Increase In Cerebrospinal Fluid Concentrations Research Articles

Enhanced Delivery of Lopinavir to the Cns Using Compritol ® -Based Solid Lipid Nanoparticles

Protease inhibitors such as lopinavir have negligible permeability to the CNS due to blood-brain and blood-cerebrospinal fluid interfaces. An attempt has been made to develop solid lipid nanoparticles to increase the availability of lopinavir in the CNS. Solid lipid nanoparticle formulations exhibited a Cmax and T(max) of 632.86 +/- 81.61 ng/ml and 25 +/- 7.75 min, respectively, with a significant increase in bioavailability in a rat model compared with a free-drug suspension. An appreciable increase in cerebrospinal fluid concentration was detected with solid lipid nanoparticle formulations. Compritol-based solid lipid nanoparticles with a poloxamer coating can be effectively absorbed through the lymphatic system, prolong the circulation of drug in blood by acting as a reservoir and can effectively target the drug to the CNS due to the combined effect of lipophilicity and surface charge. The high biocompatibility, biodegradability and nontoxicity of compritol make the compritol-based solid lipid nanoparticles an excellent carrier for enhanced CNS delivery of lopinavir.

Blood–brain‐barrier disruption in chronic canine hypothyroidism

Central nervous system (CNS) manifestations of hypothyroidism have been associated with cerebrovascular complications. Reports of cerebrospinal fluid (CSF) abnormalities are rare in hypothyroid dogs. The aim of this study was to determine if chronic hypothyroidism causes blood-brain-barrier (BBB) abnormalities that are detectable using indirect CSF biomarkers. The study included 18 normal, euthyroid, female mixed-breed dogs. Hypothyroidism was induced by (131) iodine administration in 9 dogs; 9 served as untreated controls. Evaluations included physical and neurologic examination, complete CSF analysis, serum and CSF protein electrophoresis, measurement of plasma vascular endothelial growth factor (VEGF) and serum S-100B concentrations, and calculation of CSF albumin quota (AQ) and were conducted at baseline and 6, 12, and 18 months after induction of hypothyroidism. Data were analyzed using repeated measures ANOVA. At baseline, differences between groups were not detected for any variable. Throughout the study, controls dogs remained free of neurologic disease and had test variables that remained within reference intervals. Two hypothyroid dogs developed CNS signs during the study, and evidence of cerebrovascular disease was found at necropsy. At 12 and 18 months, the CSF total protein, VEGF, S-100B, and fractional albumin concentrations, and AQ were significantly higher (P<.04) in hypothyroid dogs than controls. Among test variables assayed in serum or plasma, the only significant difference was a higher S-100B concentration in hypothyroid dogs (P=.003) at 18 months. BBB integrity is disrupted in chronic hypothyroidism. Significant increases in CSF concentrations of VEGF and S100-B in hypothyroid dogs indicate dysfunction in both endothelial and glial elements of the BBB.

Neuropeptide changes and neuroactive amino acids in CSF from humans and sheep with neuronal ceroid lipofuscinoses (NCLs, Batten disease)

Anomalies in neuropeptides and neuroactive amino acids have been postulated to play a role in neurodegeneration in a variety of diseases including the inherited neuronal ceroid lipofuscinoses (NCLs, Batten disease). These are often indicated by concentration changes in cerebrospinal fluid (CSF). Here we compare CSF neuropeptide concentrations in patients with the classical juvenile CLN3 form of NCL and the classical late infantile CLN2 form with neuropeptide and neuroactive amino acid concentrations in CSF from sheep with the late infantile variant CLN6 form. A marked disease related increase in CSF concentrations of neuron specific enolase and tau protein was noted in the juvenile CLN3 patients but this was not observed in an advanced CLN2 patient nor CLN6 affected sheep. No changes were noted in S-100b, GFAP or MBP in patients or of S-100b, GFAP or IGF-1 in affected sheep. There were no disease related changes in CSF concentrations of the neuroactive amino acids, aspartate, glutamate, serine, glutamine, glycine, taurine and GABA in these sheep. The changes observed in the CLN3 patients may be progressive markers of neurodegeneration, or of underlying metabolic changes perhaps associated with CLN3 specific changes in neuroactive amino acids, as have been postulated. The lack of changes in the CLN2 and CLN6 subjects indicate that these changes are not shared by the CLN2 or CLN6 forms and changes in CSF concentrations of these compounds are unreliable as biomarkers of neurodegeneration in the NCLs in general.

