Biphasic alterations in gastrointestinal transit following endotoxaemia in mice

Lipopolysaccharide (LPS)-induced alterations of gastrointestinal transit were studied in mice using activated charcoal. LPS (10 mg kg-1) induced biphasic alterations of intestinal transit. Increase (acceleration phase) and delay (lag phase) in gastrointestinal transit were observed at 90 and 480 min after LPS injection, respectively. LPS administration induced significant increases in tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta and nitrate levels in blood serum with maximal levels observed at 1.5, 4, and 8 h after LPS administration, respectively. The effects of recombinant human lzactoferrin (rhLF) on LPS- induced alteration of gastrointestinal transit, and production of TNF-alpha, IL-1beta and nitrate were also studied. Animals were pretreated with rhLF 24 hours before intraperitoneal administration of LPS. RhLF significantly increased gastrointestinal transit during the lag phase. In addition, rhLF decreased the level of TNF-alpha in endotoxaemic animals. The levels of IL-1beta and nitrate were not significantly changed by rhLF. In conclusion, the effect of LPS on gastrointestinal transit is biphasic and the mechanism controlling the second phase most likely depends on TNF-alpha production, while the first phase most likely does not depend on TNF-alpha. On the other hand, it may be regulated by IL-1beta and nitric oxide production.     

Involvement of cannabinoid‐1 and cannabinoid‐2 receptors in septic ileus

Background Cannabinoid (CB) receptors are involved in the regulation of gastrointestinal (GI) motility under physiological and pathophysiological conditions. We aimed to characterize the possible influence of CB₁ and CB₂ receptors on motility impairment in a model of septic ileus. Methods Lipopolysaccharide (LPS) injections were used to mimic pathophysiological features of septic ileus. Spontaneous jejunal myoelectrical activity was measured in rats in vivo, and upper GI transit was measured in vivo by gavaging of a charcoal marker into the stomach of mice, in absence or presence of LPS, and CB₁ and CB₂ receptor agonists and antagonists. Tumour necrosis factor (TNF)‐α and interleukin (IL)‐6 levels were measured using enzyme‐linked immunosorbent assay. Histology was performed with haematoxylin–eosin staining. Key Results Lipopolysaccharide treatment significantly reduced amplitude and frequency of myoelectric spiking activity and GI transit in vivo in a dose‐dependent manner. TNF‐α and IL‐6 were increased in LPS‐treated animals and histology showed oedema and cell infiltration. Both, the CB₁ agonist HU210 and the CB₂ agonist JWH133 reduced myoelectrical activity whereas the CB₁ antagonist AM251 caused an increase of myoelectrical activity. Pretreatment with AM251 or AM630 prevented against LPS‐induced reduction of myoelectrical activity, and also against the delay of GI transit during septic ileus in vivo. Conclusions & Inferences The LPS model of septic ileus impairs jejunal myoelectrical activity and delays GI transit in vivo. Antagonists at the CB₁ receptor or the CB₂ receptor prevent the delay of GI transit and thus may be powerful tools in the future treatment of septic ileus.     

Elevation of plasma ACTH concentration in rabbits made febrile by systemic injection of bacterial endotoxin

This study was carried out to investigate the adrenocorticotrophic hormone (ACTH) response in rabbits made febrile by systemic injection of lipopolysaccharide (LPS,Salmonella typhosa endotoxin). Intravenous (i.v.) injection of LPS (0.1 μg/kg and 1.0 μg/kg) increased rectal temperature (biphasic fever) and the plasma concentration of ACTH (ACTH response) in a dose-related manner. These responses were suppressed by pretreatment with indomethacin (20 mg/kg, subcutaneously). Intracerebroventricular (i.c.v.) administration of indomethacin (400 μg) had no effect on the ACTH response to LPS, although it significantly suppressed febrile response. Small increases in plasma concentration of ACTH and significant fevers followed i.c.v. administration of prostaglandin E₂ (2 μg) or F_2α (2 μg). I.v. administration of corticotropin releasing factor (CRF) antagonist [α-helical CRF (9–41) (200 μg/kg)] partly suppressed the ACTH increased induced in plasma by i.v. LPS. These results suggest that prostagandins synthesized outside the blood-brain barrier play an important role in the ACTH response and that the mechanism for induction of the ACTH response is not exactly the same as that for the febrile response, although prostaglandins are involved in both responses.     

