Cerebrospinal fluid flow increases from newborn to adult stages.

Solute transport through the brain is of major importance for the clearance of toxic molecules and metabolites, and it plays key roles in the pathophysiology of the central nervous system. This solute transport notably depends on the cerebrospinal fluid (CSF) flow, which circulates in the subarachnoid spaces, the ventricles and the perivascular spaces. We hypothesized that the CSF flow may be different in the perinatal period compared to the adult period. Using in vivo magnetic resonance imaging (MRI) and near-infrared fluorescence imaging (NIRF), we assessed the dynamic of the CSF flow in rodents at different ages. By injecting a contrast agent into the CSF, we first used MRI to demonstrate that CSF flow gradually increases with age, with the adult pattern observed at P90. This observation was confirmed by NIRF, which revealed an increased CSF flow in P90 rats when compared with P4 rats not only at the surface of the brain but also deep in the brain structures. Lastly, we evaluated the exit routes of the CSF from the brain. We demonstrated that indocyanine green injected directly into the striatum spread throughout the parenchyma in adult rats, whereas it stayed at the injection point in P4 rats. Moreover, the ability of CSF to exit through the nasal mucosa was increased in the adult rodents. Our results provide evidence that the perinatal brain has nonoptimal CSF flow and exit and, thus, may have impaired clean-up capacity. © 2018 Wiley Periodicals, Inc. Develop Neurobiol, 2018.

Perinatal Asphyxia May Influence the Level of Beta-Amyloid (1-42) in Cerebrospinal Fluid: An Experimental Study on Newborn Pigs.

OBJECTIVE: Total tau (T-tau), phosphorylated tau (p-Tau) and Beta-Amyloid 1-42 (AB42) in Cerebrospinal Fluid (CSF) are useful biomarkers in neurodegenerative diseases. The aim of the study was to investigate the role of these and other CSF biomarkers (T-tau, p-Tau, AB42, S100B and NSE), during hypoxia-reoxygenation in a newborn pig model. DESIGN: Thirty newborn pigs were included in a study of moderate or severe hypoxia. The moderate hypoxia group (n = 12) was exposed to global hypoxia (8% O2) until Base excess (BE) reached -15 mmol/l. The pigs in the group exposed to severe hypoxia (n = 12) received 8% O2 until BE reached -20 mmol/l or mean Blood Pressure fell below 20 mm Hg, The control group (n = 6) was kept at room air. For all treatments, the CSF was collected at 9.5 hours after the intervention. RESULTS: The level of AB42 in CSF was significantly lower in the pigs exposed to severe hypoxia compared with the control group, 922(SD +/-445)pg/ml versus. 1290(SD +/-143) pg/ml (p<0.05), respectively. Further, a non-significant reduction of AB42 was observed in the group exposed to moderate hypoxia T-tau and p-Tau revealed no significant differences between the intervention groups and the control group, however a significantly higher level of S100B was seen in the CSF of pigs receiving hypoxia in comparison to the level in the control group. Further on, there was a moderate negative correlation between the levels of AB42 and S100B in CSF, as well as a moderate negative correlation between Lactate in blood at end of hypoxia and AB42 in CSF. INTERPRETATION: This is the first study to our knowledge that demonstrated a significant drop in AB42 in CSF after neonatal hypoxia. Whether or not this has an etiological basis for adult neurodegenerative disorders needs to be studied with additional experiments and epidemiological studies. AB42 and S100B are significantly changed in neonatal pigs subjected to hypoxia compared to controls and thus may be valuable biomarkers of perinatal asphyxia.

[Reference values in the cerebrospinal fluid of calves between four and eight weeks of age]. / Referenzwerte im Liquor cerebrospinalis bei Kälbern im Alter von vier bis acht Wochen.

Reference values for the following parameters were established in the cerebrospinal fluid of 27 calves between four and eight weeks of age: specific weight, protein concentration, erythrocyte count, total leucocyte count with cell differentiation, creatin kinase activity, glucose and sodium. If possible, the findings were compared with those of other authors in calves and adult bovines. With 24.3 cells per microliter the 90% quantile of the total leucocyte count was seated significantly above comparable values for adult bovines. Hence, in individual cases markedly higher leucocyte counts can be expected in the cerebrospinal fluid of calves. In agreement with other authors, the protein concentration in calves was lower than in adult bovines. The reference range for creatin kinase activity was increased whereas the one for sodium was only slightly increased compared to earlier investigations in calves and in adult bovines.

Transport of colostral macromolecules into the cerebrospinal fluid via plasma in newborn calves.

