Pharmacological modulation of beta-endorphin in rat peritoneal macrophages

The neuropeptide beta-endorphin is present in cells of the immune system, i.e., lymphocytes and monocytes, and its expression can be induced by immunological stimuli. In the present study, we showed that the increase of the serotoninergic availability induces an increase of beta-endorphin concentrations in rat peritoneal macrophages that is blunted by the administration of serotonin receptor antagonists. A significant increase of beta-endorphin concentrations is also evident after blocking the dopaminergic receptors, whereas a dopaminergic agonist decreases the concentrations of the peptide. Our data are consistent with a similar modulation of beta-endorphin concentrations in central nervous system and in immune cells, e.g., rat peritoneal macrophages.

Central nervous system neuropeptides after peripheral nerve deafferentation

Beta-endorphin, Met-enkephalin, substance P, somatostatin and dynorphin concentrations were evaluated in right and left brain areas, and in cervical, thoracic, and lumbosacral spinal cord of rats that underwent section of either the right, the left, both sciatic nerves, the right brachial plexus, the saphenous, or the sural nerve. With all the surgeries, beta-endorphin concentrations decreased significantly in all brain areas with the exception of the striatum where they did not change. By contrast Met-enkephalin increased in all brain areas and in the spinal cord tracts interested by the lesions. The other peptides were always unaffected. The changes in the concentrations of the neuropeptides were observed starting twenty-four hours after surgery and lasted for at least four months. We did not find a lateralization in the brain peptide concentrations of either sham operated or unilaterally deafferentated rats. Moreover, the treatment with serotoninergic agents normalized the concentrations of beta-endorphin, suggesting a role of the serotoninergic system in the decrease of the peptide that follows the lesion of peripheral nerves.

Chronic intrathecal cannulation affects hypothalamic beta-endorphin and met-enkephalin concentrations

Beta-endorphin concentrations decrease and met-enkephalin concentrations increase in the hypothalamus of rats bearing a chronic intrathecal cannula. The modification of the concentrations of beta-endorphin is already present on day 1 after surgery, whereas met-enkephalin is affected starting on day 6, and both peptides are still modified on day 10. These results indicate that chronically cannulated rats are not to be considered normal animals.

Effect of chronic morphine on plasma and brain beta endorphin and methionine enkephalin in pregnant rats and in their fetuses or newborn

Normal or pregnant rats were treated orally for 21 days or throughout pregnancy with water or increasing doses of morphine and killed on days 7, 14, and 21 of pregnancy and 1 day post partum. At these time intervals, plasma, pituitary, and hypothalamic concentrations of beta-endorphin and methionine enkephalin were measured in normal and pregnant rats. Moreover, pituitary and hypothalamic concentrations of the two peptides were also measured in fetuses and newborn. Plasma beta-endorphin and methionine enkephalin increased significantly during pregnancy without any specific effect of morphine. Pituitary concentrations of beta-endorphin were not modified either by pregnancy or morphine treatment, while methionine enkephalin concentrations increased on days 7 and 11 of pregnancy, in both water- and morphine-treated rats. The pattern of the two peptides in the hypothalamus is completely superimposable to the one present in the pituitary with the exception of an increase of beta-endorphin on day 21 of pregnancy, which is more evident in control animals. Consistently with our observations in human newborn and the neurological dysfunctions we observed in them, the concentrations of both the peptides are significantly increased in the hypothalamus of fetuses and newborn of morphine-treated mothers, while in the pituitary only beta-endorphin concentrations are increased.

Cholecystokinin and the immune system: receptor-mediated chemotaxis of human and rat monocytes

The ability of the peptide cholecystokinin (CCK) to induce monocyte chemotaxis was tested both in vivo and in vitro. In the in vitro assay, the activity of different forms of CCK on human monocytes was studied demonstrating the importance of sulfation on tyrosine for the chemotactic activity. CCK receptor antagonists benzotript and CR-1369 are able to block CCK 8 sulfated chemotaxis, thus suggesting the presence of CCK receptors on human monocytes. In both acute and chronic experiments, the peptide specifically increases the number of peritoneal macrophages, when injected into rat peritoneal cavity. These data suggest that immune system cell migration from one body compartment to another can be produced by a neuropeptide receptor-mediated process.

