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Effects of amphetamine on NK-related cytotoxicity in rats differing in locomotor reactivity and social position

The effect of i.p. administration of 1mg/kg of amphetamine (AMPH) on natural killer cells cytotoxicity (NKCC) and number of large granular lymphocytes (LGL-NK) together with plasma corticosterone (CORT) level and WBC was evaluated in male Wistar rats differing in two behavioral features: locomotor reactivity to novelty (high, HR and low, LR responders) and social position (dominants, D and subordinates, S). In the majority of animals AMPH evoked (30 min after administration) an increase in NKCC and LGL (NK) number accompanied by lymphopenia, neutrocytosis, monocytosis, and an increase in CORT level. Changes in NKCC (LU20) showed substantial individual variability: in HR group approximately 513Delta%, p <0.01 (relative to the control); LR group approximately 56Delta%, p >.05; D group approximately 441Delta%, p >0.001; S group approximately 216Delta%, p >0.05; HR/D group approximately 643Delta%, p <.001; HR/S group approximately 414Delta%, p <.001; LR/D group approximately 191Delta%, p >.05; and LR/S group approximately -19Delta%, p .05. The increase in CORT level, lymphopenia, and neutrocytosis indicated a stress-like reaction to AMPH. No significant correlation between NKCC and CORT level was found. The results obtained indicate that AMPH can evoke an increase in NK-related cytotoxic activity quantitatively related to high behavioral reactivity to novelty and social dominance, however NKCC is not related to the AMPH-induced CORT changes.

Small doses of morphine can enhance NK cell cytotoxicity in pigs.

The effect of small and moderate doses of morphine (MF) on NK cell lytic activity (cytotoxicity, NKCC) ((51)Cr release test) and the number of circulating large granular lymphocytes (LGL) was evaluated in i.v. catheterized Pietrain crossbred pigs. Simultaneously, plasma cortisol (COR) (RIA method) was measured. Blood samples were collected 15, 60, 120, 180, and 240 min after i.v. injections of 0.5, 1.0 and 5.0 mg/kg of MF alone or MF pretreated with naloxone (NX, 1.0 mg/kg, i.v., 15 min before MF). It was found that MF induced dose- and time-dependent changes of NKCC. MF in a dose of 0.5 mg/kg evoked 4-fold increase in NKCC (in comparison to saline) without changes in the number of LGL/NK cells. Higher MF doses (1.0, 5.0 mg/kg) induced an early increase (up to 300Delta% and 29Delta%, respectively) followed by a decrease in cytotoxicity (to -76Delta% after 5.0 mg/kg), and in LGL number (-36Delta% after 5.0 mg/kg). These effects were concomitant with a marked rise in plasma COR (up to 234Delta% after 0.5 mg/kg and 567Delta% after 5.0 mg/kg of MF). NX pretreatment blocked all the changes in cytotoxicity but not in the LGL cell number and COR concentrations. The results indicate that MF, besides having well known immunosuppressive effects, can also enhance NKCC through the opioid receptors-dependent manner. The enhancement of cytotoxicity appears as a purely functional change independent of the recirculation of NK cells which occurs despite the high plasma concentrations of COR.

Restraint effects on stress-related hormones and blood natural killer cell cytotoxicity in pigs with a mutated ryanodine receptor

A mutation in the ryanodine receptor gene (RYR1) of the calcium release channel is responsible for increased stress susceptibility in pigs. In the present study, the relation of a mutation in RYR1 with the neuroendocrine (stress-related hormone) response and the immune defense represented by natural killer cell cytotoxicity (NKCC) during a 4-h restraint and recovery phase in 60 male pigs was investigated. Blood samples were collected from pigs previously divided into RYR1 genotypes (nn, Nn, NN), based on PCR amplification and restriction analyses. The blood samples collected during the restraint and recovery phases of the experiment were used to determine NKCC ((51)Cr-release assay), large granular lymphocyte number (hematologic method), and plasma concentrations of prolactin (PRL), GH, ACTH, and cortisol (COR) (by specific RIA). The greatest degree of NKCC response (P < 0.05) to restraint stress relative to controls was observed for the stress-susceptible homozygote group (nn). Measures of stress-related hormones were positively correlated with NKCC during the entire experimental period (P < 0.001 for all investigated hormones) in the nn group. Immunostimulatory effects in the early (0-60 min) phase of restraint were associated with increased hormone responses, especially PRL and GH. In the late (180-240 min) phase of stress and the recovery phase (480 min), a decrease in immune response was accompanied by an elevated COR response in all RYR1 genotypes. Moreover, divergent responses of both PRL (greatest in nn, P < 0.001) and GH (greatest in NN, P < 0.001) to the 4-h restraint were observed. Our results suggest that stress-susceptible RYR1-mutated homozygotes develop a greater level of immune defense, including cytotoxic activity of NK cells, and accompanied by more pronounced stress-induced changes in neuroendocrine response than stress-resistant heterozygous (Nn) and homozygous (NN) pigs.