Lipopolysaccharide-induced production of tumor necrosis factor activity in rats with and without risk factors for stroke

Rats produced more TNF activity in cerebrospinal fluid (CSF) than in blood after intracerebroventricular (i.c.v.) injection of lipopolysaccharide (LPS). After intravenous (i.v.) LPS, blood TNF levels exceeded CSF levels. Thus, brain cells appear to produce TNF in response to LPS. Rats with the stroke-risk factors hypertension or combined hypertension and genetic stroke-proneness produce more TNF in response to a provocative dose of LPS i.v. than control animals free of these risk factors. The possible relevance to stroke vulnerability is discussed.     

Brain interleukin-1beta and tumor necrosis factor-alpha are involved in lipopolysaccharide-induced delayed rectal allodynia in awake rats

Recently, we have developed a model of delayed (12 h) increase in sensitivity (allodynia) to rectal distension (RD) induced by intraperitoneal lipopolysaccharide (LPS) in awake rats. Thus, we examined whether central interleukin-1beta (IL-1beta) and tumor necrosis factor-alpha (TNF-alpha) are involved in LPS response. Abdominal contractions (criterion of visceral pain) were recorded in rats equipped with intramuscular electrodes. RDs were performed at various times after pharmacological treatments. RD induced abdominal contractions from a threshold volume of distension of 0.8 ml. At lowest volume (0.4 ml), this number was significantly increased 12 h after LPS. Intracerebroventricular (i.c.v.) injection of IL-1 receptor antagonist, IL-1beta converting enzyme inhibitor or recombinant human TNF-alpha soluble receptor reduced LPS-induced increase of abdominal contractions at 0.4 ml volume of distension. When injected i.c.v., recombinant human IL-1beta and recombinant bovine TNF-alpha reproduced LPS response at 9 and 12 h and at 6 and 9 h, respectively. These data suggest that IL-1beta and TNF-alpha act centrally to induce delayed rectal hypersensitivity and that central release of these cytokines is responsible of LPS-induced delayed (12 h) rectal allodynia.     

Female Sex Hormones Influence the Febrile Response Induced by Lipopolysaccharide,Cytokines and Prostaglandins but not by Interleukin‐1β in Rats

There are differences in the immune response, and particularly fever, between males and females. In the present study, we investigated how the febrile responses induced by lipopolysaccharide (LPS) and different endogenous pyrogens were affected by female gonadal hormones. The febrile response to i.p. injection of LPS (50 μg/kg) was 40% lower in female rats compared to male or ovariectomised (OVX) female rats. Accordingly, oestrogen replacement in OVX animals reduced LPS‐induced fever. Treatment with the prostaglandin synthesis inhibitor indomethacin (2 mg/kg, i.p. 30 min before) reduced the febrile response induced by LPS in both OVX (88%) and sham‐operated (71%) rats. In line with the enhanced fever in OVX rats, there was increased expression of cyclooxygenase‐2 (COX‐2) in the hypothalamus and elevated levels of prostaglandin E₂ (PGE₂). In addition, OVX rats were hyper‐responsive to PGE₂ injected i.c.v. By contrast to the enhanced fever in response to LPS and PGE₂, the febrile response induced by i.c.v. injection of interleukin (IL)‐1β was unaffected by ovariectomy, whereas the responses induced by tumour necrosis factor (TNF)‐α and macrophage inflammatory protein (MIP)‐1α were completely abrogated. These results suggest that the mediators involved in the febrile response in females are similar to males, although the reduction of female hormones may decrease the responsiveness of some mediators such as TNF‐α and MIP‐1α. Compensatory mechanisms may be activated in females after ovariectomy such as an augmented synthesis of COX‐2 and PGE₂.     

