Changes in rhythmicity of ambulatory and drinking activities produced by presentation of short time lightings during dark period in rats]

It is well known that the lighting conditions affect many physiological phenomenon of laboratory animals. However, lighting conditions are frequently disturbed by investigators themselves. In this study, behavioral (ambulation and drinking) rhythmicities of rats were investigated after irregular lighting; i. e. presentation of short time lighting at 21:00, 24:00 and 3:00 for 12 min during dark period (18:00-6:00). Vaginal smear was taken and sexual cycle was observed everyday. Ambulatory and drinking activities were measured by Gundai type Ambulo-drinkometer. The irregular lighting produced the following changes in the rhythmicities: 1) increase in the ambulatory activity during 15:00-18:00 immediately before dark period 2) decrease in ambulatory activity before ovulation 3) disappearance of inhibitory phenomenon of drinking activity which was usually observed before ovulation 4) increase in the drinking activity during 6:00-9:00 immediately after dark period 5) the changes in rhythmicities of the behavioral activities lasted for more than 1 month after replacement to the regular lighting condition.     

Changes in rhythmicity of ambulatory and drinking activities in immature female rats

Adult female rats showed increase in ambulatory activity and marked decrease in drinking behavior at early dark period (18:00-24:00) of proestrus stage before ovulation. In this study, we observed the changes in patterns of ambulatory and drinking activities of immature rats associated with estrous cycle during growing period. Immature female rats of the Wistar-Imamichi strain were used, and both behavioral activities were measured continuously, using Gundai type Ambulodrinkometer. From these observations, it was found that the typical patterns of ambulatory and drinking activities which were observed in adult female rats appeared at the sixth (51-60 days old) and the third (39-49 days old) estrous cycle, respectively.     

Liver nucleotides in acute experimental liver injury induced by dimethylnitrosamine and by thioacetamide

1. The concentrations of the nicotinamide-adenine dinucleotides in rat liver have been determined at intervals during the period 1-24hr. after feeding adult female rats with dimethylnitrosamine or thioacetamide. 2. The administration of dimethylnitrosamine resulted in a rapid decrease in the sum of NAD+NADH(2). This sum was decreased by 40% 3hr. after dosing. 3. Dimethylnitrosamine administration also produced an overall decrease in the NADP+NADPH(2) but this decrease was not so early nor as marked as that found for NAD+NADH(2). 4. The changes produced by thioacetamide were quite different from those obtained with dimethylnitrosamine. Thioacetamide produced a temporary rise in the NAD+NADH(2) followed by a small fall. The NADP+NADPH(2) was little changed in the early hours after dosing with thioacetamide but had decreased by approx. 15% 18hr. after administration. 5. These changes are discussed in terms of the known hepatotoxic actions of dimethylnitrosamine and thioacetamide, and are compared with previously reported changes found after the administration of carbon tetrachloride.     

Extrapyramidal and neuroendocrine effects of AM404, an inhibitor of the carrier-mediated transport of anandamide.

A selective inhibitor of the carrier-mediated transport of endogenous cannabinoids, N-(4-hydroxyphenyl)-arachidonylethanolamide (AM404), has been recently synthesized and proposed as a useful tool for studying the physiological effects of endogenous cannabinoids and as a potential therapeutic agent in a variety of diseases. In the present study, we have examined the effects of this compound in two important brain processes in which a role for anandamide and other endogenous cannabinoids has been claimed: neuroendocrine regulation and extrapyramidal motor activity. A single and well-characterized dose of AM404, which presumably resulted in a significant elevation of the levels of endogenous cannabinoids, produced a marked decrease in plasma prolactin (PRL) levels, with no changes in luteinizing hormone (LH) levels. This decrease in PRL levels was accompanied by an increase in the activity of tyrosine hydroxylase (TH) in the medial basal hypothalamus. Both decreased PRL secretion and increased hypothalamic TH activity have been reported to occur after the administration of anandamide. Administration of AM404 also produced a marked motor inhibition in the open-field test, as also reported for anandamide, with a decrease in ambulatory and exploratory activities and an increase in the time spent in inactivity. This was accompanied by a decrease in the activity of TH in the substantia nigra, an effect also previously observed for anandamide.     

