Space Of Rats Research Articles

Immunoisolating encapsulation of intrathecally implanted bovine chromaffin cells prolongs their survival and produces anti-allodynic effect in spinally injured rats

We have previously reported that intrathecal (i.t.) implantation of bovine chromaffin cells has an anti-allodynic effect in a rat model of mechanical and cold allodynia-like neuropathic pain after spinal cord injury. The technique of encapsulation of the cells by a semipermeable membrane has been developed recently. The present study was undertaken to investigate the effects of encapsulated bovine chromaffin cells on the allodynia-like pain in the same model. Capsules with bovine chromaffin cells or control capsules were implanted in the spinal subarachnoidal space in rats. Their response in behavioural tests were recorded for 2 months. At termination, the capsules were explanted and examined morphologically with tyrosine hydroxylase immunohistochemistry. The mechanical allodynia was totally abolished from week 2 after implantation of the cells and throughout the 8-week test period. The abnormal cold response was also attenuated in about half of the animals. The threshold to acute nociceptive stimulation was not affected. Eight weeks after implantation, 60–80% of the encapsulated chromaffin cells were still tyrosine hydroxylase positive. No effects were observed with control capsules. The results indicate that spinal implantation of encapsulated xenogeneic chromaffin cells may be useful in treating some refractory painful states associated with spinal cord injury. Immunoisolation of chromaffin cells by a semipermeable membrane may inhibit immunorejection, prolong the survival of the cells and enhance their anti-allodynic effect.

Purine and pyrimidine nucleoside content of the neuronal extracellular space in rat. An in vivo microdialysis study.

Neurological side-effects of chemotherapeutic agents1 known to act on purine and pyrimidine metabolism enzymes raised a possible role for nucleosides and deoxynucleosides in brain cell survival as it is demonstrated in recent investigations.2–5 Some new data also demonstrated the involvement of nucleotides and nucleosides in various brain functions. Apart from the well-known transmitter function of ATP6 and neuromodulator role of adenosine7 other nucleotides and nucleosides have also been suggested to be neuroactive. Pyrimidine nucleotides have specific pyrimidinoceptors even in cells of brain origin.8 Nucleosides could have their own modulatory actions as indicated by sleep modifying effect of uridine.9 The in vivo measurement of nucleosides and related substances in behaving animals could be the following major contribution to understanding the mechanisms of neurological side-effects of chemotherapeutic agents and the functional roles of nucleosides in the brain. A recently developed method, the in vivo microdialysis technique was used in the present study. Dialysis measures the composition of local extracellular space under various experimental conditions in freely moving animals.10 The main applications of microdialysis technique is measuring synaptic neurotransmitter overflow,10 investigation of transport functions, and pharmacokinetics of various drugs,11 and also gaining information about intracellular metabolic processes.12 Microdialysis has already been applied in human patients13 with subarachnoidal haemorrhage, head trauma, Parkinson’s disease, brain tumors and epilepsy.

The Effects of Different Monoaminergic Antidepressants on the Analgesia Induced by Spinal Cord Adrenal Medullary Transplants in the Formalin Test in Rats

We studied the effects of chronic intraperitoneal administration of antidepressants on the antinociception induced by adrenal medullary transplants into the subarachnoid space in rats using the formalin test.Administration of drugs started 28 days after operation and the formalin test was performed on Day 56. When amitriptyline (AMT; 15 mg [centered dot] kg-1 [centered dot] day-1) was administered to sham-operated rats, it decreased the licking time and increased the transplant-induced analgesia in Phase 1 when administered to transplanted rats. Chronic treatment with fluvoxamine (FVX, 10 mg [centered dot] kg-1 [centered dot] day-1) had no influence on the licking response in sham rats, nor did it modify the transplant-induced analgesia when administered to transplanted rats. When desipramine (DMI; 10 mg [centered dot] kg-1 [centered dot] day-1) was administered to sham rats, it significantly reduced the licking response in Phase 1, but when administered to transplanted rats it did not increase the transplant-induced analgesia. None of the drugs administered showed any effect on Phase 2 of the formalin test. These results suggest that adrenal medullary transplants into the spinal cord induce analgesia as determined by the formalin test. This effect is more pronounced when AMT (a nonselective noradrenaline-serotonin reuptake inhibitor) is chronically administered, but not when FVX or DMI are chronically administered. (Anesth Analg 1997;84:816-20)

The effects of different monoaminergic antidepressants on the analgesia induced by spinal cord adrenal medullary transplants in the formalin test in rats.