In vivo evidence that activation of tyrosine kinase is a trigger for lipopolysaccharide-induced fever in rats

We measured the rectal temperature of free-moving, conscious rats after intracerebroventricular (i.c.v.) injections of lipopolysaccharide (LPS) and interleukin-1beta (IL-1beta) with or without various antagonists to investigate the mechanisms involved in LPS-induced fever. LPS (3 microg) elicited significant increases in rectal temperature, which lasted from 0.5 h to more than 8 h after administration. This febrile response was inhibited by pretreatment with L-nitro-arginine (LNA), indomethacin (IND), genistein (GEN), tyrphostin 46 and anti-rat IL-1beta antibody (anti-IL-1beta Ab), but was not inhibited by pretreatment with daidzein or chelerythrine (CHE) into the ventricle. LPS (0.3 microg) following orthovanadate (i.c.v.) produced fever, although the small amount of LPS (0.3 microg) or orthovanadate alone showed no effect on rectal temperature. I.c.v. injections of IL-1beta also induced fever of approximately 4-h duration. This effect was inhibited by pretreatment with IND and anti-IL-1beta Ab, but was not inhibited by pretreatment with LNA, GEN or CHE into the ventricle. These findings demonstrate that in the central nervous system, LPS increases IL-1beta production after activation of tyrosine kinase and NO synthase, and IL-1beta promotes prostaglandin production resulting in increased rectal temperature. Activation of tyrosine kinase in the central nervous system is probably a trigger for the febrile response induced by LPS.     

Constitutive expression of p55TNFR mRNA and mitogen-specific up-regulation of TNF alpha and p75TNFR mRNA in mouse brain

Serum tumor necrosis factor (TNF) functions as a mediator of the immune-to-brain axis. Numerous TNF receptor-mediated effects on the nervous system are described but the knowledge about the regional and cellular expression of TNF receptor p55TNFR and p75TNFR in vivo is far from being complete. It is unclear whether TNF mediates its neuroimmune effects alone or in combination with other factors, e.g., bacterial mitogens. Here, we investigated the distribution of TNFalpha, p55TNFR, and p75TNFR in normal mouse brain and examined the stimulus-specific effects of lipopolysaccharide (LPS) and staphylococcal enterotoxin B (SEB) on the expression of the cerebral TNF system. Both mitogens caused enhanced TNFalpha serum levels and induced c-fos mRNA in the paraventricular nucleus but exhibited different effects on the cerebral gene expression of the TNF system. LPS but not SEB rapidly induced TNFalpha mRNA in circumventricular organs (CVOs) followed by spreading of TNFalpha mRNA into brain parenchyma close to the CVOs. The p55TNFR gene was constitutively expressed in many neurons with high levels in brainstem motor nuclei and in neurons of the sensory mesencephalic trigeminal nucleus. Moderate levels of p75TNFR mRNA were seen in single cells scattered throughout the brain in a pattern resembling microglia. Neither LPS nor SEB modulated the p55TNFR gene expression in any region or cell type of the brain, and LPS but not SEB induced p75TNFR mRNA in the CVOs. Thus, enhanced TNF serum levels able to stimulate c-fos mRNA expression in the paraventricular nucleus did not necessarily result in a modulation of the cerebral TNF system.     

Metastatic-promoting effects of LPS: sexual dimorphism and mediation by catecholamines and prostaglandins

Inflammation is implicated in several medical conditions that are sexually dimorphic, including depression, cardiovascular diseases, autoimmunity, and presumably cancer progression. Here we studied the effects of the proinflammatory agent, LPS, on MADB106 lung tumor retention (LTR), and sought to elucidate underlying mechanisms and sexual dimorphism. F344 male and female rats were administered with LPS (0.001-1mg/kg i.v.) simultaneously with tumor cell inoculation, and treated with a beta-blocker (nadolol, 0.2-0.3mg/kg s.c.), a COX inhibitor (indomethacin, 4mg/kg s.c.) or both drugs. To study the role of NK cells, numbers and cytotoxicity of marginating-pulmonary NK cells were studied, and selective in vivo NK-depletion was employed. Serum levels of corticosterone, IL-6, and TNF-alpha were also assessed. The findings indicated that LPS increased LTR in both sexes, but 10-fold higher doses were needed in females to reach the increase evident in males. Additionally, nadolol and indomethacin reduced the effects of LPS, more so in males. In vivo NK-depletion and ex vivo NK activity studies suggested that LPS affected LTR through both NK-independent and NK-dependent mechanisms, the latter mediated through prostaglandin release in males. Corticosterone, IL-6, and TNF-alpha responses to LPS were sexually dimorphic, but were not associated with LPS or drugs' impacts on LTR. Overall, our findings demonstrate sexual dimorphism in LPS-induced elevated susceptibility to MADB106 experimental metastasis, and in potential humoral underlying mechanisms. Further studies are needed to elucidate additional immunological and non-immunological mediators of these dimorphisms, as well as to assess their involvement in other sexually dimorphic pathologies that are associated with inflammation.     