The objective of this study was to investigate the transfer of bovine colostral macromolecules especially the lactoferrin (Lf), transferrin (Tf), immunoglobulin G (IgG), and epidermal growth factor (EGF) from the gastrointestinal tract to the cerebrospinal fluid (CSF) via systemic circulation in newborn calves. Cannulae were placed into the jugular vein and cisterna magna to collect blood and CSF, respectively at various time points. The colostrum, plasma, and CSF were analyzed by ELISA, SDS-PAGE, two-dimensional PAGE, and Western blotting. The concentration of total protein, Lf, Tf, and IgG in plasma averaged 47 mg, 204 ng, 101 microg and 15 microg/ml before colostrum feeding and increased to the peak values of 64 mg, 2413 ng, 820 microg, and 4608 microg/ml 8 h after feeding, respectively. Before colostral feeding CSF, total protein, Lf, Tf, and IgG averaged 0.44 mg, 10.3 ng, 0.31 microg, and 0.11 microg/ml, but peak values after feeding averaged 2.0 mg, 173 ng, 71 microg and 72 microg/ml after 10 h, respectively. Immunologically, six EGF-positive protein bands were detected in colostrum as well as in three bands higher density in plasma and CSF after colostral feeding. This study revealed that the colostral macromolecules were not only absorbed into the systemic circulation, but also some of them including Lf, Tf, IgG, and EGF-like proteins were transported into the CSF in a time-dependent manner through blood-CSF or blood-brain barrier of the newborn calves.

Acidic amino acid clearance from CSF in the neonatal versus adult rat using ventriculo-cisternal perfusion.

The acidic amino acids aspartate and glutamate are excitatory neurotransmitters in the CNS. The clearance of this group of amino acids from CSF of adult and neonatal (7-day-old) rats was investigated. Ventriculo-cisternal perfusions with 14C-amino acids and 3H-dextran were carried out for up to 90 min. Uptake of the amino acids by the whole brain was measured, and the loss to blood was calculated. 3H-Dextran was included in the perfusate for measurement of CSF secretion rate. After 90-min perfusion, both aspartate and glutamate showed a similar uptake into the whole brain, and this did not change with age (p>0.05). However, clearance from CSF was greater in the adult, as was entry into blood from CSF. Addition of 5 mM excess unlabelled amino acid resulted in reduction in the brain uptake of both 14C-amino acids in the adult rat. In the neonate, addition of aspartate also reduced brain aspartate uptake, whereas addition of glutamate increased brain neonatal [14C]glutamate uptake. The rate of CSF secretion was significantly greater in the adult, 1.26+/-0.18 microl x min(-1) x g(-1), than in the neonate, 0.62+/-0.08 microl x min(-1) x g(-1), and the turnover of CSF was greater in adults (p<0.01). In summary, both aspartate and glutamate showed greater clearances from CSF in the adult than the neonate. This clearance was found to be by carrier-mediated mechanisms.

CSF glutamate during hypoxia-ischemia in the immature rat.

Cerebrospinal fluid (CSF) glutamate was measured prior to and during the course of cerebral hypoxia-ischemia in the immature rat to estimate its concentration in the extracellular fluid (ECF). A preliminary experiment was conducted using [14C]glutamate injections into immature rat brain, which showed that equilibration between ECF and CSF occurred within 10 min. Seven-day postnatal rats underwent unilateral common carotid artery ligation followed by hypoxia with 8% oxygen for up to 2 h. Brain damage, in the form of selective neuronal necrosis or apoptosis, commences after 60 min, while infarction commences after 90 min of hypoxia-ischemia. During the course of hypoxia-ischemia, CSF was obtained from the cisterna magna and analyzed for glutamate. No statistically significant increases in CSF glutamate occurred until 105 min, at which time the concentration was 240% of control (20 micromol/l). By 120 min, CSF glutamate had increased over twofold above the control value. In rat pups exposed to 1 h of hypoxia-ischemia, no increases in CSF glutamate occurred for up to 6 h of recovery. In animals exposed to 2 h of hypoxia-ischemia, CSF glutamate decreased to the control value by 1 h of recovery, with a secondary rise at 6 h. Accordingly, the increase in CSF, and presumably ECF, glutamate is a late event, which better corresponds temporally to cerebral infarction than to selective neuronal death. The results suggest that glutamate excitotoxicity, although involved in the occurrence of infarction, neither causes or contributes to selected neuronal death. The secondary elevation in CSF glutamate at 6 h of recovery from 2 h of hypoxia-ischemia occurs coincident with the onset of tissue necrosis, seen histologically.