Natural killer cell cytotoxicity, cytokine and neuroendocrine responses to opioid receptor blockade during prolonged restraint in pigs

This study evaluated porcine natural killer cell cytotoxicity (NKCC), plasma cytokines including interleukin (IL) 1β, IL-6, IL-10, IL-12 and tumor necrosis factor-α and plasma stress-related hormones including prolactin (PRL), growth hormone (GH), β-endorphin (BEND), ACTH and cortisol (COR) during a 4h restraint and recovery phase after saline or naloxone (1mg/kg BW) administration. The restraint preceded with saline altered NKCC and IL-12 concentration (an early from 15 to 60 min increase followed by a decrease) and increased other measured cytokines and hormones concentrations. Naloxone pretreatment blocked the suppressive effects of the restraint on NKCC and IL-12 and altered IL-10, IL-6, TNF-α, PRL and ACTH concentrations. Furthermore, in naloxone-injected pigs, a positive correlation was found between NKCC and all measured cytokines (with the exception of IL-6) and BEND, ACTH and COR. Results suggest that naloxone-sensitive opioid pathways could influence the mechanisms underlying the immune system (including NKCC) response during stress.

Effects of chronic desipramine pretreatment on open field-induced suppression of blood natural killer cell activity and cytokine response depend on the rat's behavioral characteristics

Effects of 14 consecutive day exposure to desipramine (10mg/kg i.p.), by itself or following chronic open field (OF) exposure, on subsequent neuroimmunological effects of acute (30 min) OF stress and the involvement of individual differences in response to novelty or social position in the anti-depressive responsiveness were investigated. Chronic desipramine pretreatment did not protect against OF stress-induced suppression of blood anti-tumor natural killer cell activity but increased plasma interleukin-10 and decreased interferon-γ and corticosterone concentration. These effects were particularly dangerous for the animals with increased responsivity to stress (desipramine alone) or with low behavioral activity (desipramine after chronic stress).

Cocaine administration increases CD4/CD8 lymphocyte ratio in peripheral blood despite lymphopenia and elevated corticosterone

The CD4/CD8 lymphocyte ratio in peripheral blood is used in the diagnosis of HIV infection, autoimmune disorders or susceptibility to infections. The present experiment aimed to evaluate the lymphocyte subsets, their distribution and CD4/CD8 ratio in blood after repeated, intravenous administration of cocaine. Adult male Wistar rats received three daily, in 30 min intervals, intravenous infusions of cocaine hydrochloride (5 mg/kg) or saline for 14 consecutive days. After each infusion the locomotor-activating effects of cocaine were assessed. Blood samples were collected 30 min after the last daily infusion on the 1st, 7th and 14th day of treatment. Total leukocyte numbers, percentages of leukocyte subpopulations, and T, B, NK, T CD4+, and T CD8+ lymphocyte subsets, IFN-γ, and plasma corticosterone were determined. Repeated cocaine treatment resulted in an increase in neutrophil numbers and a significant decrease in total leukocyte and lymphocyte numbers involving a significant reduction in numbers of T, B, and NK lymphocyte subsets. T CD4+ and T CD8+ lymphocyte numbers were reduced but with a considerably smaller decrease in T CD4+ number. Cocaine treatment altered proportions between the lymphocyte subsets by decreasing the percentages of T CD8+, B, and NK cells but increasing a percentage of T CD4+ cells. Destabilization in proportions between T CD4+ and T CD8+ was manifested as an elevated CD4/CD8 ratio that occurred despite increased plasma corticosterone and the lymphocytopenia. Cocaine did not affect the concentration of IFN-γ. The results suggest that although cocaine induced lymphopenia, it did not suppress the overall immune activity in terms of the CD4/CD8 ratio.