Increases in Cerebrospinal Fluid Caffeine Concentration are Associated with Favorable Outcome after Severe Traumatic Brain injury in Humans

Caffeine, the most widely consumed psychoactive drug and a weak adenosine receptor antagonist, can be neuroprotective or neurotoxic depending on the experimental model or neurologic disorder. However, its contribution to pathophysiology and outcome in traumatic brain injury (TBI) in humans is undefined. We assessed serial cerebrospinal fluid (CSF) concentrations of caffeine and its metabolites (theobromine, paraxanthine, and theophylline) by high-pressure liquid chromatography/ultraviolet in 97 ventricular CSF samples from an established bank, from 30 adults with severe TBI. We prospectively selected a threshold caffeine level of > or = 1 micromol/L (194 ng/mL) as clinically significant. Demographics, Glasgow Coma Scale (GCS) score, admission blood alcohol level, and 6-month dichotomized Glasgow Outcome Scale (GOS) score were assessed. Mean time from injury to initial CSF sampling was 10.77+/-3.13 h. On initial sampling, caffeine was detected in 24 of 30 patients, and the threshold was achieved in 9 patients. Favorable GOS was seen more often in patients with CSF caffeine concentration > or = versus < the threshold (55.6 versus 11.8%, P=0.028). Gender, age, admission CGS score, admission blood alcohol level, and admission systolic arterial blood pressure did not differ between patients with CSF caffeine concentration > or = versus < the threshold. Increases in CSF concentrations of the caffeine metabolites theobromine and paraxanthine were also associated with favorable outcome (P=0.018 and 0.056, respectively). Caffeine and its metabolites are commonly detected in CSF in patients with severe TBI and in an exploratory assessment are associated with favorable outcome. We speculate that caffeine may be neuroprotective by long-term upregulation of adenosine A1 receptors or acute inhibition of A2a receptors.

S100B LEVELS IN THE CEREBROSPINAL FLUID OF RATS ARE SEX AND ANAESTHETIC DEPENDENT

1. S100B is a calcium-binding protein that acts as a neurotrophic cytokine and is expressed in the central nervous system, predominantly by astrocytes. At nanomolar concentrations, S100B stimulates neurite outgrowth and glial glutamate uptake, as well as protecting neurons against glutamate excitoxicity. 2. Peripheral S100B concentrations, particularly in the serum and cerebrospinal fluid (CSF), have been used as a parameter of glial activation or death in several physiological and pathological conditions. 3. In the present study, we investigated the effect of anaesthetics (thiopental, ketamine and halothane) on CSF concentrations of S100B, as well as a possible sex dependence, because several studies have suggested astrocytes as putative targets for oestrogen. 4. Higher levels of CSF S100B were found when rats were anaesthetized with thiopental; these levels, independently of anaesthetic, were sex dependent. Conversely, no effect of anaesthetic or sex was observed on serum concentrations of S100B. 5. The increase in CSF concentrations of S100B induced by thiopental was confirmed in non-anaesthetized neonatal rats and cortical astrocyte cultures. 6. Assuming CSF S100B as a marker of development, glial activation or even brain damage, investigations regarding the sex dependence of its concentration may be useful in gaining an understanding of sex variations in the behaviour and the pathological course of, as well as susceptibility to, many brain disorders. The findings of the present study reinforce the sex effect on synaptic plasticity and suggest a sex dependence of neural communication mediated by extracellular S100B without restricting the influence of astrocytes on the developmental phase.

Cyclosporine-A-mediated inhibition of p-glycoprotein increases methylprednisolone entry into the central nervous system

Prospective, randomized, pharmacokinetic study. To determine if cyclosporine-A-mediated inhibition of p-glycoprotein would increase methylprednisolone entry into the central nervous system thereby permitting a reduction in the systemic methylprednisolone dose. Department of Anesthesiology, University of Washington, Seattle, USA. Microdialysis probes were used to obtain cerebrospinal fluid and gluteal muscle extracellular fluid samples for measurement of methylprednisolone concentration in pigs. At time zero, a methylprednisolone bolus was given and an infusion started. At 210 min, after reaching a stable methylprednisolone concentration, a cyclosporine-A bolus was given (either 10 or 30 mg/kg) and microdialysis samples collected until 420 min. Plasma samples were collected at 10, 30 min and then every 30 min until the study's end. Cyclosporine-A bolus produced a dose-dependant increase in methylprednisolone concentration in plasma, muscle and cerebrospinal fluid. Importantly, the magnitude of the increase in cerebrospinal fluid was significantly greater than the increase in plasma and muscle. The relatively greater increase in cerebrospinal fluid concentrations of methylprednisolone is consistent with increased penetration of the blood-brain barrier secondary to cyclosporine-mediated p-glycoprotein inhibition. Theoretically, increased methylprednisolone entry into the central nervous system should allow a reduction in the systemic methylprednisolone dose and a consequent decrease in glucocorticoid-mediated side effects.

