Effects of gypenosides on mouse splenic lymphocyte transformation and DNA polymerase II activity in vitro

AIM: To study the effects of gypenosides (Gyp) on lymphocyte transformation and DNA polymerase II activity. METHODS: Lymphocyte transformation response was induced by concanavalin A and lipopolysaccharides respectively. The activity of DNA polymerase II and DNA synthesis were assayed with TTP and [3H]TdR incorporation respectively in mixed lymphocyte culture test. RESULTS: Gyp 2.5-20 mg L-1 enhanced splenic T- and B- cell transformation, increased the DNA synthesis and potentiated the activity of DNA polymerase II. However, Gyp > 40 mg L-1 showed contrary effects. CONCLUSION: Gyp regulated lymphocyte transformation and DNA synthesis by regulating DNA polymerase II activity.     

Developmental differences in rats of suppressive effects of extinction as a function of extinction sessions.

Used 1 or 2 extinction sessions, 2 extinction procedures, and 2 ages of rats (23 and 95-120 days old) in a developmental analysis of the effects of extinction. Ss were 96 male Long-Evans hooded rats. The apparatus was a Y maze with 3 discriminably different arms. After 10 sessions of positive reinforcement, Ss received either 1 or 2 extinction sessions in which responding in 1 arm was no longer reinforced. Following extinction, responding in all 3 arms was again reinforced. Recovery data show that (a) the suppressive effects of extinction were greater for adults than infants and (b) the 2nd extinction session had a greater impact on the adults. Results support the hypothesis that younger rats have greater difficulty than older ones in inhibiting a response. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental differences in the suppressive effects of punishment.

Used 3 levels of shock intensity (1, 2, or 3 ma.), 3 test delay periods (0, 5, or 25 days), and 25- and 100-day-old male Long-Evans hooded rats (N = 104) in a study of developmental differences in recovery from the suppressive effects of punishment. The apparatus was a Y maze with 3 discriminably different arms. After 10-14 sessions of positive reinforcement, Ss were shocked for 2 sessions each time they responded in 1 arm. Following these shock sessions, a delay was given prior to the recovery sessions. Results from the shock days indicate that the number of shocks to suppression was a function of age, intensity, and shock days. The recovery data showed that (a) recovery was an inverse function of intensity, (b) the suppressive effects of punishment were much greater for the adults than the infants at all intensities, and (c) recovery was not a function of delay periods. Results support the hypothesis that younger organisms have greater difficulty than older ones in inhibiting a response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Suppression of splenic T lymphocyte proliferation by acute cocaine administration

We have recently demonstrated that cocaine administration has a limited effect on mitogen-stimulated T lymphocyte proliferation. The present study investigated the effect of cocaine on splenic T cell response to alloantigens. Rats received intraperitoneal injections of cocaine HCI, and splenocytes were isolated either thirty minutes or three hours post-administration. In the thirty minute exposure group, cocaine at 10.0 and 25.0 mg/Kg/B.Wt. suppressed (p<0.05) T cell proliferation in mixed lymphocyte cultures. Compared to control data, proliferation was decreased by 46.6% and 56.4%, respectively. However, this effect was not as pronounced in cells isolated three hours post-administration, indicating a transient inhibition of T cell function by cocaine. The decrease in splenic T cell proliferation in response to alloantigens in the thirty minute exposure group did not reflect alterations in calcium influx or IL-2 production. Although this study did not ascertain the exact mechanism of inhibition, these results demonstrate that short-term cocaine exposure can alter T cell reactivity to alloantigens, suggesting a reduction in the functional status of these cells.     

