Centrally administered verapamil prevents the autonomic reaction to visceral pain in sheep.

The significant role of voltage gated calcium channels (VGCC) L-type antagonists used concomitantly with opioids in attenuation of clinical pain has been confirmed. The aim of this study was to evaluate the effect of centrally administered verapamil on behavior and biochemical parameters in sheep that have undergone experimental duodenal distension (DD) and to determine whether verapamil exerts any anti-nociceptive effects under these conditions. The study was carried out using 24 mature crossbred ewes, each weighing 38-43 kg. Verapamil, a VGCC blocker, was administered through an intracerebroventricular cannula at the following doses: 0.25, 0.5, 1.0 and 2.0mg in toto. Ten minutes later experimental DD was conducted by insertion and the distension of rubber balloon (containing 40 ml of warm water) inserted into sheep duodenum. After 5 min of mechanical DD the following reactions were then observed: the significant increase in behavioral pain responses, i.e. tachycardia, hyperventilation, inhibition of reticulo-ruminal contractions (70% approximately, during 15 min), an increase of plasma catecholamine concentration (over 7-fold increase of epinephrine during 2h following DD, 2-times norepinephrine and +/-80% increase of dopamine). Verapamil infusion administered 10 min prior to DD decreased intensity of visceral pain responses, such as: behavioral changes, tachycardia, hyperventilation, inhibition of the reticulo-rumen motility and efficiently prevented the appearance of catecholamine release. These data demonstrated that the development and persistence of duodenal hyperalgesia depends on the activation of Ca(2+) ion flux leading to neurotransmitters release and modulation of membrane excitability. The observed antinociceptive action of VGCCs type-L blockers suggests that these channels play a crucial role in the modulation of acute visceral hyperalgesia in sheep.

The inhibition of experimentally induced visceral hyperalgesia by nifedipine - a voltage-gated Ca(2+) channels blocker (VGCCs) in sheep.

Present study examined the effect of VGCC L-type blocker - nifedipine given i.c.v. (0.25, 0.5, 1 and/or 2mg in toto) on the development of nociceptive behavior, clinical symptoms, plasma catecholamin concentration and reticulo-rumen motility following 5 min lasting mechanical duodenal distension (DD) in sheep. After 24h of fasting, all animals received i.m. ketamine analgesia (20 mg kg(-1)B.W) and anesthetized with pentobarbital (20 mg kg(-1)B.W., i.v. infusion) The permanent stainless steel cannula 29 mm in length and 2mm in diameter was inserted into the lateral cerebral ventricle (controlled by cerebro-spinal efflux) 10mm above the bregma and 5mm laterally from the midline sutures using stereotaxic method. Under the same general anesthesia/analgesia a T-shaped silicon cannula (inside diameter of 21 mm), was inserted into the duodenum (12 cm from pylorus). Second identical cannule was inserted into the dorsal sac of the rumen, a previously described. After surgery each animal was kept in individual boxes for 10 days prior to experiment and was treated i.m. with benzyl procaine penicillin 30,000 I.U kg(-1)B.W.)+dihydrostreptomycine sulfate (10 g kg(-1)B.W.)+prednisolone acetate (1.2 mg kg(-1)B.W.) combination and i.m. ketamine (20 mg kg(-1)B.W.) every day by seven consecutive days. Experimental DD was conducted by insertion and then distension of rubber balloon (containing 40 ml of warm water) inserted into sheep duodenum. Duodenal distension produced a significant increase in behavioral pain manifestations, tachycardia, hyperventilation, inhibition of reticulo-ruminal contractions rate (from 87.2 to 38.0% during 15-20 min), an increase of plasma catecholamine concentration (over 6.4-fold increase of epinephrine during 2h following DD, 2-times norepinephrine and 84% increase of dopamine). Nifedipine infusion administered 10 min prior to DD decreased intensity of visceral pain manifestations such as: behavioral changes, hyperventilation, reticulo-rumen motility and efficiently prevent appearance of catecholamine release. These data demonstrated that the development and persistence of duodenal hyperalgesia depends on the activation of Ca(2+) ion flux leading to neurotransmitters release and modulation of membrane excitability. It seems that nifedipine given i.c.v. 10 min prior to DD (as a source of visceral pain), inhibited specific receptors 1 subunits of VGCCs in target tissues, prevented depolarization of cell membranes and release of neurotransmitters responsible for pain sensitivity in sheep. The observed antinociceptive action of VGCCs type L blockers suggest that these channels play a crucial role in the modulation of acute visceral hyperalgesia in sheep.