Changes in blood CD4 + T and CD8 + T lymphocytes in stressed rats pretreated chronically with desipramine are more pronounced after chronic open field stress challenge

The present study examines the influence of a chronic (14 consecutive days) desipramine (10mg/kg i.p.) pretreatment by itself vs. after chronic (7 consecutive day) open-field (OF) on immune system alterations in response to acute (30 min) OF in Wistar rats (n=60). Opposing to the effect of desipramine injected alone, the combined pretreatment after chronic OF challenge exerts suppressive effects on peripheral blood T/B, CD4(+)T-helper/inducer and CD8(+)T-cytotoxic/suppressor but not NK cell number, decreased interferon-γ/interleukin-10 ratio and thymus weight in the stressed rats. It suggests that chronic stress exposure is important for the immunomodulatory effects of pretreatment with antidepressants.

The effects of ryanodine receptor 1 (RYR1) mutation on plasma cytokines and catecholamines during prolonged restraint in pigs.

In the current study, plasma cytokines, including interleukin (IL) 1, IL-2, IL-6, IL-10, IL-12, interferon-γ (IFN-γ) and tumor necrosis factor-α (TNF-α) and catecholamines (adrenaline and noradrenaline) were evaluated during 4h restraint and recovery phase in 60 male pigs. Blood samples were collected from three groups of pigs representing different RYR1 genotypes, namely NN homozygotes (wild-type), Nn heterozygous and nn homozygous (mutant). The 4h restraint evoked an increase in plasma cytokine concentrations in each of the RYR1 genotype groups. During the restraint, the greatest concentrations of plasma IL-6, IL-10, IL-12 and TNF-α in nn homozygous pigs and IFN-γ in NN homozygous were observed. Interleukin 1, IL-2, IL-10, and TNF-α measures were positively intercorrelated in each of the three RYR1 genotype group. A positive correlation was seen between all measured cytokines (with the exception of IL-6) and plasma catecholamine concentrations in Nn heterozygous and nn homozygous pigs. The results suggest that of the cytokine parameters evaluated, IL-6, IL-10, IL-12 and TNF-α of the nn homozygous group seem to show a stronger stress-related response as compared with those of the other two (NN and Nn) groups.

Chronic antidepressant desipramine treatment increases open field-induced brain expression and spleen production of interleukin 10 in rats

In the present study, we established a role of individual differences in locomotor response to novelty or social position in modulatory effect of chronic (14 consecutive days) antidepressant drug desipramine pretreatment (10mg/kg i.p.) on acute (30 min), white and illuminated open field (OF)-induced changes in spleen anti-tumor activity of natural killer (NK) cells (chromium release assay) in parallel to the brain anti-inflammatory interleukin 10 (IL-10) and Fos expression (immunohistochemistry), splenocytic pro-inflammatory interferon γ (IFN-γ) and IL-10 production (ELISA), and plasma corticosterone concentration (RIA) in rats. The involvement of individual differences (high (HR) and low (LR) responders to novelty or dominants (D) and subordinates (S)) in the anti-depressive responsiveness, was investigated in the desipramine treated by itself (DES) or following 7 consecutive days of OF exposure (ChS-DES) group. In the desipramine pretreated groups, OF stress decreased spleen NKCC, behavioral activity, the Con A-stimulated splenocyte IFN-γ response and plasma corticosterone concentration whereas it increased the brain and splenocyte IL-10 response. The percentage of OF-induced IL-10/Fos(+) cells was increased in the CA1 and dentate gyrus of the hippocampus and amygdaloid nucleus, particularly in the LR-D (DES) and LR-S (ChS-DES) rats. Moreover, a decreased splenocytic ability to produce IFN-γ and IL-10, particularly in the HR-S (DES) and LR-S (ChS-DES) rats, was noted. There were no significant differences in the OF-induced NKCC suppression between the behavioral groups. These studies emphasize that chronic desipramine pretreatment had anti-inflammatory but not immunoprotective properties against OF stress-induced neuroimmunological effects which depend on the animals behavioral characteristics and treatment.

Blood natural killer cell cytotoxicity enhancement correlates with an increased activity in brain motor structures following chronic stimulation of the bed nucleus of the stria terminalis in rats

The present study indicates that a chronic 14 day electrical stimulation of the bed nucleus of the stria terminalis (BST) increased blood but not spleen natural killer cell (NK) cytotoxicity and a large granular lymphocyte (LGL) number. These immune changes positively correlated with the increased activity in brain cortical and subcortical motor structures that influence the BST stimulation-induced behavioral response. No significant changes in blood and spleen leukocyte population numbers and plasma corticosterone concentration after the stimulation were found. The obtained results suggest that this immunoenhancing effect on blood NK cell function and number is dependent on the behavioral outcome of the BST stimulation rather than endocrine response.