We studied the effects of chronic intraperitoneal administration of antidepressants on the antinociception induced by adrenal medullary transplants into the subarachnoid space in rats using the formalin test. Administration of drugs started 28 days after operation and the formalin test was performed on Day 56. When amitriptyline (AMT; 15 mg x kg(-1) x day(-1)) was administered to sham-operated rats, it decreased the licking time and increased the transplant-induced analgesia in Phase 1 when administered to transplanted rats. Chronic treatment with fluvoxamine (FVX, 10 mg x kg(-1) x day(-1)) had no influence on the licking response in sham rats, nor did it modify the transplant-induced analgesia when administered to transplanted rats. When desipramine (DMI; 10 mg x kg(-1) x day(-1)) was administered to sham rats, it significantly reduced the licking response in Phase 1, but when administered to transplanted rats it did not increase the transplant-induced analgesia. None of the drugs administered showed any effect on Phase 2 of the formalin test. These results suggest that adrenal medullary transplants into the spinal cord induce analgesia as determined by the formalin test. This effect is more pronounced when AMT (a nonselective noradrenaline-serotonin reuptake inhibitor) is chronically administered, but not when FVX or DMI are chronically administered.

Purine and pyrimidine nucleoside content of the neuronal extracellular space in rat. An in vivo microdialysis study

Purine and pyrimidine nucleoside content of the neuronal extracellular space in rat. An in vivo microdialysis study

Cell therapy with encapsulated xenogeneic tumor cells secreting β-endorphin for treatment of peripheral pain

The purpose of this study was to assess whether xenogeneic tumor cells secreting β-endorphin and immunologically isolated in polymer capsules could survive and continue to reduce pain when transplanted into the spinal cerebro-spinal fluid (CSF) space of rats. Also, a silicone container for polymer capsules was designed for the clinical application of this method of cell therapy. The mouse tumor cell lines, proopiomelanocortin gene transfected Neuro 2A which secrete β-endorphin, were enclosed in polymer capsules at a density of 5 × 10 6/mL, and transplanted into the spinal CSF space from the occipito-atlantal junction of male Sprague-Dawley rats. Three analgesiometric tests—the tail pinch test, the hot plate test, and electrical stimulation test — showed that the rats with encapsulated Neuro2A ( n = 6) were significantly less sensitive to pain after transplantation than control animals ( n = 8). The analgesia induced by the encapsulated cells secreting β-endorphin was attenuated by the opiate antagonist naloxone. Morphological study revealed that the encapsulated cells survived for 1 mo after transplantation into the CSF space. An in vitro experiment on cultured capsules (3 cm long) with a silicone container (Kaneka Medics Co) showed that the encapsulated Neuro2A (5 × 10 6 mL) could secrete peptides for 1 mo. The results of this study indicate that immunologically isolated xenogeneic tumor cells can secrete opiate in the CSF space, and that a silicone container may help the application of this method to the treatment of cancer pain.

Lack of lymph node reaction to subcutaneously injected silicone gel: histological and computer aided morphometric study in rats.

The gel of silicone implants may bleed through the elastomeric envelope or may come into contact with the body because of rupture of the implant. We have studied the effects of free silicone gel injected into the subcutaneous space in rats and analysed the morphological features of the axillary and inguinal lymph nodes. Ninety six Wistar rats had 3 cm3 of silicone gel injected into their subcutaneous space and 96 Wistar rats (the control group) had distilled water injected into their subcutaneous space. The animals were killed on days 1,3,7,9,15, 30,60,90,120,180,270, and 365 after the injection. There was no detectable silicone and no damage to the lymph nodes on routine histopathological analysis. Small amounts of silicone that could migrate to lymph nodes could result in hyperplasia. To evaluate this possibility, a morphometric study based on a computer aided system compared the area of lymph node sections between treated and control animals, and showed no difference between treated and control groups. If silicone did migrate, it did not provoke morphological signs or hyperplasia in the lymph nodes.

