Comparisons of the Effects of Anesthesia and Stress on Release of Tumor Necrosis Factor-α, Leptin, and Nitric Oxide in Adult Male Rats

The effects of repeated doses of xylazine-ketamine and medetomidineketamine anesthesia on DNA damage in the liver and kidney

PURPOSE

This study evaluated the DNA damage caused by repeated doses of xylazine-ketamine and medetomidine-ketamine anesthesia in the liver and kidneys.

METHODS

In this study, 60 rats were used. The rats were divided into group 1 (xylazine-ketamine), and group 2 (medetomidine-ketamine), and these anesthetic combinations were administered to the rats at repeated doses with 30-min intervals. The effects of these anesthetic agents on the tumor necrosis factor-alpha gene for DNA damage were investigated.

RESULTS

According to the gene expression results, it was observed that a single dose of xylazine-ketamine was 2.9-fold expressed, while first and second repeat doses did not show significant changes in expression levels. However, in the case of the third repetition, it was observed to be 3.8-fold overexpressed. In the case of medetomidine-ketamine administration, it was observed that a single-dose application resulted in a 1.04-fold expression, while the first and the third repeat doses showed a significant down expression. The samples from the second repeat dose administration group were found to have insignificant levels of expression.

CONCLUSIONS

This study can contribute to understanding the safe anesthetic combination in research and operations in which xylazine-ketamine and medetomidine-ketamine combinations are used.

Effects of Sodium Chloride-Rich Mineral Water on Intestinal Epithelium. Experimental Study

Since knowledge concerning the cellular and tissue substrate that explains the therapeutic action of mineral waters is generally very scarce, we address the different effects that Lanjarón-Capuchina mineral water exerts on the intestinal epithelium in an experimental model as a prototype of the sodium chloride-rich mineral waters used in digestive disorders. In the experimental protocol, two groups of five adult Wistar rats received unrestricted mineral water in their diet or mineral water directly into the gastrointestinal tract through a catheter. A third control group was given a standard diet and water ad libitum. Intestinal samples for scanning electron microscopy were analyzed according to standardized methods. The observations carried out by microscope after the administration of the sodium chloride-rich mineral water clearly indicate that the hypertonic action of this mineral water affects the structure of the intestinal epithelium. It modifies the microvilli absorption in terms of the groups of enterocytes and the secretion of goblet cells, but it particularly affects the epithelial renewal process, accelerating and stimulating cell extrusion. The type of extrusion mechanism observed by microscope allows us to affirm that, although this increased after direct administration, it does not generate an epithelial disruption as it occurs in other circumstances with other extrusion modalities.

Effect of Ketamine on Cocaine-Induced Immunotoxicity in Rats

The abuse of cocaine (COC) with ketamine (KET) is currently popular among young drug abusers and has been associated with increased risk of human immunodeficiency virus (HIV) infection. The effect of subacute exposure to COC and KET alone and in combination on the immune system was assessed in adult male Sprague-Dawley (SD) rats. To simulate the route and mode of human exposure, rats were treated with COC alone (5 mg/kg, IV), KET alone (100 mg/kg, PO) or KET followed immediately by COC (same doses and routes of administration) once-a-day for 7 consecutive days. Rats were sacrified 30 minutes following the last treatment. Total circulating leukocyte and lymphocyte counts were decreased with relative neutrophilia, whereas immunoglobulin M (Ig M) antibody response to sheep erythrocytes (SRBCs) was increased in animals treated with COC. Moreover, treatment with COC alone increased serum interleukin-10 (IL-10) concentration; however, it did not affect serum interferon gamma (INF-γ) concentration. Spleen histology showed hyperplasia of white pulp whereas thymus gland demonstrated mild cortical degeneration. On the other hand, KET treatment did not produce any significant change of any of these parameters. However, when coadministered with COC, significant reduction of bodyweight, spleen/bodyweight, and thymus/bodyweight ratios with degeneration of splenic white pulp and thymic cortex occurred. Moreover, the primary immunoglobulin response to SRBC and serum IL-10 concentration were decreased without significant change in serum IFN-γ or circulating leukocytic counts. COC caused a significant increase in serum corticosterone concentration that KET effectively prevented. On the other hand, a significant increase in plasma and tissue concentrations of norcocaine (NC) resulted following KET and COC administration in combination. Daily SKF-525A pretreatment at a dose of 30 mg/kg, IP, for 7 days 1 hour prior to KET and COC in combination effectively reversed the effects of this combination on body weight, organ/bodyweight ratios, histopathology, and serum Ig M and IL-10 concentrations without affecting leukocytic counts. On the other hand, SKF-525A pretreatment did not change the immunomodulatory effects of COC compared to non-pretreated animals. The results suggest that COC-induced immunomodulation most likely occurred through neuroendocrinal mechanisms. On the other hand, enhanced oxidative metabolism of COC in the presence of KET-induced immunosuppression.