Autotomy and central nervous system neuropeptides after section of the sciatic nerve in rats of different strains

Autotomy and the concentrations of beta-endorphin and Met-enkephalin in brain areas and the spinal cord were measured in Sprague Dawley, Wistar and Wistar Lewis rats thirty-five days after the section of one sciatic nerve. As expected, autotomy developed in Sprague Dawley and Wistar, but not in Wistar Lewis rats. In the Wistar Lewis, brain and spinal cord concentrations of Met-enkephalin increased, beta-endorphin concentrations were unchanged. In Wistar and Sprague Dawley rats the increase of Met-enkephalin was accompanied by a decrease of beta-endorphin. Administration of chlomipramine, a drug usually employed in the treatment of deafferentiation pain, normalized the concentrations of beta-endorphin in the Sprague Dawley and Wistar rats, and avoided the development of autotomy, while Met-enkephalin concentrations did never change. The data presented suggest a possible correlation between beta-endorphin and autotomy.

Brain and spinal cord neuropeptides in adjuvant induced arthritis in rats

The concentrations of brain and spinal cord beta-endorphin, met-enkephalin, dynorphin and substance P were measured in rats bearing the Freund adjuvant induced arthritis. Beta-endorphin brain concentrations decreased gradually in time with a nadir on day twenty-one, when arthritis was at its maximum, and were back to normal by day thirty-five, when arthritis was no more evident. Met-enkephalin concentrations increased in brain areas and in the lumbar spinal cord and returned to normal with the same time pattern, while dynorphin and substance P concentrations did not change. These data indicate that peripheral lesions can induce important changes in brain concentrations of some opioid peptides involved in the modulation of pain.

Endogenous opioids and their receptors in stress-induced analgesia

Stress can induce a naloxone reversible and a naloxone non reversible analgesia according to its parameters. We showed that naloxone non reversible analgesia can be reversed by antagonists of the kappa opiate receptor and that naloxone reversible analgesia can be related to mu receptors and beta-endorphin, while the kappa receptor mediated analgesia can be related to dynorphin. We have also shown that the characteristics of the receptors might change in consequence to stress and that the analgesic responses might be modulated by benzodiazepine agonists and antagonists.

Dissociation of tolerance and dependence to morphine: a possible role for cholecystokinin

Since cholecystokinin (CCK) has been suggested to be an endogenous opiate antagonist, we tried to evaluate if this peptide could be involved in the development of tolerance to morphine. Naive rats were chronically administered morphine, either alone or concomitantly with proglumide or benzotript, two putative CCK receptor antagonists. Chronic treatments with both CCK antagonists alone were also established. Drugs were administered by the oral route, dissolved in the drinking water. At the end of the chronic treatments, the development of tolerance to morphine was assessed by an evaluation of the analgesic responses evoked by graded doses of acutely injected morphine in the tail-flick and hot plate tests. Proglumide and benzotript were able to inhibit the shift to the right of the dose-response curve for morphine, i.e. they prevented the development of tolerance to morphine-induced analgesia. Chronically given alone, the two CCK antagonists never modified the responses to the acute challenge with morphine. We also determined the development of physical dependence by looking at the withdrawal syndrome precipitated by graded doses of acutely injected naloxone. In these experiments the concomitant treatment with morphine and proglumide or benzotript did not modify the occurrence of dependence. These observations are consistent with the hypothesis of CCK being an endogenous opiate antagonist, involved in the development of tolerance to morphine-induced analgesia but not of dependence. Moreover, tolerance to and dependence on morphine can be pharmacologically dissociated.

Analgesic effect of morphine: a role for beta-endorphin

Capsaicin, a neurotoxic agent that induces a decrease in hypothalamic beta-endorphin, a specific antiserum and human beta-endorphin fragment 6 31, a peptidergic beta-endorphin antagonist have been used in the attempt of selectively affecting the function of beta-endorphinergic system and of evaluating the possible role of this peptide in the analgesic effect of morphine. All 3 experimental approaches resulted in a decrease of the analgesia induced by morphine, thus suggesting that beta-endorphin is involved in the effect of morphine.