Different receptor mechanisms mediate the effects of endotoxin and interleukin-1 on female sexual behavior

Activation of the immune system by lipopolysaccharide (LPS) produces physiological, neuroendocrine and behavioral effects, some of which are mediated by cytokine production. We have previously shown that the cytokine interleukin-1 (IL-1) inhibits sexual behavior in female, but not male rats, while producing a comparable suppression of locomotion in both sexes. The present study examined the effects of LPS on sexual behavior and locomotion of male and female rats, and the involvement of IL-1 receptors in mediating the effects of IL-1 and LPS on females' behavior. Peripheral (i.p.) administration of LPS (50 or 250 μg/kg) significantly decreased sexual behavior in females, up to 6 h after administration, while it had no effect on male sexual behavior. However, locomotor activity, measured in the open-field test, was similarly reduced by LPS in both males and females. Pretreatment with the IL-1 receptor antagonist (IL-1ra) either i.p. (10 mg/kg) or intracerebroventricularly (i.c.v.) (50 μg/rat) did not prevent the inhibition of female sexual behavior and locomotion induced by either i.p. (50 μg/kg) or i.c.v. (200 or 400 ng/rat) administration of LPS, respectively. However, identical doses of IL-1ra significantly reversed the effects of IL-1β, administered either i.p. (5 μg/kg) or i.c.v. (50 ng/rat), respectively. These results demonstrate that both LPS and IL-1β produce marked inhibition of sexual behavior in female, but not in male rats. However, IL-1 receptors are not required for the effects of LPS on sexual behavior in female rats.     

Role of prostaglandin,endothelin and sympathetic nervous system on the L-NAME-induced pressor responses in spontaneously hypertensive rats

We tested the hypothesis that in spontaneously hypertensive rat (SHR) NO produced centrally influences the resting arterial blood pressure by attenuating mechanisms involving prostaglandins, angiotensin II, endothelin and sympathetic nervous system. L-NAME (200 micro g/5 micro l), an inhibitor of NO synthase, administered intracerebroventricularly (i.c.v.) to awake and freely moving rats increased mean arterial blood pressure (MABP) in a biphasic pattern: an early transient increase within 1 min and a late prolonged response starting at 45 min and persisting for the duration of experiment (180 min). The two pressor responses involve different neurochemical mechanisms and, based on their latencies, they appear to reflect different anatomical sites of action of L-NAME. The late, but not the early pressor response, was prevented by pretreatment with chlorisondamine (2.5 mg/kg, i.v.), a ganglionic blocker, indicating its dependence on the sympathetic nervous system. Both pressor responses were abolished by i.c.v. pretreatment with indomethacin (200 micro g/5 micro l, i.c.v.), an inhibitor of cyclo-oxygenase, showing that they are mediated by prostaglandin(s). In contrast, losartan (25 micro g/5 micro l), an angiotensin II AT(1) receptor antagonist, had no effect. The initial pressor response was also attenuated by pretreatment with the endothelin ET(A)/ET(B) receptor antagonist, PD 145065 (48 micro g/2 micro l, i.c.v.). Intravenous pretreatment with another ET(A)/ET(B) receptor antagonist, L-754,142 (15 mg/kg as a bolus+15 mg/kg/h for 180 min), however, attenuated both responses to L-NAME. It is possible that L-754,142 crossed the blood-brain barrier and blocked, in addition, central ET(A)/ET(B) receptors. These studies show that NO synthesized in the brain attenuates pressor mechanisms involving prostaglandin, endothelin and sympathetic nervous system, but not angiotensin II, to modulate resting arterial blood pressure.     