Hindlimb paralytic effects of prodynorphin-derived peptides following spinal subarachnoid injection in rats

Dynorphin A-(1–17) acts through non-opioid mechanisms to produce dose-related neurological deficits following injection into the lumbar spinal subarachnoid space in rats. Hindlimb motor function was examined following subarachnoid injection of dynorphin A fragments and other opioid peptides derived from prodynorphin to establish: (1) which portion(s) of the dynorphin A molecule cause hindlimb motor dysfunction, and (2) whether these paralytic actions are shared by other opioids (dynorphin B, α-neo-endorphin, and β-neo-endorphin) derived from the same promolecule. To minimize the influence of enzymatic inactivation on relative bioactivities, peptides were coinjected with a combination of peptidase inhibitors previously shown to enhance the actions of dynorphin A fragments in vitro. Dynorphin A-(1–17) and -(2–17) produced dose-related neurological deficits with equal potencies and durations. Although without effect when injected alone, dynorphin A-(1–8), -(1–7) and -(3–8) caused transient motor dysfunction when co-injected with peptidase inhibitors. In contrast, dynorphin A-(1–6), -(1–5) and -(6–17) did not disrupt hindlimb motor function with or without peptidase inhibition. Dynorphin B, α-neo-endorphin also caused hindlimb dysfunction which was potentiated by peptidase inhibition. These deficits appeared to result from non-opioid actions of these three peptides, since they were not blocked by the opioid antagonist naloxone. Thus, the paralytic effects of dynorphin A: (1) result from non-opioid actions involving the 3–7 or 3–8 positions of the molecule, and (2) are shared by other prodynorphin-derived opioid peptides.

An epidural intracranial pressure monitor for experimental use in the rat.

We described the construction and use of a simple and reliable catheter system that can be used to monitor intracranial pressure (ICP) from the epidural space in rats in an experimental setting. The catheter system is easily fabricated in the laboratory from readily available materials. The monitor is fitted flush with the inner table through a burr hole in the temporal squama. A side port is used to fill the system with saline and to irrigate the system should be catheter become obstructed. The distal end of the catheter is fitted to a pressure transducer that is connected to a graphic display and recording system. This system was used to record ICP in 30 anaesthetized adult rats. Seven were subjected to baseline ICP recording only and 23 were subjected to baseline recordings followed by epidural balloon compression of the contralateral hemisphere. Baseline ICP varied between 0 and 8 mmHg and respiratory variation could be detected on the tracings for 24 rats (75%). ICP responded directly and sensitively to epidural balloon inflation in all 23 rats tested. In 5 rats that died during balloon inflation, the decrease in ICP after death followed closely the loss of arterial blood pressure. There was a close correlation of numerical values obtained in two rats in which ICP was recorded simultaneously from the epidural catheter and from a catheter in the subarachnoid space at the cisterna magna. In one rat in which ICP increased to more than 70 mmHg, the epidural catheter continued to record ICP accurately while the cisternal catheter became obstructed with herniated brain.(ABSTRACT TRUNCATED AT 250 WORDS)

Thoracic epidural anaesthesia in conscious and anaesthetized rats. Effects on central haemodynamics compared to cardiac beta adrenoceptor and ganglionic blockade