Leptin and the post-operative inflammatory response. More insights into the correlation with the clinical course and glucocorticoid administration

BACKGROUND

Cardiac surgery involving cardiopulmonary bypass (CPB) causes a systemic inflammatory process which can lead to multiple organ failure and postoperative morbidity. Recent animal and human studies suggested a possible involvement of leptin in the systemic inflammatory response.

AIM

To characterize the response of leptin to open heart surgery (OHS) and the relationship between the time course of leptin levels and the post-operative clinical course, and to examine the effect of exogenous glucocorticoids.

PATIENTS AND METHODS

Forty-seven pediatric patients, undergoing OHS for congenital heart disease were studied. Thirty-four patients (Group 1) received methylprednisolone during CPB while 13 (group 2) did not. Serial blood samples were collected perioperatively and up to 24 h after surgery, and assayed for leptin and cortisol.

RESULTS

All patients' leptin levels decreased significantly during CPB (to 44-48% of baseline, p<0.001); they then increased, peaking at 12 h post-operatively. The levels of groups 1 and 2 were similar up to 8 h post-operatively; thereafter, those of group 1 were significantly higher. Recovery of leptin levels in patients with a more complicated post-operative course was comparatively slower. Cortisol levels of all patients increased significantly during CPB (p<0.001), gradually decreasing afterwards. Cortisol and leptin levels were inversely correlated in both patients' groups.

CONCLUSIONS

CPB is associated with acute changes in circulating leptin levels. A complicated postoperative course is associated with lower leptin levels which are inversely correlated with cortisol levels. Leptin may participate in post-CPB inflammatory and hemodynamic responses.

In vivo microdialysis sampling of cytokines produced in mice given bacterial lipopolysaccharide

Cytokines are proteins that mediate communication between cells of the immune system as well as certain other non-immune host cells. These proteins are produced by many cell types and they mediate immune and inflammatory responses. However, the direct site analysis of these critical proteins is hampered by the lack of site-specific tools available for such direct measurements. In this study, both in vitro and in vivo microdialysis sampling of different cytokines (tumor necrosis factor-alpha [TNF-alpha], interferon-gamma [IFN-gamma], interleukin-6 [IL-6], IL-12p70, and macrophage chemoattractant protein-1 [MCP-1]) was performed. A mouse model of bacterial lipopolysaccharide (LPS) administration and response pattern was used for in vivo studies. Three cytokines, TNF-alpha, IL-6, and MCP-1 were quantified in the serum from mice given LPS. In vivo studies demonstrated the ability to monitor increasing levels of these cytokines (TNF-alpha, IL-6, and MCP-1) via microdialysis probes placed in the peritoneal cavity of mice given LPS. All three cytokines were quantified simultaneously in 15 muL of dialysate using a multiplexed bead-based immunoassay for flow cytometry. The detected dialysate cytokine concentrations varied between 200 pg/mL and 1500 pg/mL for TNF-alpha, between 600 pg/mL and 3000 pg/mL for MCP-1, and between 2700 pg/mL and more than 5000 pg/mL for IL-6. The detected serum cytokine concentrations ranged from 5700 pg/mL to 35,000 pg/mL for TNF-alpha, from 40,000 pg/mL to 65,000 pg/mL for MCP-1, and greater than than 100,000 pg/mL for IL-6. This work demonstrates that microdialysis sampling can be used in vivo to collect temporal profiles of cytokine production.