Effect of tuftsin on enzyme activity in the energy metabolism of lymphocytes

The cytochemical technique was used to measure the activity of succinate dehydrogenase (SDH), lactate dehydrogenase (LDH) and glucose-6-phosphate dehydrogenase (G-6-PDH) of peripheral blood lymphocytes of mice and rats given intraperitoneal injections of an endogenous immunostimulant tuftcin (Tre-Lys-Pro-Arg) in a dose of 0.3 mg/kg. A significant decrease of SDH activity was observed both in mice and rats 4 and 6 hours following injection, respectively. In mice, that activity returned to normal in 12, while in rats in 24 hours. An opposite action was produced by tuftcin on G-6-PDH, causing the maximum elevation of the enzyme activity in rat lymphocytes 6 hours after peptide administration. The decrease to the initial level was observed in 24 hours. Tuftcin did not affect the activity of LDH. The data obtained indicate that the immunological effect of tuftcin is coupled with the changes in the activity of Krebs cycle enzymes (SDH) and pentose phosphate cycle enzymes (G-6-PDH).     

Dizocilpine-induced neuropathological changes in rat retrosplenial cortex are reversed by subsequent clozapine treatment

In this study, we examined the effect of post-treatment with clozapine on the neuropathological changes in the rat retrosplenial cortex induced by the administration of non-competitive NMDA receptor antagonist dizocilpine ((+)-MK-801). The maximal increase in vacuolized neurons, which are representative of neuropathology, was observed 4 hours after a single injection of dizocilpine (0.5 mg/kg s.c.), with a complete reversal of the neuropathology after 16-24 hours. The administration of clozapine (10 mg/kg, i.p.,) 4 hours after the administration of dizocilpine significantly decreased the number of vacuolized neurons in the retrosplenial cortex 6, 8 or 10 hours after administration of dizocilpine, compared to vehicle-treated animals. Furthermore, the administration of clozapine (5, 10 or 20 mg/kg i.p.) 4 hours after the administration of dizocilpine produced a significant decrease in the number of vacuolized neurons in the retrosplenial cortex in a dose-dependent manner when measure 6 hours post-dizocilpine. These results show that neuropathological changes in the rat retrosplenial cortex produced by dizocilpine can be attenuated by post-treatment with clozapine.     

Differences of behavioral rhythms observed by flat cage and running-wheel cage in female rat

The ambulatory, wheel-running, and drinking activities were measured in Wistar-Imamichi strain female rats under 12 L:12 D condition (6:00-18:00), using Gundai type ambulo-drinkometer (for simultaneous measurements of ambulation and drinking) and wheel-drinkometer (for simultaneous measurements of wheel-running and drinking) to compare the rhythmicities of each behavioral activity. These apparatuses are able to measure the behavioral activities over a long period, successively and automatically. The circadian patterns of ambulatory activity had two large peaks at 21 or 24:00 and at 6:00 (acrophase). Contrary to the above results, the wheel-running activity exhibited clear mono-peak at 21:00 (acrophase). Thus, apparent differences of the pattern were observed between the two activities. However, ambulatory and wheel-running activities fluctuated showing 4-days rhythmicity, and both activities increased in estrus and proestrus stages, respectively. The circadian rhythms of drinking activities measured by both apparatuses showed almost same patterns with acrophases at 6:00, and 4-days rhythmicities were also observed and were characterized by remarkable decrease of activity in every proestrus stages. From these results, it is concluded that circadian pattern of ambulatory activity is different from that of wheel-running activity, but circadian patterns of drinking activities are stable regardless of different methods of the measurement. The ambulatory, wheel-running and drinking activities reflect the behavioral changes in sexual cycles.     