Centrally administered PD 140.548 N-methyl-D-glucamine prevents the autonomic responses to duodenal pain in sheep.

Cholecystokinin (CCK) released in the CNS inhibits the analgesic action of exogenous opioids and may antagonize analgesia resulting from the activation of an endogenous pain inhibitory system. The aim of this study was to analyse the central action of PD 140.548 N-methyl-D-glucamine--a peptide antagonist of a specific peripheral type CCK receptor--on animal behaviour, catecholamines (CA) and cortisol concentration, as well as clinical symptoms of visceral pain induced by duodenal distension (DD). A 5 min distension of the duodenum wall, using a 10 cm long balloon filled with 40 and/or 80 ml of water (DD 40 and/or DD 80) at animal body temperature, produced a significant increase in plasma CA and cortisol levels, an increase in the heart rate, hyperventilation and other clinical symptoms (inhibition of rumen motility, bleating, teeth grinding, prostration, urination, defecation) that may be related to pain, proportionally to the degree of intestinal distension. Intracerebroventricular administration of PD 140.548 at the dose of 1 or/and 2 mg in toto 10 min before applying DD 40 completely blocked the increase in blood plasma cortisol, epinephrine (E), norepinephrine (NE) and dopamine (DA) concentration. It is suggested that the central inhibitory action of CCK antagonist on the cortisol and catecholamine release produced by visceral pain is due to the inhibition of peripheral CCK1 type receptors in the central centrifugal descending pain facilitatory system in sheep perhaps via the hypothalamic-pituitary-adrenal axis.

Extracellular monoamines and their metabolites in the mediobasal hypothalamus--median eminence of anestrous and estrous ewes during CRF treatment.

In order to clarify the effect of exogenous corticotropin-releasing factor (CRF) on catecholaminergic and serotoninergic system activity in the mediobasal hypothalamus-median eminence (MBH-ME) of ewes the changes in extracellular levels of noradrenaline (NA) and serotonin (5HT), and main metabolites of monoamines, 4-hydroxy-3-methoxyphenylglycol (MHPG), 3,4-dihydroxy-phenylacetic acid (DOPAC), homovanilic acid (HVA), and 5-hydroxy-indolo-3-acetic acid (5-HIAA) were quantified in the perfusates collected from MBH-ME. NA, 5-HT and monoamine metabolites in the perfusates were analyzed using high performance liquid chromatography with electrochemical detection. CRF induced a rise in extracellular concentration of NA and 5-HT only in the estrous ewes prior to a preovulatory LH surge. CRF treatment caused a heterogenous effect on extra-cellular concentrations of 5-HT in ewes during the preovulatory LH surge. Except for DOPAC and HVA in some estrous ewes during the preovulatory LH surge, CRF caused an increase in monoamine metabolites levels in the MBH-ME in anestrous and estrous animals. These results indicate that CRF facilities NA release in the MBH-ME during the presurge LH period in ewes, and that CRF increases metabolic activities of the monoaminergic systems in this structure in the anestrous and estrous ewes, except dopaminergic system in the ewes during the preovulatory LH surge. It is suggested that: 1) the responses of monoaminergic systems activity in the MBH-ME to CRF in large degree is dependent upon physiological state of ewes and 2) in some endocrinological phases CRF may affect LHRH and other hypothalamic hormone secretion indirectly by altering monoaminergic system activity in the MBH-ME.

The immune-neuro-endocrine interactions.

This article reviews data concerning the interactions between immune, endocrine and neural systems in physiological, pathophysiological and stress conditions in animals and humans. Numerous studies have provided evidence that these systems interact with each other in maintaining homeostasis. This interaction may be classified as follows: immune, endocrine and neural cell products coexist in lymphoid, endocrine and neural tissue. Endocrine and neural mediators modulate immune system activity. Immune, endocrine and neural cells express receptors for cytokines, hormones, neuropeptides and transmitters.

Responses in the hypothalamic monoaminergic system activity in ewes to beta-endorphin, CRF and their antagonists.

This article reviews data concerning the action of opioidergic and monoaminergic system on LHRH secretion. Generally, in anestrous ewes beta-endorphin and/or corticoliberin significantly change extracellular concentrations of monoamine metabolites in the MBH-ME, but in estrous ewes both beta-endorphin and CRF alters also dopamine, noradrenaline and serotonin levels. Responses of catecholaminergic and serotoninergic system in the MBH-ME to naloxone or CRF-antagonist depend, to a large degree, on the phase of reproduction. In anestrous ewes subjected to stressful stimuli an opiate receptor blocker, naloxone, and CRF-antagonist attenuate the stress - induced activity of catecholaminergic and serotoninergic system in the MBH-ME; in non-stressed animals they suppress only serotoninergic system activity in this structure. No clear explanation can be offered now for either differences in response of catecholaminergic and serotoninergic system in the MBH to beta-endorphin and CRF in various periods of reproduction or for differences in the responses of these systems to CRF antagonist and naloxone in non-stressed and stressed ewes. It has been suggested that the responses in monoaminergic system activity are highly dependent upon the physiological state of the animal and that beta-endorphin and corticoliberin may indirectly modulate LHRH and other hypothalamic hormone secretion by monoaminergic systems.