Bartonella quintana lipopolysaccharide effects on leukocytes, CXC chemokines and apoptosis: a study on the human whole blood and a rat model

Bartonella quintana, an emerging gram-negative pathogen, may cause trench fever, endocarditis, cerebral abscess and bacillary angiomatosis usually with the absence of septic shock in humans. B. quintana lipopolysaccharide (LPS), a deep rough endotoxin with strong reactivity in the limulus amebocyte lysate (LAL)-assay, was studied in human whole blood and in a rat model. A significant (P<0.05) increase of interleukin-8 (IL-8) concentration, comparable to the level induced by enterobacterial LPS, was stimulated in the human whole blood by B. quintana LPS. Isolated human neutrophils delayed their apoptotic behavior in the presence of B. quintana LPS. In the rat, B. quintana LPS induced a significant (P<0.001) increase in white blood cell count, both 30 and 60 min after intravenous injection. Such leukocytosis was inhibited by pretreatment with prazosin, an alpha-adrenergic antagonist. B. quintana LPS did not significantly change heart rate (HR), hematocrit (HCT) and platelet count in the above reported in vivo model, and regarding mean blood pressure (MAP) only a very early (5 min after LPS) and mild (yet significant) hypotension was observed. In contrast, a long-lasting decrease of MAP was found in Salmonella minnesota R595 LPS-treated animals. Blood TNFalpha levels did not change significantly from the baseline in rats injected with either saline or with B. quintana LPS, on the contrary S. minnesota R595 LPS-injected animals showed substantial increase of TNFalpha levels up to 2924 pg/ml at 60 min after LPS injection. B. quintana LPS as well as Salmonella LPS-injected rats exhibited an increase of the blood levels of GRO/CINC-1, particularly at 240 min after LPS administration. Apical part of rat gut villi showed several TUNEL-positive cells in tissue sections from B. quintana LPS-treated animals. Taken together, our data demonstrates that B. quintana LPS is able to selectively stimulate some inflammatory mediators. B. quintana LPS-induced leukocytosis appears mediated by an alpha-adrenergic receptor. The delayed apoptotic process of leukocytes and the chemokine increase may explain the apoptotic cells found in the rat gut and the inflammatory reactions in some human Bartonella diseases. This peculiar inflammatory pattern induced by B. quintana LPS, may partially account for the lack of severe septic shock, observed in human B. quintana infections.

Effect of extracellular volume expansion and surgical stress on splanchnic blood flow and cardiac output in anesthetized rats: role of nitric oxide

In a normal volume state, surgical stress decreases rather than increases nitric oxide (NO) production in the vascular system. In our studies, the effect of minor and major surgical stress and three different degrees of volume expansion on systemic and splanchnic circulatory parameters and on the NO dependence of the circulation have been investigated. When the degree of volume expansion was increased, cardiac output and organ blood flow increased without significant change in vascular resistances. Major surgical stress reduced the increase in cardiac output and organ blood flow elicited by the volume expansion. NO synthase (NOS) inhibition significantly increased blood pressure and total peripheral resistance (TPR) and decreased cardiac output in all groups of animals. As the degree of volume expansion was increased, the NO dependence of the circulation in the surgically less- and more-stressed animals was inversely influenced in some cases. With the three degrees of volume expansion (20, 40, and 60 ml/kg), the NOS inhibition increased the TPR from 30.7 R/kg +/- 1.90 to 73.6 R/kg +/- 5.00, from 20.7 R/kg +/- 1.43 to 66.7 R/kg +/- 3.88, and from 19.9 R/kg +/- 1.25 to 49.1 R/kg +/- 3.84 in the surgically less-stressed animals and from 38.6 R/kg +/- 2.14 to 59.8 R/kg +/- 5.62, from 31.9 R/kg +/- 2.70 to 81.7 R/kg +/- 9.89, and from 29.1 R/kg +/- 2.49 to 91.1 R/kg +/- 6.36 in the surgically more-stressed animals. Volume expansion increases the NO dependence of the vascular resistance in the surgically more-stressed animals but decreases it in the surgically less-stressed animals.