Metabolic adaptation of the renal carbohydrate metabolism. III

Summary The adaptive response of renal metabolism of glucose was studied in isolated rat proximal and distal renal tubules after a high protein-low carbohydrate diet administration. This nutritional situation significantly stimulated the gluconeogenic activity in the renal proximal tubules (about 1.5 fold at 48 hours) due, in part, to a marked increase in the fructose 1,6-bisphosphatase (FBPase) and phosphoenolpyruvate carboxykinase (PEPCK) activities. In this tubular fragment, FBPase activity increased only at subsaturating fructose 1,6-bisphosphate concentration (30% at 48 hours) which involved a significant decrease in the Km (31%) for its substrate without changes in the Vmax. This enzymatic behaviour is probably related to modifications in the activity of the enzyme already present in the renal cells. Proximal PEPCK activity progressively increased at all substrate concentrations (almost 2 fold at 48h of high protein diet) which brought about changes in Vmax without changes in Km. These changes are in agreement with variations in the cellular concentration of the enzyme. Neither gluconeogenesis nor the gluconeogenic enzymes changed in the distal fractions of the renal tubules. On the other hand, a high protein diet did not apparently modify the glycolytic ability in any fragment of the nephron, although a significant increase in the phosphofructokinase (PFK) and pyruvate kinase (PK) activities was found in the distal renal tubules. This short term regulation involved a significant decrease from 24 hours in the Km value of distal PFK (almost 40%) without changes in Vmax. The kinetic behaviour of distal PK was mixed. In the first 24h after high protein diet a significant decrease in the Km for phosphoenolpyruvate was found (30%) without variation in the Vmax, however during the second 24 hours the activity of this glycolytic enzyme increased significantly (almost 1.3 fold) without modifications in its Km value. On the contrary, this nutritional state did not modify the kinetic behaviour of any glycolytic enzyme in the proximal regions of the renal tubules.     

Effects of repeated doses of MDMA ("ecstasy") on cell-mediated immune response in humans.

Cell-mediated immune response after the administration of two repeated doses of 100 mg 3,4-methylenedioxymethamphetamine (MDMA) at 4-hour and 24-hour intervals was evaluated in two randomised, double-blind and cross-over clinical trials conducted in healthy male MDMA consumers. MDMA produced a time-dependent decrease in the CD4/CD8 T-cell ratio due to a decrease in the number of CD4 T-helper cells, a decrease in the functional responsiveness of lymphocytes to mitogenic stimulation, and a simultaneous increase in natural killer cells. In case of two 100 mg MDMA doses given 4 hour apart, immune alterations produced by the first dose were strengthened by the second one. At 24 hours after treatment, statistically significant residual effects were observed for all the altered immune parameters after the administration of two MDMA doses if compared to single dose and placebo. In the second clinical trial, the second 100 mg MDMA dose given 24 hours after the first dose produced immunological changes significantly greater than those induced by the initial drug administration and which seemed to show a delayed onset. Significant residual effects were observed for all the immune parameters as late as 48 hours after the second dose. These results show that repeated administration of MDMA with both a short and a long time interval between doses extends the critical period following MDMA administration, already observed after a single dose, in which immunocompetence is severely compromised.     

Endotoxin and Staphylococcus aureus enterotoxin A induce different patterns of cytokines.

The effects of Staphylococcus aureus enterotoxin A (SEA) and lipopolysaccharide (LPS) in cytokine production were assessed at the single cell level in cells obtained from healthy blood donors. Cytokine production was studied with UV-microscopy of fixed and permeabilized cells stained with cytokine specific monoclonal antibodies. The cytokines evaluated included tumour necrosis factor (TNF)-alpha, interleukin (IL)-1 alpha, IL-1 beta, IL-6, IL-8, IL-10, IL-2, IL-4, interferon (IFN)-gamma and TNF-beta. LPS exhibited marked production of IL-1 alpha, IL-1 beta, TNF-alpha, IL-6 and IL-8. After LPS stimulation IL-1 alpha, IL-1 beta, TNF-alpha and IL-8 were the dominating products, all peaking at or before 4 hours after cell stimulation. In addition, IL-10 production was evident after 12 hours of cell stimulation. The T-lymphocyte-derived cytokines TNF-beta, IL-2, IFN-gamma and IL-4 were never detected in the cultures. All cytokine production, except IL-8, was downregulated at 96 hours. In contrast, peak production of IL-1 alpha, IL-1 beta and IL-8, which were the dominant products, occurred after 12 hours in the SEA-stimulated cultures. Further, a significant T-lymphocyte production of TNF-beta, TNF-alpha, IFN-gamma and IL-2 was found with peak production 12-48 hours after initiation. Only low amounts of IL-6 were evident. The two types of cytokine pattern and kinetics found may correspond to the different clinical conditions after invasive Gram-negative Escherichia coli vs Gram-positive Staphylococcus aureus infections in humans, with a much more rapid onset of disease after E. coli infections.(ABSTRACT TRUNCATED AT 250 WORDS)     