A simple technique for cannulation of the thoracic epidural space in rats was described. 40-50 microliter of epidural bupivacaine 5 mg/ml induced a distribution of sensory analgesia from lower cervical to lower thoracic segments. With this model, effects of thoracic epidural anaesthesia (TEA) on mean arterial pressure (MAP), cardiac output (CO), systemic vascular resistance (SVR), stroke volume (SV), heart rate (HR), central venous pressure (CVP), left ventricular end-diastolic pressure (LVEDP) and maximal increase of pressure in the left ventricle (max dp/dt) were studied in six groups of animals: 1) In conscious animals (n = 10) MAP, CO, SV and HR decreased significantly by 12%, 25%, 10% and 16%, respectively, while SVR increased significantly by 20% during TEA; 2) In chloralose-anaesthetized animals (n = 7) the reduction in CO during TEA was less pronounced and there were no significant changes in SV or SVR; 3) In conscious animals (n = 6) LVEDP, CVP and max dp/dt decreased significantly during TEA; 4) Hexamethonium, when administered to pharmacologically vagotomized conscious animals during TEA (n = 8), induced a significant decrease in SVR (23%) but no change in HR; 5) Changes in haemodynamics after cardiac adrenoceptor blockade with metoprolol, in conscious animals (n = 12), did not differ significantly from those seen during TEA, except for an unchanged SV after metoprolol; 6) 50 microliters of bupivacaine (5 mg/ml) when given i.v. to conscious animals (n = 8) did not affect CO, SV, HR or TPR significantly, while MAP increased slightly but significantly. Thus, in this conscious animal model, TEA almost completely and rather selectively blocked probably mediated by a reflex activation of unblocked sympathetic efferents.(ABSTRACT TRUNCATED AT 250 WORDS)

Intrathecal morphine induces myoclonic seizures in the rat.

The development of myoclonic activity as a toxic effect of morphine application into the intrathecal space in rats is described. This syndrome resembled the human syndrome of action myoclonus by its spontaneous onset and its augmentation by initiation of movement or by an acoustic stimulus. It was not reversed or prevented by naloxone. This effect of morphine was associated with an increase in serotonergic activity in the spinal cord and was reduced by pretreatment with parachlorophenylalanine in doses which reduced spinal 5-HT by approximately 60%. The dose which produced this syndrome was about ten times higher than the analgesic dose applied by the same route. Other commonly used opiates such as: methadone (0.5-2 mg/kg), pethidine (2-10 mg/kg), fentanyl (2-10 micrograms/kg) and ketamine (2-10 mg/kg) did not produce myoclonic-like activity, but methadone and pethidine at the highest doses caused respiratory arrest. Fentanyl appeared to be the safest of the drugs tested since a relatively high dose, administered into the intrathecal space did not cause any side effects, while morphine was least safe of the five drugs since it produced myoclonic activity in addition to the widely documented respiratory depression. We suggest that the production of the myoclonic activity is mediated by spinal serotonergic systems.

Compliance of the interstitial space in rats. III. Contribution of skin and skeletal muscle interstitial fluid volume to changes in total extracellular fluid volume.

The contribution to the extracellular fluid volume (ECV) from plasma volume (PV) and the total interstitial volumes contained in skin ( IFVS ) and skeletal muscle ( IFVM ) has been studied in rats over a wide range of overhydration and dehydration. ECV was measured as the two-hour distribution space for 51Cr-EDTA after nephrectomy while PV was measured with radiolabelled albumin or erythrocytes. Total interstitial volumes in skin and skeletal muscle were calculated from measurement of local interstitial volumes and the amount of skin and skeletal muscle in the rat. In control conditions ECV was on average 24.12 ml/100 g body weight. PV was 11.0% of ECV in control while IFVS and IFVM was 28.1% and 19.0% respectively. In dehydration the change in PV was 13.3% of the change in ECV, while the change in IFVS and IFVM was 30.0% and 21.0% of the change in ECV respectively. In overhydration (ECV on average 33.76 ml/100 g rat) the changes in PV, IFVS and IFVM were 7.5%, 22.1% and 17.2% of the change in ECV respectively. The regression coefficients describing the change between ECV and IFVS and IFVM were not significantly different in overhydration and dehydration while the regression coefficient between ECV and PV in overhydration was significantly less than the regression coefficient in dehydration. Thus, the fraction of ECV contained in skin and skeletal muscle is similar over the range of hydration studied. The fraction of ECV located in plasma is similar in control and dehydration, while in overhydration less of ECV is localized in plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Compliance of the interstitial space in rats. II. Studies on skin.