Resting and circadian release of nitric oxide is controlled by leptin in male rats

Because leptin stimulates nitric oxide (NO) release from the hypothalamus and anterior pituitary gland, we hypothesized that it also might release NO from adipocytes, the principal source of leptin. Consequently, plasma concentrations of leptin and NO, estimated from its metabolites NO(3) and NO(2) (NO(3)-NO(2)), were measured in adult male rats. There was a linear increase of both leptin and NO(3)-NO(2) with body weight that was associated with a parallel rise in fat mass. These findings indicate that release of leptin and NO is directly related to adipocyte mass. Furthermore, there was a parallelism in circadian rhythm of both substances, with peaks at 0130 h and nadirs at 0730 h. Measurement of both leptin and NO(3)-NO(2) in plasma from individual rats revealed that NO(3)-NO(2) increased linearly with leptin. Incubation of epididymal fat pads with leptin or its i.v. injection in conscious rats increased NO(3)-NO(2) release. The release of NO(3)-NO(2) in vivo and in vitro exceeded that of leptin by many fold, indicating that leptin activates NO synthase. Leptin increased tumor necrosis factor (TNF)-alpha release at a 100-fold lower dose than required for NO release in vitro and in vivo, suggesting that it also may participate in leptin-induced NO release. However, because many molecules of leptin were required to release a molecule of TNF-alpha in vivo and in vitro, we believe that leptin-induced TNF-alpha release is an associated phenomenon not involved in NO production. The results support the hypothesis that adipocytes play a major role in NO release by activating NO synthase in the adipocytes and the adjacent capillary endothelium.

Lipopolysaccharide-induced leptin release is neurally controlled

Our hypothesis is that leptin release is controlled neurohormonally. Conscious, male rats bearing indwelling, external, jugular catheters were injected with the test drug or 0.9% NaCl (saline), and blood samples were drawn thereafter to measure plasma leptin. Anesthesia decreased plasma leptin concentrations within 10 min to a minimum at 120 min, followed by a rebound at 360 min. Administration (i.v.) of lipopolysaccharide (LPS) increased plasma leptin to almost twice baseline by 120 min, and it remained on a plateau for 360 min, accompanied by increased adipocyte leptin mRNA. Anesthesia largely blunted the LPS-induced leptin release at 120 min. Isoproterenol (beta-adrenergic agonist) failed to alter plasma leptin but reduced LPS-induced leptin release significantly. Propranolol (beta-receptor antagonist) produced a significant increase in plasma leptin but had no effect on the response to LPS. Phentolamine (alpha-adrenergic receptor blocker) not only increased plasma leptin (P < 0.001), but also augmented the LPS-induced increase (P < 0.001). alpha-Bromoergocryptine (dopaminergic-2 receptor agonist) decreased plasma leptin (P < 0.01) and blunted the LPS-induced rise in plasma leptin release (P < 0.001). We conclude that leptin is at least in part controlled neurally because anesthesia decreased plasma leptin and blocked its response to LPS. The findings that phentolamine and propranolol increased plasma leptin concentrations suggest that leptin release is inhibited by the sympathetic nervous system mediated principally by alpha-adrenergic receptors because phentolamine, but not propranolol, augmented the response to LPS. Because alpha-bromoergocryptine decreased basal and LPS-induced leptin release, dopaminergic neurons may inhibit basal and LPS-induced leptin release by suppression of release of prolactin from the adenohypophysis.