Dual effects of tetrachlorvinphos on procaine toxicity and procainesterase activity in rats

The effect of tetrachlorvinphos (TCVP) on liver procainesterase (PROCase) and procaine toxicity was studied in rats. TCVP is an organophosphate with an inducible effect on drug metabolizing enzymes. A single oral dose of 500 mg/kg of TCVP caused a remarkable decrease in PROCase (40% of control) 24 hr later and increased the motality after injection of procaine (250 mg/kg, i.p.) from 54% to 87%. Conversely, it was observed that PROCase elevated to 140% of the control and mortality decreased from 54% to 25% on day 3. With repeated administration of TCVP (500 mg/kg/day) for 5 days, the PROCase activity that was inhibited on day 1 was gradually restored to normal levels by 5 days and the mortality altered to 25%. The inducible effect on PROCase was examined using desmethyl-TCVP, a metabolite of TCVP without inhibitory effect on the enzyme; PROCase activity was enhanced to 1.6-fold of the control and procaine concentration in the brain was reduced to 30% of the control, accompanied with no death of rats after procaine injection. Electrophoresis of the solubilized liver microsomal fraction confirmed the inducible effect of TCVP on PROCase; microsomal protein from the TCVP-treated rat was more deeply stained than that from the control, and the PROCase activity of two anodic bands increased in the TCVP-treated microsomes. These results indicate that TCVP has a dual action on PROCase, inducible and inhibitory, and that the direct inhibitory effect of TCVP might mask the increased amount of the enzyme induced by repeated administration of TCVP. The dual effect of TCVP on PROCase would cause the change in procaine toxicity.     

Enhancing versus suppressive effects of stress hormones on skin immune function

Delayed-type hypersensitivity (DTH) reactions are antigen-specific cell-mediated immune responses that, depending on the antigen, mediate beneficial (e.g., resistance to viruses, bacteria, and fungi) or harmful (e.g., allergic dermatitis and autoimmunity) aspects of immune function. Contrary to the idea that stress suppresses immunity, we have reported that short-duration stressors significantly enhance skin DTH and that a stress-induced trafficking of leukocytes to the skin may mediate this immunoenhancement. Here, we identify the hormonal mediators of a stress-induced enhancement of skin immunity. Adrenalectomy, which eliminates the glucocorticoid and epinephrine stress response, eliminated the stress-induced enhancement of skin DTH. Low-dose corticosterone or epinephrine administration significantly enhanced skin DTH and produced a significant increase in the number of T cells in lymph nodes draining the site of the DTH reaction. In contrast, high-dose corticosterone, chronic corticosterone, or low-dose dexamethasone administration significantly suppressed skin DTH. These results suggest a role for adrenal stress hormones as endogenous immunoenhancing agents. These results also show that hormones released during an acute stress response may help prepare the immune system for potential challenges (e.g., wounding or infection) for which stress perception by the brain may serve as an early warning signal.     

The effects of morphine, nicotine and epibatidine on lymphocyte activity and hypothalamic-pituitary-adrenal axis responses

Acute administration of morphine alters various neuroendocrine and immune parameters via opioid receptors located within the central nervous system. Similar effects have been reported after systemic nicotine treatment. To examine the possible relationship between opioid and nicotinic receptor activation on the immune system, we compared the effects of morphine with both nicotine and the highly selective nicotinic agonist, epibatidine. Male Sprague-Dawley rats were treated with either morphine (10 mg/kg, s.c.), nicotine (2.85 mg/kg, s.c. = 1 mg/kg freebase), or epibatidine (5 microg/kg, s.c.) and sacrificed 2 hours later. Each drug increased plasma corticosterone levels and decreased the magnitude of the peripheral blood lymphocyte proliferation response to the T cell mitogen concanavalin A. None of the treatments had a significant effect on splenic or thymic lymphocyte responses. The effects of nicotine treatment were dose-dependent. Pretreatment with the quaternary ganglionic antagonist chlorisondamine (0.5 mg/kg, i.p.), completely blocked the effect of epibatidine on blood lymphocytes without altering the elevation of corticosterone levels. Although naltrexone (10 mg/kg, s.c.) blocked all effects of morphine, the effects of epibatidine were not blocked by the opioid receptor antagonist. Furthermore, in contrast to morphine (), central injection of neither nicotine (30 or 240 nmol) nor epibatidine (5, 50, or 500 ng) altered blood lymphocyte responses. These results suggest that, like morphine, nicotinic agonists decrease blood lymphocyte proliferation responses, apparently independent of elevated corticosterone. However, unlike morphine, nicotinic agonists appear to act predominantly at peripheral receptors, suggesting that nicotinic receptors are downstream of opioid receptors in a centrally mediated opioid-induced immunomodulatory pathway.     