Interstitial compliance, defined as the ratio between changes in interstitial fluid volume (delta IFV) and interstitial fluid pressure (delta IFP), has been measured for rat skin. IFP has been measured with sharpened glass capillaries connected to a servocontrolled counterpressure system, while IFV has been determined as the extravascular distribution space for 51Cr-EDTA. The measurements were performed at hydration and dehydration of various duration. Compliance was 0.162 ml/g dry tissue per mmHg in dehydration, corresponding to 5.4 ml/100 g wet tissue per mmHg. The volume-pressure curve was similar at 2-4 and 24-28h of dehydration. Up to 20% increase in IFV compliance was similar to that in dehydration, but thereafter increased severalfold upon further increase in IFV. Even at sixfold increase in IFV, IFP did not rise by more than 1 to 2 mmHg. Control IFV in skin amounts to 40 ml/100 g wet tissue and IFV will therefore change by 14% when IFP changes by 1 mmHg from the control level. This change in IFV will cause interstitial fluid colloid osmotic pressure to increase or decrease by somewhat more than 1 mmHg in dehydration or hydration respectively from a normal control level of about 9 mmHg. With further increase in IFV secondary to increased capillary filtration, the interstitial edmaprevention will depend on washout and/or dilution of interstitial proteins since IFP did not increase by more than 1 to 2 mmHg.

Compliance of the interstitial space in rats. I. Studies on hindlimb skeletal muscle.

Interstitial compliance, defined as the ratio between changes in interstitial fluid volume (delta IFV) and interstitial fluid pressure (delta IFP), was determined for rat skeletal muscle. IFV was measured as the extravascular distribution space for 51Cr-EDTA, while sharpened micropipettes connected to a servo-controlled counterpressure system were used to measure IFP. The experimental protocol was designed to bring about acute (2-4 h) and chronic (24-28h) tissue over- and dehydration. During dehydration, the average compliance was 0.056 ml/g dry weight . mmHg, corresponding to 1.40 ml/100 g wet tissue . mmHg, and was not significantly different in acute and chronic experiments. In hydration (acute and chronic), compliance increased several-fold when IFV increased. Even at greatly increased IFV, IFP did not rise more than 1 to 1.5 mmHg above control level. Since control IFV amounts to 10 ml/100 g wet tissue, IFV will decrease by 14% when IFP falls by 1 mmHg from this control level. Provided unchanged interstitial protein mass the dehydration will cause interstitial fluid colloid osmotic pressure to increase by somewhat more than 1 mmHg--from a control level of 9 mmHg. Furthermore, since IFP was not increased by more than 1 to 1.5 mmHg during hydration, an increase in IFP plays a minor role in edema-prevention compared to dilution and/or washout of interstitial proteins.

Long term catheterization of the lumbar epidural space in rats

This note describes a simple technique for the administration of drug solutions into the lumbar epidural space of the unanesthetized and freely moving rat. A poly-ethylene (PE-10) catheter is inserted into the epidural space through a hole in the third lumbar vertebra, and subcutaneously tunneled towards the neck region. The implantation procedure is well-tolerated, and repeated saline injections over a prolonged period of time were found not to exert any deleterious effect on the animals' apparent health or gross behavior. The viability of the technique is demonstrated in an experiment on the effect of injection volume on the analgesic action of epidurally administered fentanyl.