Characteristic transfer of colostral components into cerebrospinal fluid via serum in neonatal pigs.

In order to evaluate the possibility of modification of brain function by colostral suckling, the characteristic transfer of colostral components into serum and cerebrospinal fluid (CSF) has been studied by SDS electrophoresis, immunoblot and ELISA methods in nonsuckling pigs. Total protein concentrations in the serum increased immediately after oral administration of bovine colostrum, reaching a peak value (7.0 +/- 0.7 g/dl) at 24 h after administration, corresponding to a 3-fold increase compared to preinfusion levels. IgG and other macromolecular components (MW 19, 000-58,000) were recognized in serum by electrophoretic and ELISA analysis. Total protein concentrations in the CSF collected from the cisterna magna also increased steeply after colostral administration, reaching a maximal value (54.1 +/- 5.0 mg/dl) at 4 h, corresponding to a 4-fold increase compared to preinfusion levels. Two colostral components (MW 19,000 and 31,000) in serum were confirmed to be present in the CSF by electrophoresis. The component of MW 19,000 was identified by immunoblot as beta-lactoglobulin. IgG in serum transferred from colostrum could not be detected in the CSF by ELISA. Lactoferrin administered into the intestine was also detected in the CSF via serum. These results indicate that some components of colostrum can be transported into the CSF via the serum, suggesting the possibility of modification of immature brain functions by colostral suckling in neonatal pigs.

Effects of continuous infusion fentanyl citrate on cerebrovascular and systemic prostanoids in postsurgical newborn piglets.

BACKGROUND: Newborns admitted to the intensive care unit undergo multiple painful procedures. Fentanyl citrate (FC) is one of the most commonly used drugs for pain relief in the newborn. Although it has been reported that one of the biological effects of fentanyl is hemodynamic stability, the response of systemic and/or cerebrovascular prostanoids to FC infusions have not been studied. METHODS: To examine the effects of continuous intravenous (IV) infusion of FC on systemic and cerebrovascular prostanoid concentrations, two groups of spontaneously breathing newborn piglets (1-3 days old) were studied. The study group (n = 6) and the control group (n = 8) were respectively given a loading dose of 30 micrograms/kg IV over 15 minutes, immediately followed by a continuous IV infusion of 10 micrograms/kg/hr for 6 hours, or a placebo (PB) solution of 5% dextrose in a similar fashion. Cerebrospinal fluid (0.5 mL) from cisterna magna puncture and blood samples (1.0 mL) from the sagittal sinus vein and carotid artery were collected serially before and after FC or PB infusion for drug and PG determinations. FC was measured by high pressure liquid chromatography (HPLC), and the prostanoids were measured using enzyme immunoassay (EIA) kits. RESULTS: FC infusion induced marked elevations in 6-ketoPGF1 alpha (300%, p < 0.001) and TXB2 (150%, p < 0.001) at 30 minutes, and remained elevated up to 2 hours of infusion. In addition, systemic 6-ketoPGF1 alpha increased by 180% (p < 0.001) and PGE2 concentrations fell dramatically at 30 minutes (87%, p < 0.001) and did not return to normal levels during the infusion time (83% to 81%, p < 0.001 to p < 0.01). CSF 6-ketoPGF1 alpha and TXB2 levels increased by 152% and 80%, respectively (p < 0.001), but PGE2 decreased by 76% (p < 0.001), at 6 hours of infusion. An inverse relationship existed between FC, and sagittal sinus PGE2 levels (r = 0.46, p < 0.03) and systemic PGE2 levels (r = 0.602, p < 0.02). CONCLUSION: The data suggest FC is rapidly transported across the blood brain barrier and the effects on cerebrovascular prostanoids, particularly PGE2 is rapid and prolonged. PGE2 appears to be the primary responsive prostanoid. The magnitude of the response, as evidenced by the early and sharp reductions in systemic and cerebrovascular concentrations, suggest vasoconstriction, with possible adverse effects on organ blood flow and metabolic activity. However, further studies are required to evaluate the effects on organ blood flow and metabolism.

Cerebrospinal fluid concentrations of glutamate and GABA during perinatal cerebral hypoxia-ischemia and seizures.