[Humoral response to HBV antigens in acute and chronic hepatitis B]. / Odpowiedz humoralna na antygeny HBV w ostrym i przewleklym wir usowym zapaleniu watroby typu B.

Sera of patients with acute and chronic hepatitis B and antigenemia were tested for the presence of anti-HBe and anti-HBs antibodies, free or bound in immune complexes. The possible occurrence of immune complexes of HBcAg in these sera was also investigated. Immune complexes were identified by antigen specific enzyme immunoassay, in which polyclonal antibodies against synthetic fragments of proteins S and C of HBV and mono- and polyclonal anti-HBc antibodies were used as a solid phase. Free and/or antigen bound anti-HBe antibodies were detected in 100% of patients with acute (81% HBeAg positive) and in 37% of patients with chronic hepatitis, all HBeAg positive. Anti-HBs antibodies or their immune complexes were found in 83% and 37% of patients, respectively. In not any patient circulating complexes of HBcAg could be identified. The results obtained support the observations that humoral immune response to HBeAg and HBsAg can be detected earlier than generally accepted; they also suggest that the detection of anti-HBs in a single sample of serum should not be considered as the evidence of elimination of infection.

Catecholaminergic activity in the medial preoptic area and nucleus infundibularis-median eminence of anestrous ewes in normal physiological state and under stress condition.

The stressful events induce in organism both excitatory and inhibitory mechanisms for rapid physiological adjustment to environmental stressors. Pull-push technique was used to determine extracellular concentrations of NE, DA, and their metabolites MHPG and DOPAC in the medial preoptic area (MPOA) and nucleus infundibularis-median eminence (NI/ ME) of anestrous ewes in normal physiological state and under stress condition. In non-stressed ewes the level of NE in the MPOA was substantially lower than in the NI/ME, whereas DA was found only in the NI/ME. No regional differences in the concentrations of MHPG, DOPAC in these structures were found. On the first day, footshock stimulation activated noradrenergic system in the MPOA and both noradrenergic and dopaminergic system in the NI/ME during the first 1.5 h followed by gradual desensitisation of these systems. On the third day during whole period of stimulation the concentration of all these neurochemical compounds were significantly lower than in controls. It indicates that prolonged intermittent stress elicits a neurochemical processes in the MPOA and NI/ME whose effects lead to the suppression of catecholamines release and their metabolism. The basal concentration and stress induced changes of NE, DA, MHPG, DOPAC in the fluid of the III-rd brain ventricle (V-III) reflect a dynamic relationship between extracellular levels of catecholamines and their metabolites in the hypothalamus and cerebral fluid. The consequences of these long-term response of catecholaminergic system in the MPOA and NI/ME may be essential for changes in LHRH release from the hypothalamus which we observed in ewes subjected to prolonged stressful experience (Tomaszewska et al., 1999).

Changes in extracellular LHRH and beta-endorphin-like immunoreactivity in the nucleus infundibularis-median eminence of anestrous ewes under stress condition.

To clarify the effect of beta-endorphin released under stress condition on LHRH secretion, the concentration of LHRH and beta-endorphin-like-immunoreactivity (beta-END-LI) were analysed in perfusates from the nucleus infundibularis-median eminence of anestrous ewes subjected to footshocks stimulation. The dynamics of LHRH and beta-END-LI release during time-course of footshocks stimuli was altered. A brief facilitatory influence of stress on LHRH and beta-END-LI release was observed at the beginning of the stimulation on the first and third day; however the peaks of beta-END-LI were delayed about half an hour in relation to LHRH. Than on the first day of the stimulation LHRH returned to the control value but on the third day it declined below the control levels. Prolonged stress had stimulatory effect on beta-END-LI secretion during first and third day. The presented results indicate that: 1) short stress activates LHRH and beta-END-LI release, 2) prolonged stress has stimulatory effect on beta-END-LI release but leads to suppression of LHRH release. It is suggested that stress-induced beta-endorphin release may be one of the factors responsible for suppression of LHRH activity.