Commentary: Asbestos Fibers in the Colonic Wall

As part of a long-term study, rats were fed a standard diet consisting of 65% cellulose, some casein, and a salt mix together with 6% of fairly pure chrysotile. After 3 months on this diet some of the rats were sacrificed and their colonic mucosa examined with the electron microscope. Two types of fixation were used: potassium permanganate and osmium. The permanganate gives very little cellular detail, but this is ideal in scanning large numbers of fields for asbestos fibers. The small chrysotile particles were easily distinguished by the typical concentric double tubule structure. These particles were found in the mucus of the goblet cells, within the cytoplasm of the epithelial cells, and down into the smooth muscle layers. We tried to eliminate the possibility of these findings being artifacts. Many of the fibers appeared in seciton, indicating that they had been embedded in the tissue at an angle to the knife and were genuine cell enclosures. To eliminate the possibility that fibers from the lumen of the gastrointestinal tract had been pushed into the section, we eliminated asbestos from the diet of other rats for 3 days, at which time no fibers could be found in the feces. Particles were still present in the tissues, although in smaller numbers, probably due to clearance processes. It was interesting to note that we could find no membrane surrounding the fibers in the cells; the fibers did not appear to be situated in lysosomes or phagosomes. This is in line with another study that we performed, looking at phagocytes with asbestos, in which some of the fibers appeared to be in the cytoplasm and not bounded by a membrane. Continued observation of the surviving rats did not reveal the development of any tumors. In another experiment we placed pellets of chrysotile in the pleural space of rats. After some months the pellets were organized by fibroblasts and invaded by histiocytes. Within the histiocytes we found phagocytic vacuoles containing asbestos. We also found that the characteristic structure of the chrysotile changed gradually, becoming amorphous. We postulated that some of the magnesium or silicate had been removed. We checked this by putting some chrysotile in an acid medium and found that there was leaching when the fibers were examined by the electron microscope. With appropriate staining methods we concluded that chrysotile can be broken down in lysosomes with the formation of polysilicic acids.

Comparison of external loss of sodium with loss from sucrose space in adrenalectomized rats.

Using 1-hour sucrose space in rats as a measure of extracellular fluid (ECF) volume, net loss of Na from ECF is found to agree closely with external loss (balance data) 6 days after adrenalectomy. No significant exchange of Na between ECF and intact cells is evident following adrenalectomy. Fair correspondence of net loss of Na from ECF with external loss was also seen in normal rats mildly depleted of Na by 6 days on an essentially Na-free diet. Sucrose space (ml/kg final weight) is 225 ± 12 in normal rats, 197 ± 13 in adrenalectomized, and 209 ± 9 in normal rats after 6 days on an essentially Na-free diet. Evidence is presented that sucrose space measure a reproducible ECF compartment in normal, adrenalectomized and salt-depleted rats.

Bestimmung des extracellul�ren Raumes von Ratten mit Hilfe von Inulin

A method has been described which permits the use of inulin as a measure of the extracellular space of rats, by means of an equilibrating infusion followed by the collection of the total inulin excreted. The blood used for the measuring of inulin plasma concentration is taken from the retroorbital vein plexus. The average extracellular space of the rat is 20,9 per cent of the body weight.

Whole body and tissue inulin and sucrose spaces in the rat.

Whole body inulin space in nephrectomized rats, calculated as found inulin/concentration in plasma water, rises exponentially with time, equalling water extractable Na space at about 15 hours, total body water at about 48 hours, and exceeding body volume at 68 hours. The rise is due to inulin stored in cells, cell entry proceeding at high complex rates in liver and spleen and at lower exponential rates in skin and skeletal muscle. Inulin space is initially lower than sucrose space, but rises faster. It overtakes sucrose at 9 hours and progressively exceeds it thereafter. The only meaningful expression of space in nephrectomized animals is obtained by taking plasma water level extrapolated to zero time. Nephrectomy 24 hours prior to inulin injection does not influence the results, indicating that cell permeability to inulin is not significantly changed after nephrectomy. The continuous infusion (with postinfusion recovery) method probably gives correct values in intact subjects because the intracellular inulin is not recovered during collection.

NORMAL BLOOD VOLUME, PLASMA VOLUME AND THIOCYANATE SPACE IN RATS AND THEIR RELATION TO BODY WEIGHT

NORMAL BLOOD VOLUME, PLASMA VOLUME AND THIOCYANATE SPACE IN RATS AND THEIR RELATION TO BODY WEIGHT