Time-dependent effects of Klebsiella pneumoniae endotoxin on hepatic drug-metabolizing enzyme activity in rats

The time-dependent effects of Klebsiella pneumoniae endotoxin on hepatic cytochrome P450-dependent drug-metabolizing capacity (cytochrome P450 and b5 content, activity of aminopyrine N-demethylase, p-nitroanisole O-demethylase, aniline hydroxylase and benzphetamine N-demethylase) and on the pharmacokinetics of antipyrine have been determined in rats. Measurement of enzyme activity and antipyrine (after intravenous injection of 20 mg kg(-1)) were performed 2, 24 and 96 h after a single intraperitoneal injection of endotoxin (1 mg kg(-1)) and after repeated doses (once daily for 4 days). The contribution of tumour necrosis factor alpha (TNFalpha) to the endotoxin-induced changes was also examined in rats pretreated with granulocyte colony-stimulating factor (G-CSF). The systemic clearance of antipyrine and the activity of hepatic cytochrome P450-dependent drug-metabolizing enzymes were dramatically reduced 24 h after a single injection of endotoxin, but had returned to control levels by 96h. The magnitudes of these decreases in these measurements after repeated doses of endotoxin were similar to those seen 24h after the single dose. The systemic clearance of antipyrine correlated significantly with cytochrome P450 content and aminopyrine N-demethylase activity. In histopathological experiments, moderate hypertrophy of Kupffer cells was observed, with no evidence of severe liver-tissue damage. G-CSF pretreatment suppressed the increased plasma concentrations of TNFalpha produced 2 h after single endotoxin injection, but did not eliminate the endotoxin-induced decrease in the systemic clearance of antipyrine, suggesting that TNFalpha is not the sole component responsible for the reduction of cytochrome P450-mediated drug-metabolizing enzyme activity. These results provide evidence that a single intraperitoneal injection of 1.0 mgkg(-1)K. pneumoniae endotoxin in rats reduces hepatic P450 and b5 levels, and reduces the activity of various cytochrome P450-mediated drug-metabolizing enzymes without causing severe liver-tissue damage. This suggests that the effect of endotoxin on hepatic cytochrome P450-mediated drug-metabolizing isozymes is non-selective.     

Analysis of splenic and thymic lymphocyte subpopulations in chickens infected with Salmonella enteritidis

Lymphocytes expressing CD3, CD4, CD8, pan lymphocyte, IgA, IgG and IgM cell surface antigens were assessed by in the spleen and thymus of chickens following infection with Salmonella enteritidis using flow cytometric analysis. At 6 days post primary infection and 2 days post secondary infection with S. enteritidis, the percentages of IgA+ and IgM+ lymphocytes in the spleen were significantly increased (P < 0.05). At 2 days post secondary infection with S. enteritidis, the percentage of CD4+ T lymphocyte in the spleen and CD8+ T lymphocyte percentage in the thymus were significantly increased (P < 0.05). These results indicate that S. enteritidis infection induces changes in the spleen and thymus that reflect the dynamics of the host protective immune response.     

Facilitative and suppressive effects of punishment on species-typical aggressive display in Betta splendens.

Determined effects of moderate and intense punishment on aggressive behavior. Following either 15 or 45 massed presentations to a mirror, 35 Siamese fighting fish were punished for aggressive display (gill extension). Intense shock punishment led to complete suppression of the display. Recovery of the display depended on the level of habituation, i.e., only the fish given 15 mirror presentations prior to punishment showed recovery. Given "room" for an increase, a moderate level of punishment led to longer displays. A 2nd experiment with 6 Ss confirmed this latter finding with spaced (daily) blocks of trials. (23 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chronic morphine treatment exaggerates the suppressive effects of sucrose and cocaine, but not lithium chloride, on saccharin intake in Sprague-Dawley rats.