Intracerebroventricularly administered lipopolysaccharide enhances spike-wave discharges in freely moving WAG/Rij rats

Peripheral lipopolysaccharide (LPS) injection enhances spike-wave discharges (SWDs) in the genetic rat model of absence epilepsy (Wistar Albino Glaxo/Rijswijk rats: WAG/Rij rats) parallel with the peripheral proinflammatory cytokine responses. The effect of centrally administered LPS on the absence-like epileptic activity is not known, however despite the important differences in inflammatory mechanisms. To examine the effect of centrally administered LPS on the pathological synchronization we intracerebroventricularly (i.c.v.) injected LPS into WAG/Rij rats and measured the number and duration of SWDs. I.c.v. injected LPS increased the number and duration of SWDs for 3 h, thereafter, a decrease in epileptic activity was observed. To further investigate the nature of this effect, a non-steroid anti-inflammatory drug (indomethacin; IND) or a competitive N-methyl-d-aspartate (NMDA) receptor antagonist (2-amino-5-phosphonopentanoic acid; AP5) was injected intraperitoneally (i.p.), preceding the i.c.v. LPS treatment. IND abolished the i.c.v. LPS induced changes in SWDs, while AP5 extended it for 5 h. As control treatments, both IND and AP5 application by themselves decreased the number of SWDs for 2 and 3 h, respectively. Our results show that centrally injected LPS, likewise the peripheral injection, can increase the number and duration of SWDs in the WAG/Rij rat, and the effect invoke inflammatory cytokines as well as excitatory neurotransmitters.     

Central nervous action of interleukin-1 mediates activation of limbic structures and behavioural depression in response to peripheral administration of bacterial lipopolysaccharide

Although receptors for the pro-inflammatory cytokine interleukin-1 have long been known to be expressed in the brain, their role in fever and behavioural depression observed during the acute phase response (APR) to tissue infection remains unclear. This may in part be due to the fact that interleukin-1 in the brain is bioactive only several hours after peripheral administration of bacterial lipopolysaccharide (LPS). To study the role of cerebral interleukin-1 action in temperature and behavioural changes, and activation of brain structures during the APR, interleukin-1 receptor antagonist (IL-1ra; 100 μg) was infused into the lateral brain ventricle 4 h after intraperitoneal (i.p.) LPS injection (250 μg/kg) in rats. I.p. LPS administration induced interleukin-1β (IL-1β) production in systemic circulation as well as in brain circumventricular organs and the choroid plexus. Intracerebroventricular (i.c.v.) infusion of IL-1ra 4 h after i.p. LPS injection attenuated the reduction in social interaction, a cardinal sign of behavioural depression during sickness, and c-Fos expression in the amygdala and bed nucleus of the stria terminalis. However, LPS-induced fever, rises in plasma corticosterone, body weight loss and c-Fos expression in the hypothalamus and caudal brainstem were not altered by i.c.v. infusion of IL-1ra. These findings, together with our previous observations showing that i.c.v. infused IL-1ra diffuses throughout perivascular spaces, where macrophages express interleukin-1 receptors, can be interpreted to suggest that circulating or locally produced brain IL-1β acts on these cells to bring about behavioural depression and activation of limbic structures during the APR after peripheral LPS administration.     

Lipopolysaccharide- and tumor necrosis factor-alpha-induced changes in prolactin secretion and dopaminergic activity in the hypothalamic-pituitary axis