Synergistic effects of cAMP-dependent signalling pathways and IL-1 on IL-6 production by H19-7/IGF-IR neuronal cells

cAMP-dependent signalling cascades regulate a number of CNS functions including brain inflammation processes. In this study, we characterized IL-1-induced IL-6 production in hippocampal cells using H19-7/IGF-IR cells and investigated the effect of changes in intracellular cAMP levels on IL-1 activity. IL-1 potently induced IL-6 mRNA expression with a corresponding increase in IL-6 release, in a time- and dose-dependent manner with a maximal at 24 h and with an EC50 value of 0.11 ng/ml. Cell pre-treatment with the IL-1sR antagonist produced a rightward shift of IL-1 dose-response effect with a corresponding decrease in IL-1 potency. IL-1-induced IL 6 release was attenuated in the presence of the p38 MAPK inhibitor SB203580 but was not significantly affected by the PKA inhibitor KT 5720. Western blotting analysis of phospho-CREB cell content showed a marked increase in CREB activation. Similar results were obtained by pharmacologically increasing cAMP using dibutyryl cyclic adenosine monophosphate (dbcAMP) or the cAMP-specific type-4 phosphodiesterase inhibitor rolipram. Both dbcAMP and rolipram increased IL-6 production to about 50% of IL-1 effect. However, in the presence of IL-1, IL-6 production was further potentiated by either dbcAMP and rolipram, reaching 300% and 500% IL-1-induced levels. These data implicate the role of cAMP-dependent pathways on IL-6 production in neuronal cells and suggest novel synergistic mechanisms of regulation of cytokine production in brain.     

Role of interleukin-6 in growth failure: an animal model

Indirect evidence suggests a link between factors produced during the inflammatory response and stunted growth. The demonstration of this link was provided by the observation that mice transgenic for the inflammatory cytokine interleukin-6 (IL-6), expressing high circulating levels of IL-6 since birth, show a marked decrease in growth rate leading to adult mice 50-70% the size of wild-type littermates. The growth defect is completely abolished by neutralization of IL-6. In these mice the production of GH is normal, while circulating levels of IGF-I are markedly decreased. Administration of IL-6 to wild-type mice results in a marked decrease in IGF-I levels. These observations show that in vivo high levels of IL-6 are associated with low levels of IGF-I. However, IL-6 does not directly affect IGF-I production both in vitro and in vivo. In contrast, markedly decreased levels of IGFBP-3 are present in the IL-6 transgenic mice and administration of IL-6 to wild-type mice results in a marked decrease in IGFBP-3 levels. In these mice the decrease in IGFBP-3 levels is associated with impaired formation of the 150 kD ternary complex, even in the presence of normally functional ALS. As a consequence, IL-6 transgenic mice show increased clearance of circulating IGF-I, suggesting that IL-6 decreases IGF-I levels by increased clearance. Proteolytic degradation of IGFBP-3 occurs in the IL-6 transgenic mice, suggesting that the decrease in IGFBP-3 could be at least in part due to proteolysis. The abnormalities of the IGF-I system observed in the IL-6 transgenic mice are similar to those found in patients with systemic juvenile idiopathic arthritis, one of the chronic inflammatory diseases characterized by stunted growth and prominent production of IL-6. The IL-6 transgenic mice represent a faithful animal model of the growth impairment associated with chronic inflammation and may therefore provide information relevant to the understanding and treatment of this complication of inflammatory diseases.     

Influence of bupropion HCl (Wellbatrin), a novel antidepressant, on plasma levels of prolactin and growth hormone in man and rat.