Three experiments examined the effect of chronic morphine treatment on cocaine-, sucrose-, and lithium chloride (LiCl)-induced suppression of saccharin intake in Sprague-Dawley rats. All rats were either water- or food-deprived and then implanted subcutaneously with 1 morphine (75 mg) or vehicle pellet for 5 days. They were then given brief access to 0.15% saccharin and soon thereafter injected with either cocaine (10 mg/kg sc) LiCl (0.009 M, 1.33 ml/100 g body weight ip), or saline, or in Exp 2, given a 2nd access period to either a preferred 1.0 M sucrose solution ot the same 0.15% saccharin solution. There was 1 taste–drug or taste–taste paring per day for a number of days. The results showed that a history of chronic morphine treatment exaggerated the suppressive effects of a rewarding sucrose solution and cocaine but not those of the aversive agent, LiCl. These data provide further support for the reward compairison hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning and tolerance to the intake suppressive effect of cholecystokinin in rats.

Experiments were conducted to evaluate the contribution of conditioning to tolerance to the meal suppressive effect of cholecystokinin (CCK). The results indicate that (1) tolerance was contingent (the rat had to eat in conjunction with drug administration for tolerance to the meal suppressive effect to develop), (2) tolerance was displayed only in the context of environmental cues previously associated with CCK, (3) CCK-tolerant rats overate when presented with cues previously associated with the peptide, and (4) CCK tolerance displayed latent inhibition. The results are consistent with C. X. Poulos and H. Cappell's (1991) homeostatic theory of tolerance, as well as with the results of other experiments indicating that conditioning contributes to tolerance to many effects of a variety of drugs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

'Long-distance' lymphocyte study. The effects of transporting blood in lymphocyte blastogenic responses

A comparison of blastogenic responsiveness to antigens and mitogen by human lymphocytes was made between cells which had been processed for culture immediately following blood collection and cells obtained from blood collected 9-11 hr previously and transported via commercial airline from the patients' homes to our laboratory. There were no significant differences in the responses of transported and non-transported cells if the blood was maintained at ambient temperature during the period of shipment. Chilling the blood during transport, however, resulted both in decreased stimulation of the cells and increased 'background' activity in unstimulated cultures. These findings indicate the feasibility of carrying out both limited immunological evaluations and extended periods of follow-up for patients located at considerable distances from a research laboratory.     

Human transfer factor: effects on lymphocyte transformation

Transfer factor preparations from 57 different donors have been compared for effects on mitogen- and antigen-induced lymphocyte transformation. Nine of the preparations were mitogenic when added to cultured lymphocytes although the magnitude of this activity was relatively low. The majority of the preparations (48/57) did not affect PHA-induced lymphocyte transformation although augmentation (6 of 57) and suppression (3 of 57) was observed with some. In addition we observed that most of the preparations tested suppressed ConA stimulation and augmented the PWM response. When selected preparations were evaluated on antigen-responsive cells, there was a correlation between the magnitude of antigen responsiveness and the magnitude of TF augmentation of antigen-induced lymphocyte transformation (p less than 0.005). Cultures that were not responsive to antigen (KLH-negative or BUdR-treated) could not be stimulated by TF from immune donors and antigen. These data suggest that TF preparations contain either stimulatory or inhibitory components and that TF is not capable of activating naive lymphocytes to undergo transformation in response to antigen.     

Combined effects of hypokinesia and various doses of gamma irradiation on conditioned reflex activity in rats

There has been studied the effect of 30-day hypokinesia (HK) and gamma-radiation at three non-lethal doses (3.5, 5.0, and 8.5 Gy) on elaboration of the motor-defence reflex of active avoidance (RAA). Radiation-induced slowing-down of the RAA formation was in direct proportion to the dose applied. Modifying action of gamma-radiation on the hypokinesia effect showed up markedly only at the highest dose (8.5 Gy). Modifying action of HK with respect to the radiation effect can be assessed as insignificant; however, a downward trend was established in the rate of the reflex formation under the combined exposure to these factors.     