Intrathecal pertussis toxin induces thermal hyperalgesia: involvement of excitatory and inhibitory amino acids

Intrathecal pertussis toxin injection has been used as a neuropathic pain model. In the present study, its effects on cerebrospinal fluid biochemistry and nociceptive behavioral expression were examined in rats. Cerebrospinal fluid dialysate samples were collected and pertussis toxin was injected using an intrathecally implanted dialysis loop catheter; samples were collected and hyperalgesia behavior was noted every 2 days for 8 days after pertussis toxin injection. Pertussis toxin injection induced thermal hyperalgesia which peaked between day 2 and 4; no cold allodynia was observed. Pertussis toxin at all doses tested (0.5, 1, or 2 μg) also induced a significant increase in cerebrospinal fluid concentrations of aspartate and glutamate between days 2 and 8, while level of the inhibitory amino acid glycine were significantly decreased by the two higher doses of pertussis toxin. Intrathecal administration of the N-methyl-D-aspartate receptor antagonist D-2-amino-5-phosponovaleric acid (10 μg) or glycine (200 μg), inhibited pertussis toxin-induced thermal hyperalgesia. Pertussis toxin injection had no effect on serine, glutamine, and taurine concentrations. These results show that intrathecal pertussis toxin injection induces thermal hyperalgesia and it is associated with an increasing of excitatory and a decreasing of inhibitory amino acids release in the spinal cord.

Comparison of endotoxin release by different antimicrobial agents and the effect on inflammation in experimental Escherichia coli meningitis.

In a rabbit Escherichia coli meningitis model, endotoxin liberation and concentrations of leukocytes, tumor necrosis factor (TNF), and lactate were compared after a single intravenous dose of cefotaxime, cefpirome, meropenem, chloramphenicol, or gentamicin. These antibiotics caused a 2- to 10-fold increase in cerebrospinal fluid concentrations of free (filterable) endotoxin within 2 h of starting treatment. By contrast, free endotoxin concentrations increased almost 100-fold in untreated animals 4 h later as bacteria continued to multiply. An initial enhancement of inflammation in the central nervous system occurred in all treatment groups compared with untreated controls. No significant differences were observed between treatment groups except for lower TNF concentrations in chloramphenicol-treated animals. Antibiotic therapy in E. coli meningitis, irrespective of the agent used, may result in an increase in free endotoxin and enhancement of inflammation, but the amount of endotoxin liberated is considerably smaller than that shed by untreated bacteria.

Prevention of chronic cerebral vasospasm in dogs with ibuprofen and high-dose methylprednisolone.

Severe chronic cerebral vasospasm was produced in dog basilar arteries by two injections, 2 days apart, of autologous blood into the cisterna magna of 25 dogs. Treatment with ibuprofen (n = 8) or high-dose methylprednisolone (n = 8) after the first injection of blood prevented or reduced angiographic vasospasm. Cerebrospinal fluid concentrations of prostaglandin E2, prostaglandin F2 alpha, 6-ketoprostaglandin F1 alpha (a metabolite of prostacyclin), and thromboxane B2 (a metabolite of thromboxane A2) were measured in both treated and untreated (n = 7) dogs. In untreated dogs, the level of prostaglandin E2 increased 94-fold by Day 8 after the first injection of blood and was strongly and positively correlated with the degree of angiographic vasospasm. Treatment with ibuprofen and high-dose methylprednisolone prevented or significantly reduced this increase in prostaglandin E2 concentration. Smaller increases in cerebrospinal fluid concentrations of thromboxane B2 and 6-ketoprostaglandin F1 alpha occurred after experimental subarachnoid hemorrhage; the magnitude of these increases was also reduced by ibuprofen or high-dose methylprednisolone treatment. In contrast, prostaglandin F2 alpha levels were not significantly altered during the study. These data show that enhanced prostaglandin E2 synthesis occurs during experimental subarachnoid hemorrhage, and the by-products generated in its synthesis may play a role in the pathogenesis of cerebral vasospasm.