Bacterial lipopolysaccharide (LPS) affects pituitary hormone secretion, including prolactin release, by inducing synthesis and release of cytokines such as tumor necrosis factor-alpha (TNF-alpha). Since prolactin is mainly under tonic inhibitory control of dopamine, we investigated the effect of LPS and TNF-alpha on the hypothalamic-pituitary dopaminergic system. LPS (100-250 microg/rat, i.p.) decreased serum prolactin levels after 1 or 3 h. Sulpiride, a dopaminergic antagonist, increased serum prolactin and blocked the inhibitory effect of LPS. LPS increased hypothalamic dopamine and DOPAC concentrations and the DOPAC/dopamine ratio both in mediobasal hypothalamus and the posterior pituitary. LPS also enhanced dopamine and DOPAC concentration in the anterior pituitary. LPS elevated plasma levels of epinephrine, norepinephrine and dopamine but it did not modify the concentration of epinephrine or norepinephrine in the tissues studied. The administration of TNF-alpha (i.c.v., 1 h, 100 ng/rat) decreased serum prolactin but did not affect plasma catecholamine levels. TNF-alpha did not modify the DOPAC/dopamine ratio in hypothalamus or posterior pituitary but increased dopamine and DOPAC concentrations in the anterior pituitary. Incubations of hypothalamic explants showed that TNF-alpha did not modify in vitro basal dopamine release and reduced K(+)-evoked dopamine release. On the contrary, incubations of posterior pituitaries showed that TNF-alpha significantly increased basal and K(+)-evoked dopamine release. These results indicate that LPS and TNF-alpha increase dopamine turnover in the hypothalamic-pituitary axis. This increase in dopaminergic activity could mediate the inhibitory effect of LPS and TNF-alpha on prolactin release. Furthermore, the increase in dopaminergic activity elicited by LPS could be mediated by an increase in hypothalamic TNF-alpha during endotoxemia.     

INVOLVEMENT OF NMDA RECEPTORS IN MORPHINE STATE–DEPENDENT LEARNING IN MICE

In the present study, the effects of intracerebroventricular (i.c.v.) injection of NMDA receptor agonist and antagonist on impairment of memory formation and the state-dependent learning by morphine have been investigated in mice. Pretraining administration of morphine (5 mg/kg; s.c.) decreased the learning of one-trial passive avoidance task. Pretest administration of morphine (5 mg/kg) induced state-dependent learning acquired under pretraining morphine influence. Pretest administration of NMDA receptor agonist, L-glutamate (0.00001 and 0.0001 and 0.001 μg/mouse, i.c.v.) following pretraining saline treatment did not affect retention. Amnesia induced by pretraining morphine was significantly reversed by pretest administration of L-glutamate (0.0001 and 0.001 μg/mouse, i.c.v.). Pretest administration of noncompetitive NMDA receptor antagonist, MK-801 (0.5, 1, and 2 μg/mouse, i.c.v.) significantly impaired memory formation. Amnesia induced by pretraining morphine was increased by pretest administration of MK-801 (2 μg/mouse, i.c.v.). Pretest coadministration of L-glutamate (0.0001 and 0.001 μg/mouse, i.c.v.) or MK-801 (0.5, 1, and 2 μg/mouse, i.c.v.) with morphine (5 mg/kg, s.c.) increased and decreased morphine state-dependent learning, respectively. The results suggest that NMDA receptors are involved in morphine state–dependent learning in mice.     

Possible mechanism of hypothermia induced by intracerebroventricular injection of orphanin FQ/nociceptin

Orphanin/nociceptin (OFQ/N), a 17-amino-acid peptide, is an endogenous peptide, the receptor for which is similar to mu-, delta- and kappa-opioid receptors ( approximately 65% homology). Reports indicate that OFQ/N can block the antinociception induced by mu-, delta- and kappa-opioid agonists in the rat and in the mouse, indicating that there is a functional interaction between opioid receptors and OFQ/N receptors in the nervous system. It is well known that activation of the mu- and kappa-opioid receptors results in hyperthermia and hypothermia, respectively, in Sprague-Dawley rats. The present studies were designed to examine effects of OFQ/N on body temperature (Tb) and explore whether the mechanism of T(b) change induced by OFQ/N involved the opioid system. The results show that (1) i.c.v. injection of a high dose of OFQ/N (9-18 micro g) produces hypothermia in adult rats; (2) OFQ/N (1.8 micro g, i.c.v., t=+30 s after morphine) can decrease morphine-induced hyperthermia; (3) neither the opioid receptor antagonist, naloxone (10 mg/kg, s.c., t=-15 s before OFQ/N) nor the kappa-opioid receptor antagonist nor-BNI (1 micro g/5 microl, i.c.v., t=-30 s before OFQ/N) reduces the hypothermia induced by i.c.v. injection of OFQ/N at dose of 18 micro g (P>0.05); (4) 60 micro g/5 microl AS oligo (i.c.v. treatment on days 1, 3 and 5) against OFQ/N receptors significantly reduces the hypothermia induced by i.c.v. injection of 9 micro g OFQ/N (P<0.01). These results suggest that the hypothermia induced by i.c.v. injection of a high dose of OFQ/N (9 or 18 micro g) is mediated, at least partially, by its own receptor, independent or downstream of opioid receptors in the rat brain and that OFQ/N probably acts as a physiological antagonist to reduce morphine-induced hyperthermia.     