Vasoactive intestinal peptide 1-12: a ligand for the CD4 (T4)/human immunodeficiency virus receptor

A five-amino-acid (TDNYT) sequence of vasoactive intestinal polypeptide (VIP) shares homology with the proposed attachment sequences of the human immunodeficiency virus (HIV). Synthetic peptides with these sequences have previously been shown to block viral envelope (gp120) binding and HIV infectivity and to serve as agonists of the CD4 (or T4) receptor. Utilizing an in vitro human monocyte chemotaxis bioassay we examined novel synthetic VIP and gp120 sequences and characterized their pharmacological activities on monocyte chemotaxis. CD4 receptor activity is primarily specified by N-terminal (VIP [1-12]) amino acids. The profound immunosuppression of AIDS is not easily explained solely by virus infection. Recently described immunological functions of VIP are similar to some of the immunological abnormalities shown by patients with AIDS. An overproduction of a VIP-like molecule from viral sources (e.g. gp120) could explain some of the immune system impairments which have been described in AIDS.

A role for serotonin and beta-endorphin in the analgesia induced by some tricyclic antidepressant drugs

The analgesic effect of acute or chronic nortriptyline, amitriptyline and their effects on morphine induced analgesia were evaluated in the rat. Clomipramine and amitriptyline, but not Nortriptyline, induce analgesia, while all potentiate the effect of morphine when administered acutely. The analgesic effect of clomipramine is blunted by both the serotonin antagonist metergoline and the opiate receptor blocker naloxone, thus indicating an involvement of both the serotoninergic and endogenous opioid system. The involvement of the serotoninergic system is confirmed by the similar results obtained with the serotonin precursor 5-hydroxytryptophan administered alone or together with morphine. A relation between the serotoninergic and the endogenous opioid systems is also shown by the increase in hypothalamic beta-endorphin concentrations elicited by all the drugs used after acute or chronic treatment, with the only exception of nortriptyline, that has been shown to exert its effects mainly through the noradrenergic system. In conclusion, the analgesic effect of clomipramine and amitriptyline and their potentiation of morphine induced analgesia seems to be related to an activation of the endogenous opioid system mediated by serotonin.

Analgesic effects of mu antagonists after naloxone non-reversible stress-induced analgesia

Three antagonists at the mu opiate receptor site: naloxone, naltrexone and diprenorphine, and one agonist-antagonist compound nalorphine, at doses usually not analgesic elicited analgesia in rats when administered after non-naloxone-reversible shock-induced analgesia had disappeared. The chi receptor antagonist, MR 2266, and the delta antagonist, ICI 154129, were all ineffective. This effect was no longer present when non-naloxone-reversible shock-induced analgesia was inhibited by the administration of the chi receptor antagonist, MR 2266. These results suggest that the mu opiate receptor may change its conformation under particular conditions such as continuous inescapable shock.

Naloxone-reversible and non-reversible shock-induced analgesia during development

We evaluated the development of naloxone-reversible and naloxone-non-reversible analgesia induced by footshock in rats of different ages and correlated it with the concentrations of beta-endorphin and dynorphin in brain areas and the spinal cord. We observed that naloxone-non-reversible shock-induced analgesia appeared first and its appearance might be related to the early presence of high dynorphin concentrations in the spinal cord. Naloxone-reversible analgesia appeared later together with the reaching of adult concentrations of cerebral beta-endorphin.

Baclofen prolongs the analgesic effect of fentanyl in man

Pretreatment with baclofen prolonged the duration of fentanyl-induced analgesia from 18 to 30 min in patients undergoing neurosurgical anaesthesia (fentanyl plus nitrous oxide in oxygen). This observation is consistent with a potentiating effect of GABA on opioid analgesia.

Mainly mu-opiate receptors are involved in luteinizing hormone and prolactin secretion

We evaluated plasma PRL and LH concentrations in the rat after the administration of drugs that exert a specificity directed mainly, although not absolutely, toward the mu-, delta-, or kappa-opiate receptors, in order to investigate the role of different receptors and thus the respective endogenous ligands in the modulation of the release of these anterior pituitary hormones. LH concentrations were evaluated in prepuberal female rats, in adult male rats, and in ovariectomized, estradiol benzoate-treated rats. PRL concentrations were evaluated in suckling rats, in ovariectomized, estradiol benzoate-treated rats, and in ether-stressed rats. The delta-antagonist ICI 154129 never affected PRL or LH concentrations, whereas both the mu- and kappa-antagonists, naloxone and MR 1452, respectively, seemed to be effective. However, when graded doses of the two classes of antagonists were tested, the mu-antagonist appeared to be effective on both hormones at doses that were one tenth of those of the kappa-antagonist. In conclusion, the mu-receptor seems to be the most profoundly involved in the regulation of PRL and LH secretion.