Bupropion HCl (Wellbatrin®), a non-tricyclic compound with antidepressant effects in man, was evaluated for effects on plasma prolactin (PRL) and growth hormone (GH) levels in normal human subjects, and for effects on plasma PRL levels in a series of pharmacological studies in normal rats. Single oral doses of 50, 100 or 200 mg of bupropion given to male (n=6) and female (n=12) subjects produced a marked suppression (80% decrease) of PRL. Incomplete PRL recovery was observed at the end of 24 hours. One hour after drug administration there was a +0.56 correlation of percent decrease in PRL levels with bupropion plasma levels. GH showed only small and erratic changes in plasma levels at 1–4 hours post-dose. In the rat, single bupropion doses of 25 mg/kg, i.p., failed to lower basal PRL levels. Bupropion, however, significantly decreased PRL in rats in which plasma PRL was elevated by pretreatment with alphamethyltyrosine, 5-hydroxytryptophan or quipazine. Bupropion, on the other hand, did not counteract the PRL-elevating effect of haloperidol. Results in man and rat are consistent with the view that bupropion has significant dopamine mimetic properties. Whether bupropion is a direct dopamine receptor-stimulator or an indirectly acting agonist cannot be determined from the present results.     

LPS／D—GalN诱发ⅣF—KB转基因小鼠急性致死性肝损伤模型的建立

目的以NF—KB转基因BALB／c小鼠建立一个LPS／D—GaIN诱发的急性致死性肝损伤模型。方法采取腹腔注射高剂量的LPS／D-GalN建立急性致死性肝损伤小鼠模型,观察模型小鼠的促炎症细胞因子水平和NF—KB的活性改变,以及肝脏功能和病理改变情况。结果模型组小鼠生存时间为8—10h,模型建立后小鼠血清TNF—a、IL-6和MCP-1水平显著升高,在2—4h达到高峰;肝脏外观出现瘀血和出血,肝脏小叶被严重破坏,肝细胞严重坏死和出血;血清ALT／AST水平在模型诱发后持续迅速上升;整体成像显示胛-KB的活性在4～6h达到高峰。正常对照组小鼠以上指标无显著变化。结论成功建立LPS／D-GalN诱发的M-船转基因小鼠的急性致死性肝损伤模型。     

Soluble cytokine receptors (sIL-2Rα, sIL-2Rβ) induce subunit-specific behavioral responses and accumulate in the cerebral cortex and basal forebrain

Soluble cytokine receptors are normal constituents of body fluids that regulate peripheral cytokine and lymphoid activity. Levels of soluble IL-2 receptors (sIL-2R) are elevated in psychiatric disorders linked with autoimmune processes, including ones in which repetitive stereotypic behaviors and motor disturbances are present. However, there is no evidence that sIL-2Rs (or any peripheral soluble receptor) induce such behavioral changes, or that they localize in relevant brain regions. Here, we determined in male Balb/c mice the effects of single peripheral injections of sIL-2Rα or sIL-2Rβ (0-2 μg/male Balb/c mouse; s.c.) on novelty-induced ambulatory activity and stereotypic motor behaviors. We discovered that sIL-2Rα increased the incidence of in-place stereotypic motor behaviors, including head up head bobbing, rearing/sniffing, turning, and grooming behavior. A wider spectrum of behavioral changes was evident in sIL-2Rβ-treated mice, including increases in vertical and horizontal ambulatory activity and stereotypic motor movements. To our knowledge, this is the first demonstration that soluble receptors induce such behavioral disturbances. In contrast, soluble IL-1 Type-1 receptors (0-4 μg, s.c.) didn't appreciably affect these behaviors. We further demonstrated that sIL-2Rα and sIL-2Rβ induced marked increases in c-Fos in caudate-putamen, nucleus accumbens and prefrontal cortex. Anatomical specificity was supported by the presence of increased activity in lateral caudate in sIL-2Rα treated mice, while sIL-2Rβ treated mice induced greater c-Fos activity in prepyriform cortex. Moreover, injected sIL-2Rs were widely distributed in regions that showed increased c-Fos expression. Thus, sIL-2Rα and sIL-2Rβ induce marked subunit- and soluble cytokine receptor-specific behavioral disturbances, which included increases in the expression of ambulatory activity and stereotypic motor behaviors, while inducing increased neuronal activity localized to cortex and striatum. These findings suggest that sIL-2Rs act as novel immune-to- brain messengers and raise the possibility that they contribute to the disease process in psychiatric disorders in which marked increases in these receptors have been reported.     

