefulness of continuous extradural measurement of intracranial pressure in patients with cranio-cerebral injuries]

Continuous measurements of intracranial, pressure were conducted by the extradural method in 40 patients with various types of skull trauma. A correlation was demonstrated between the value of this pressure and the clinical condition of the patient only with high values of the pressure, in which nearly always wave-like pressure changes were observed. The occurrence of wave-like changes was a more reliable sign of threatening cranial hypertension than the value of intracranial pressure. Continuous measurement of pressure during intravenous administration of glycerol demonstrated that a significant fall of pressure preceded the regression of clinical signs of intracranial hypertension.

[Intracranial pressure instability index as a new method of evaluating the capacity of intracranial volume compensation]

An index of intracranial pressure instability is calculated as a new way to evaluate the capacity of intracranial voluminal compensation in patients suffering from cranio-cerebral trauma. The value of the index is determined by mutual relations of intracranial pressure standard deviations measured during 3-minute periods before and after intracranial administration of 2 ml of 0.9% NaCl. Normal physiological range of the index was evaluated in controls without intracranial pathology.

[Case of paranasal sinus osteoma with cerebrospinal rhinorrhea and pneumocephalus]

The authors describe a case of osteoma of the paranasal sinuses growing into the anterior cranial fossa with liquorrhoea and aerocele treated successfully surgically from an osteoplastic transsinusal approach.

[Case of intracranial chondroma]

The authors present a case of intaracranial chondrome originating from the pia mater and discuss the development of intracranial chondromas and role of cranial trauma in it.

[Unusual clinical course in a case of carcinomatosis of cerebrospinal meninges]

The authors report the clinical course of a case of carcinomatosis of the cerebrospinal meninges with frequent sudden rises of intracranial pressure and with lethal outcome. The primary tumour was a mucinous carcinoma of the ovary. In treatment Pudenz valve was used successfully for connecting the subarachnoid space of the spinal cord with the peritoneal cavity. This shunting of the cerebrospinal fluid caused no dissemination of the neoplasm within the peritoneal cavity.