Potent antileukemic activity of the novel agents norsegoline and dibezine

We examined the effect of norsegoline, a natural marine product, and dibezine, a synthetic product, on the survival of human myeloid progenitor cells [colony-forming unit-cells (CFU-C)] from normal individuals and from 10 patients with Philadelphia-positive chronic myelogenous leukemia (CML) in chronic phase and blastic crisis. We compared their effect to the effect of IFN-alpha. Norsegoline, dibezine, and IFN-alpha inhibited the proliferation of CFU-C in a dose-dependent manner. The number of CFU-C from bone marrow (BM) of five CML patients in chronic phase exposed for 16 h to norsegoline (10(-8)-10(-6)M), dibezine (10(-8)-10(-6)M), and IFN-alpha (500 units/ml) was found to be statistically lower (P < 0.05) than the number of CFU-C derived from normal individuals. A 16-h drug exposure of CD34(+) cells isolated from the peripheral blood of three CML patients in blastic crisis and from BM of two patients in chronic phase resulted in a marked inhibition in the ability of the cells to proliferate in liquid culture and a reduction in CFU-C content. Using the fluorescent in situ hybridization technique, we evaluated detection of the BCR/ABL fusion product in the CD34(+) cells. All five patients were 100% Philadelphia positive at diagnosis. BCR/ABL translocations were detected in 94.6 +/- 0.6% of cells following their growth in liquid culture for 7 days. Following exposure of CD34(+) cells to norsegoline, dibezine, or IFN-alpha, BCR/ABL fusion signals could be detected in 73 +/- 11%, 66.5 +/- 4. 7%, and 66.0 +/- 2.5% of cells from BM and 72.3 +/- 5%, 68.8 +/- 7%, and 60.6 +/- 6.8% of peripheral blood, respectively. Our data indicate that norsegoline and dibezine have in vitro an antileukemic effect against Philadelphia-positive cells and may be used in conjunction with currently available agents for ex vivo purging of BM and/or peripheral blood of CML patients in conjunction with autologous bone marrow transplantation.     

Maternal behavior in male rats: critical times for the suppressive action of androgens

The immediate and carry-over effects of scopolamine and d-amphetamine were evaluated in a free running Y-maze spontaneous alternation task. The immediate effect of scopolamine (1.0 mg/kg) or d-amphetamine (5.0 mg/kg) was to reduce alternation to chance or to levels significantly below chance (perseveration), respectively. On a second, non-drug test day alteration decreased in saline treated animals, but increased among mice which received scopolamine on Day 1. In contrast, upon retesting in the non-drug state, the performance of animals initially treated with d-amphetamine resembled that of saline treated mice. Subsequent experiments revealed that these effects could not be attributed to drug effects on peripheral mechanisms, consolidation, residual drug action or drug dissociated learning. It was concluded that the behavioral effects of scopolamine and d-amphetamine are qualitatively different. Whereas scopolamine disrupts habituation, d-amphetamine induces perseveration independently of any effects on habituation.     

Differential activity of P-glycoprotein in normal blood lymphocyte subsets

To better understand the phenomenon of P-glycoprotein (P-170) expression we investigated lymphocyte subpopulations for P-170 function in healthy volunteers. Studies were based on three-colour flow cytometry including the fluorescent probe rhodamine 123 (Rh123), which is transported by P-170. Marked Rh123 efflux was detected in CD8+ T lymphocytes with CD8+/CD45RA+ T cells (naive cells) showing significantly higher P-170 activity as compared with CD8+/CD45RA- cells (P<0.04). Vice versa, CD8+/CD45RO+ T cells (memory cells) demonstrated less P-170 activity than CD8+/CD45RO- cells (P<0.04). P-170 function was less prominent in CD4+ T cells, however, Rh123 efflux was higher in the CD4+/CD45RA+ and CD4+/CD45RO- subpopulations (P<0.025) corresponding to the CD8+ results. Dye efflux differed significantly between activated and non-activated CD8+ and CD4+ as well as CD8+/CD11b+ and CD8+/CD11b- T lymphocytes. Since CD16+ natural killer cells (NK) expressed the highest level of P-170, the NK cytotoxicity against 51Cr-labelled K562 target cells was assayed in the presence or absence of P-170 inhibitors. NK related cytotoxicity was significantly reduced in the presence of R-verapamil and dexnigaldipine-HCP in a dose-dependent manner. The differential expression of P-170 activity in naive and memory T cells together with the reduced NK related cytotoxicity in the presence of MDR-modulators suggest a physiological role of P-170 in immunological functions of these lymphocyte subsets. Consequently, the addition of MDR modulators to conventional chemotherapy as a strategy to overcome drug resistance should consider possible adverse immunosuppressive effects.