Cerebrospinal fluid (CSF) concentrations of glutamate and gamma- aminobutyric acid (GABA), as estimates of levels in the extracellular compartment of brain, were determined in 7-day postnatal rats at the terminus of hypoxia-ischemia and during status epilepticus, induced with bicuculline, at 2 and 24 h of recovery. Hypoxia-ischemia was associated with increased CSF glutamate, which was not increased further during status epilepticus. In contrast, CSF GABA was increased by hypoxia-ischemia as well as by status epilepticus during recovery. CSF glutamate/GABA ratios in rat pups subjected to status epilepticus with or without prior hypoxia-ischemia were lower than control animals during recovery. The lack of any significant increase in glutamate or in the glutamate/GABA ratio during status epilepticus would preclude any neuronal injury from occurring in those immature rats sustaining seizures alone or any accentuation of brain damage in those animals subjected to prior cerebral hypoxia-ischemia.

A field study of ovine bacterial meningoencephalitis.

Bacterial meningoencephalitis most commonly affected lambs two to four weeks old (median three weeks, range three days to six months) with clinical signs of episcleral congestion, lack of suck reflex, weakness, altered gait and depression extending to stupor, but hyperaesthesia to auditory and tactile stimuli. Opisthotonos was observed during the agonal stages of the disease. Analysis of lumbosacral cerebrospinal fluid revealed a highly significant increase in protein concentration (P < 0.01) with a neutrophilic pleocytosis, but bacteriological culture yielded organisms in only a few cases. A response was achieved with high doses of dexamethasone and chloramphenicol in only one of 20 cases. Polyarthritis and liver abscesses in a number of lambs provided evidence of a previous bacteraemic or septicaemic episode but no definite source of the central nervous system infection was identified. In common with other infectious bacterial conditions which are prevalent during the early life of sheep, control measures should ensure an adequate transfer of passive antibody, repeated treatments of the navel, and hygienic conditions in the lambing and rearing environments.

Prostaglandin E2 in cerebrospinal fluid of fetal and newborn sheep: central versus peripheral source.

During the perinatal period, prostaglandin (PG) E2 levels show parallel changes in cerebrospinal fluid (CSF) and blood which may be important for the adaptation of the fetus to extrauterine life. It is not known, however, whether PGE2 in the CSF originates from a local or a peripheral source. Experiments were carried out in term fetal and newborn sheep chronically instrumented with a cannula inside the third ventricle and vascular lines. Indomethacin was given intracerebroventricularly (i.c.v.) (50 or 100 micrograms at hourly intervals), alone or in combination with intravenous (i.v.) PGE2 (1 or 1.5 micrograms/kg/min). In the fetus, i.c.v. indomethacin reduced PGE2 levels in both CSF and plasma. Conversely, no significant change was noted at either site when indomethacin was given i.c.v. to the newborn. At both ages, PGE2 increased in the CSF during i.v. infusion of the compound, but this elevation was proportionately smaller than in plasma. We conclude that, in the perinatal period, brain and peripheral circulation function as separate compartments with respect to PGE2, though there is passage of the compound across the blood-brain barrier. Results provide indirect evidence that perinatal brain produces PGE2 in measurable amounts.

Eicosanoids in third ventricular cerebrospinal fluid of fetal and newborn sheep.

A method to serially sample cerebrospinal fluid (CSF) from the third ventricle of chronically catheterized fetal and newborn sheep was developed. Either sampling cannulas of preset lengths ("fixed-probe" technique) or a single cannula that could be positioned at the desired depth ("roving-probe" technique) was used. The roving probe proved superior because free CSF flow was obtained in seven of ten animals after surgery compared with two of nine animals implanted with a fixed probe. CSF (5 animals) and plasma (7 animals) was collected serially from 2 wk before to 2 wk after birth, including the time around labor. Prostaglandin E2 (PGE2) levels (means +/- SE) were significantly higher in CSF (366 +/- 120 pg/ml; n = 5) and plasma (520 +/- 69 pg/ml; n = 7) before the day of delivery than in the same animals after birth. During labor, CSF and plasma PGE2 levels increased significantly to 1,428 +/- 643 pg/ml in CSF and to 2,015 +/- 414 pg/ml in plasma. However, by 1 h after birth, PGE2 had fallen to 366 +/- 165 pg/ml in CSF and to 338 +/- 106 pg/ml in plasma; levels similar to those observed in the fetus before labor. PGE2 continued to decrease precipitously and, at 24 h of age, levels were significantly less than those observed in the fetus. PGE2 levels were near the limit of detection of the assay in CSF (< 5 pg/ml) and were 49 +/- 10 pg/ml in plasma. In contrast, CSF thromboxane B2 (n = 2) and total peptidoleukotriene content (n = 4) showed little change during labor or after birth.(ABSTRACT TRUNCATED AT 250 WORDS)

High-frequency oscillatory ventilation compared with conventional mechanical ventilation in newborn lambs: effects of increasing airway pressure on intracranial pressures.