Age-related changes to tumor necrosis factor receptors affect neuron survival in the presence of beta-amyloid

Inflammation including local accumulations of tumor necrosis factor alpha (TNF-alpha) is a part of Alzheimer's disease pathology and may exacerbate age-related neurodegeneration. Most studies on TNF-alpha and TNF neuronal receptors are conducted by using embryonic neurons. Few studies consider age-related deficits that may occur in neurons. Age-related changes in susceptibility to TNF-alpha through TNF receptor 1 (TNFR1) and receptor 2 (TNFR2) expression could increase susceptibility to beta-amyloid (1-42, Abeta42). Evidence is conflicting about which receptor mediates survival and/or apoptosis. We determined how aging affects receptor expression in cultured adult rat cortical neurons. Old neurons were more susceptible to Abeta42 toxicity than middle-aged neurons, and the addition of TNF-alpha was neuroprotective in middle-aged neurons, but exacerbated the toxicity from Abeta42 in old neurons. These pathologic and protective responses in old and middle-aged neurons, respectively, correlated with higher starting TNFR1 and TNFR2 mRNA levels in old vs. middle-aged neurons. Middle-aged neurons treated with TNF-alpha plus Abeta42 did not show an increase in either TNFR1 or TNFR2 mRNA, but old neurons showed an up-regulation in TNFR2 mRNA and not TNFR1 mRNA. Despite these mRNA changes, surface immunoreactivity of both TNFR1 and TNFR2 increased with the dose of TNF-alpha in middle-aged neurons. However, middle-aged neurons treated with TNF-alpha plus Abeta42 showed an up-regulation in both TNFR1 and TNFR2 surface expression, whereas old neurons failed to up-regulate surface expression of either receptor. These findings support the hypothesis that age-related changes in TNF-alpha surface receptor expression contribute to the neuronal loss associated with inflammation in Alzheimer's disease.     

Recovery of gastrointestinal motility from post-operative ileus in dogs: effects of Leu13-motilin (KW-5139) and prostaglandin F2α

Abstract Cyclical motor activity of the gastrointestinal tract, normally occurring during the interdigestive period in several mammals, is disrupted in the post-operative ileus. We determined the recovery from the disappearance of cyclical motor activity, from the stomach to the colon, in dogs after laparotomy with the force transducers. Moreover, we examined the effects of Leu¹³-motilin (KW-5139) and prostaglandin F2a (PGF2a), administered in the early post-operative period, on the gastrointestinal motility. Following laparotomy, the cyclical motor activity reappeared firstly in the ileum and the colon, then in the jejunum and the duodenum, and finally in the stomach. The reappearance time of the phase III contractions in the stomach was 105.8 ± 10.6 h (n = 4). In the early postoperative period, KW-5139 (0.5 μg kg^?1, i.v.) induced phase-III-like contractions, whereas PGF2a (50 μg kg^?1, i.v.) induced simultaneously occurring contractions over the whole gastrointestine. The treatment with KW-5139 (0.5 μg kg^?1, i.v.) four times (twice daily on the first and the second post-operative day) significantly (P < 0.05) shortened the time required to recover the phase III contractions in the stomach (64.2 ± 2.2 h, n = 4), whereas that with PGF2a (50 μg kg^?1, i.v.) four times did not (111.3 ± 17.2 h, n = 4). The present results indicate that, after laparotomy, the cyclical motor activity recovers faster in the distal intestine than in the proximal intestine and the stomach, and that KW-5139, but not PGF2a, shortens the reappearance time of the phase III activity in the stomach.