Differential regulation of adrenal corticosteroids after restriction-induced drinking in rats

Water-restricted rats exhibit a rapid decrease in plasma corticosterone after drinking. The present study examined the effect of restriction-induced drinking on plasma aldosterone and plasma clearance of corticosterone. Rats were water restricted for 6-7 days and then killed before or 15 min after water administration; plasma and adrenal hormones were assayed. Plasma and adrenal corticosterone decreased after drinking without a change in plasma corticosteroid-binding globulin; plasma ACTH decreased or did not change. In contrast, plasma aldosterone did not change or increased after drinking; plasma renin activity was elevated by water restriction and increased further after drinking. In another experiment, rats were adrenalectomized, and corticosterone and aldosterone were replaced with pellets and osmotic minipumps, respectively. Rats were water restricted and killed. There was a small decrease in plasma corticosterone but no change in aldosterone after drinking in adrenalectomized animals. These data suggest that changes in plasma steroids after restriction-induced drinking result from zone-specific responses of the adrenal to known secretagogues, with minimal contribution from increased plasma clearance.     

EFFECTS OF DOWNHILL AND UPHILL EXERCISES OF EQUIVALENT SUBMAXIMAL INTENSITIES ON SELECTED BLOOD CYTOKINE LEVELS AND BLOOD CREATINE KINASE ACTIVITY

The study was aimed at comparing the effects of concentric (CONC) and eccentric (ECC) exercises of equivalent (in terms of relative work load expressed as a percentage of VO₂max) moderate intensity on selected blood cytokine levels and blood creatine kinase (CK) activity. Twenty recreationally active healthy young male volunteers were randomized between two groups that performed a single 1 h bout of CONC (uphill running) or ECC (downhill running) exercise at 60% of the respective individual VO₂max. Venous blood taken 1 h before, at the end, and 24 h after the exercise was processed for plasma and analyzed for CK activity and IL-6, IL-1β and TNFα levels. There was no between-group difference in these cytokines prior to or just after the exercise, and in pre-exercise CK activity. The cytokines elevated significantly and similarly in both groups during the exercise, with no significant change in CK activity. Twenty-four hours later, CK activity and IL-6 were at pre-exercise levels in the CONC group, but showed further major increases in the ECC group, resulting in marked between-group differences in these indices. Changes in IL-1β and TNFα levels during the recovery period showed only minor differences between the study groups and produced no significant between-group difference in these cytokines. However, IL-1β level normalized in the ECC but not in the CONC group. The study suggests that moderate intensity ECC exercise compared to CONC exercise of equivalent relative work load results in considerably greater muscle damage and its related elevation in circulating IL-6, but it does not cause a major systemic inflammatory response.     

DSIP/DSIP-P and circadian motor activity of rats under continuous light

Daily intravenous injection of 30 nmol/kg DSIP (delta sleep-inducing peptide) in rats under constant illumination produced marked changes of their motor activity as compared to saline controls. Similar marked but distinctly different effects on the circadian pattern of locomotor behavior partially abolished by constant illumination were also obtained after repeated administration of 0.1 nmol/kg DSIP-P (the phosphorylated analogue of DSIP) which enhanced overall motor activity. In both instances the results additionally differed from those reported for a normal 12 hr light:dark cycle. The present results support the hypothesis that DSIP might primarily act by influencing circadian rhythmicity.     

Neurotransmitter-mediated open-field behavioral action of CGRP

The effects of central administration of calcitonin gene-related peptide (CGRP) on open-field activity were examined in male rats. Three doses (250 ng, 500 ng and 1 microg) of CGRP given intracerebroventricularly (i.c.v.) were tested on the ambulatory, rearing and grooming activities of the animals. One microg of peptide significantly decreased the ambulatory activity and increased the rearing and grooming activities 30 min after the treatment. The animals were pretreated with different receptor antagonists in doses which by itself did not affect the behavioural paradigm. The decrease in ambulation induced by CGRP was antagonized by acetylcholine-, opioid-, 5HT-receptor and beta-adrenoceptor antagonists. CGRP induced increase in rearing activity was blocked by naloxone, phenoxybenzamine and propranolol. The CGRP-induced increase in grooming behavior was prevented by atropine, haloperidol, naloxone, methysergide and propranolol. The results suggest that different neurotransmitter systems are involved in the action of CGRP on open-field behavior in rats.