We tested the hypothesis that intracranial pressures and cerebral perfusion pressure in the newborn are more seriously affected by increasing airway pressure during high-frequency oscillatory ventilation (HFOV) than during conventional mechanical ventilation (CMV). Mean airway pressure was acutely elevated in stepwise fashion to 25 cm H2O in six anesthetized, paralyzed newborn lambs. Pressure (mean +/- SE) increased similarly during HFOV and CMV in the jugular vein (7 +/- 1 and 8 +/- 1 cm H2O, respectively), the sagittal sinus (6 +/- 1 and 7 +/- 1 cm H2O), and the cerebrospinal fluid of the lateral ventricle (4 +/- 1 and 6 +/- 1 cm H2O). Decreases in arterial blood pressure (-13 +/- 2 and -10 +/- 2 cm H2O) and cerebral perfusion pressure (-17 +/- 2 and -16 +/- 2 cm H2O) were also similar during HFOV and CMV. Intracranial pressure-volume curves were generated by incrementing cerebrospinal fluid volume in eight lambs. Curves generated during HFOV and CMV were similar, reflecting a similar intracranial compliance during the two ventilatory modes. These data indicate that intracranial compliance and the effects of increasing airway pressure upon intracranial pressures are not significantly different between HFOV and CMV.

Biochemical constituents of cerebrospinal fluid in premature and full term foals.

Total protein content and a variety of enzyme activities and electrolyte values were determined in 73 cerebrospinal fluid (CSF) samples from 66 horses and ponies. The foals (48) were divided into 3 categories-spontaneously delivered normal foals (Group A), full term induced normal foals (Group B) and premature induced non-surviving foals (Group C). CSF samples from a group of 18 normal adults (Group D) were included for comparison. Paired serum and CSF samples were collected on 32 occasions and subjected to similar analyses. CSF sodium and chloride were always higher than serum sodium and chloride; the reverse occurred with potassium. The CSF protein and enzyme levels were always lower than corresponding serum values. The foals had higher total protein and creatine kinase in CSF than the adults, except for Group C (non-survivors) which had significantly lower creatine kinase than either of the other 2 foal groups. Creatine kinase values tended to fall towards adult levels over 40 h post partum. It was also noted that foals with both high total protein and creatine kinase in CSF, compared with adult values, had a better chance of survival than those with high total protein but low creatine kinase.

The effects of acute total asphyxia and metabolic acidosis on cerebrospinal fluid bicarbonate regulation in newborn puppies.

We evaluated CSF [HCO3-] regulation in lightly anesthetized newborn puppies following: (1) acute total asphyxia; (2) metabolic acidosis; and (3) metabolic acidosis induced after acute asphyxia. Five and one-half min of total asphyxia resulted in a 4.4 mM/liter decrease in mean CSF [HCO3-]. During 65 min of recovery with mechanical ventilation mean CSF [HCO3-] increased 1.7 mM/liter. Mean plasma [HCO3-] decreased 7 mM/liter and recovered 4.5 mM/liter in the same period. We produced a stable metabolic acidosic for 4 hr using a peritoneal dialysis technique with PaCO2 maintained at the normal value. With acidosis in nonasphyxiated control puppies, CSF [HCO3-] decreased steadily. At 4 hr, the ratio, delta CSF [HCO3-]/delta plasma [HCO3-], was 0.43, a value close to that observed in adults of many species with metabolic acid-base disturbances, 0.41. With acidosis in asphyxiated puppies allowed 1 hr of recovery, the time course and mean values of plasma and CSF [HCO3-] were indistinguishable from those of the nonasphyxiated acidotic controls. Newborn puppies appear to regulate CSF [HCO3-] in response to acute asphyxia or metabolic acidosis, and acute asphyxia does not impair the puppy's ability to regulate CSF [HCO3-] in metabolic acidosis.

Model of neonatal meningitis caused by Escherichia coli K1 in guinea pigs.

A total of 88 neonatal guinea pigs was inoculated intranasally with a clinical isolate of Escherichia coli K1 that had been passaged once in the peritoneum of an adult guinea pig; 74 animals became bacteremic, of which 54 had meningitis, 12 hr after inoculation. Bacteremia and/or meningitis occurred consistently in repeated experiments. It was possible to obtain serial specimens of cerebrospinal fluid by cisternal puncture without killing the animals. The induction of meningitis in a predictable fashion without disrupting the blood-brain barrier and the ability to study the cerebrospinal fluid without killing the animal make this a useful model of human neonatal meningitis caused by E. coli K1.