The effect of different vigabatrin treatment regimens on CSF biochemistry and seizure control in epileptic patients.

1. Vigabatrin, 50 mg kg-1, was administered orally as add-on therapy to 11 patients with drug-resistant complex partial epilepsy as a single dose, then once every third day for 2 months, every other day for 2 months and daily for 1 month. 2. Lumbar punctures were carried out prior to treatment and at the end of each dosage regimen and cerebrospinal fluid (CSF) evaluated for concentrations of free and total GABA, homocarnosine (GABA-histidine dipeptide), homovanillic acid (HVA), 5-hydroxyindole acetic acid (5-HIAA) and vigabatrin. 3. Each regimen resulted in significant increases in CSF concentrations of free and total GABA and homocarnosine compared with the immediately preceding regimen. 4. CSF concentrations of HVA significantly increased after a single vigabatrin dose but returned to pre-treatment levels with subsequent dosing schedules. In contrast, 5-HIAA concentrations also increased with the single dose but were significantly decreased, compared with pre-treatment values, following alternate day and daily vigabatrin administration. 5. Seizure frequency progressively decreased with decreasing dosing interval. Daily vigabatrin administration was associated with greater than 50% decrease in seizures in 8 of the 10 patients treated.

Intraventricular microdialysis: a new method for determining monoamine metabolite concentrations in the cerebrospinal fluid of freely moving rats

A new method is described to estimate the cerebrospinal fluid (CSF) concentrations of monoamine metabolites (dihydroxyphenylacetic acid (DOPAC), homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA)) in the lateral ventricle of freely moving rats by use of in vivo microdialysis. Both the baseline concentrations of these metabolites and the rate of dopamine (DA) turnover (estimated by the accumulation of total DA metabolites after 200 mg/kg probenecid) were within the range reported when other methods were used to sample CSF. A series of preliminary studies were conducted to demonstrate that this method can be used to repeatedly sample CSF, and to show that the method is sensitive to local changes in dopaminergic activity induced by lesions, drugs or grafts. (1) Unilateral 6-hydroxydopamine (6-OHDA) lesions of the substantia nigra produced a significant decrease in the CSF concentrations of DOPAC and HVA ipsilateral to the lesion, relative to the contralateral side or to concentrations in animals without lesions. (2) When left and right lateral ventricles were sampled simultaneously in animals with a unilateral 6-OHDA lesion, haloperidol induced an increase in DOPAC and HVA concentrations in CSF on both sides of the brain. Interestingly, the haloperidol-induced increase in CSF concentrations of DA metabolites was greater adjacent to the intact striatum of rats with unilateral 6-OHDA lesions than in animals with no lesion. (3) Finally, in animals with adrenal medulla tissue grafted into the lateral ventricle there was an increase in the CSF concentration of DOPAC compared to pregraft values or to those of animals with control grafts.

Dietary problems of phenylketonuria: effect on CNS transmitters and their possible role in behaviour and neuropsychological function.

Thirty years ago it was observed that the synthesis of serotonin, dopamine and norepinephrine was impaired in untreated phenylketonuria (PKU) as judged either by a decreased concentration in the blood or decreased excretion in the urine of these neurotransmitters, or of their metabolites, 5-hydroxyindoleacetic acid (5-HIAA) and homovanillic acid (HVA). Fifteen years later, when early treatment of PKU with a phenylalanine restricted diet was routinely introduced, an inverse relationship was found between phenylalanine levels and the urinary excretion of dopamine and serotonin. An inverse relationship between blood phenylalanine levels and cerebrospinal fluid (CSF) concentrations of HVA and 5-HIAA has repeatedly been reported during the past 10 years. Recently, the effect of the discontinuation of diet in PKU on the synthesis of dopamine, norepinephrine and serotonin has been examined, and the possible relationship between low levels of these neurotransmitters and impaired performance on neuropsychological tests has been evaluated. In some PKU patients the performance on neuropsychological tests of higher integrative function is impaired after discontinuation of diet, especially when blood phenylalanine values exceed 1200 mumol/L, and the patients often complain of lack of concentration and emotional instability. When these patients return to a 'relaxed' phenylalanine restricted, tyrosine enriched diet, the impaired neuropsychological and behavioural functions appear to be reversible. One mechanism may involve an impaired synthesis of dopamine and serotonin, as the improvement is accompanied by an increase in dopamine and serotonin excretion and a significant increase in CSF concentrations of HVA and 5-HIAA.(ABSTRACT TRUNCATED AT 250 WORDS)