Diclofenac and pirprofen modify pituitary and hypothalamic beta-endorphin concentrations

We provide evidence that both Diclofenac and Pirprofen, two cyclooxygenase inhibitors with a potent analgesic effect both in the experimental animal and in man, induce a significant and long lasting decrease in pituitary beta-endorphin concentrations, together with an increase of the hypothalamic concentrations of the peptide. We suggest that this effect might participate in the potent analgesic effect of the two compounds, that exceeds the one expected by drugs of this class.

Antiepileptic agents affect hypothalamic beta-endorphin concentrations

beta-Endorphin, Met-enkephalin, substance P, and somatostatin concentrations were evaluated in the hypothalami of rats treated either acutely or chronically (15 days) with sodium valproate, diphenylhydantoin, phenobarbital, or ethosuximide. All of these drugs, with the exception of ethosuximide, induced significant decreases in beta-endorphin concentrations after acute treatment, while only sodium valproate induced a decrease after chronic treatment. The acute and chronic effects of sodium valproate were also produced by aminooxyacetic acid, an inhibitor of gamma-aminobutyric acid (GABA) transaminase, while another GABA transaminase inhibitor, ethanolamine-O-sulphate, and THIP, a GABA receptor agonist, were effective after acute administration. Metenkephalin, substance P, and somatostatin concentrations were never affected by the drugs used. The present results, indicating that antiepileptic agents specifically decrease beta-endorphin concentrations, seem to correlate well with the capacity of these agents to blunt the epileptic activity of the peptides tested. Moreover, our data suggest that GABA may be involved in the anticonvulsant-induced reduction of beta-endorphin concentrations.

Kappa-receptor antagonist reverse 'non-opioid' stress-induced analgesia

We have evaluated the effects of antagonists to the mu, kappa and opiate receptors on 'opioid' and 'non-opioid mediated' analgesia. Our findings indicate that mu receptors might mediate 'opioid' and kappa receptors 'non-opioid' analgesia. It is suggested that endogenous opiates that act on mu or kappa receptors could be responsible for the different types of stress-induced analgesia.

Diclofenac increases beta-endorphin plasma concentrations

Plasma and ventricular cerebro-spinal fluid (CSF) Beta-endorphin concentrations were evaluated after chromatographic separation in patients carrying a ventricular shunt before and after the administration of diclofenac or placebo. In the same subjects the ventricular CSF concentrations of the serotonin and the catecholamine metabolites 5-hydroxyindole-acetic acid (5-HIAA), homovanillic acid (HVA) and MOPEG were also evaluated. Plasma, but not ventricular, Beta-endorphin concentrations increased significantly after diclofenac, while placebo was ineffective. No significant changes in ventricular 5-HIAA, HVA or MOPEG levels were observed. These data suggest a role for Beta-endorphin in the analgesic effect of diclofenac.

[The intravenous nitroglycerin test during coronary angiography]

The effects of intravenous nitroglycerin (Lenitral) on the calibre of coronary arteries and their lesions was studied in 100 consecutive patients undergoing coronary angiography. The coronary arteries were divided into segments (3 for the right coronary, 2 for the left anterior descending, and 2 for the circumflex artery). 510 segments were assessed (279 normal, and 231 pathological). The diameter of each was measured through the mid point before and after injection of a bolus of 0.3 mg nitroglycerin. The calibre of the coronary segments increased in 325 cases (63.7%). In 49 cases, the increase was greater than 50%. It remained the same in 151 cases (29,6%) and decreased in 84 cases (6,7%). The average increase in calibre was 16% (p less than 0.01). This had little relation to the artery under study, the location of the segment or whether the segment was pathological or normal. However, two findings were of interest: - the percentage of segments which increased their calibre was significantly higher in the normal segments (191 out of 279 cases, 68%) than in the pathological segments (134 out of 231 cases, 58%) (p less than 0.01). - Coronary lesions may change in appearance: images of stenosis or obstruction completely regressed in 4 cases, the degree of stenosis seemed to increase in 11 cases because of dilatation of the coronary vessel proximal and distal to the narrowing, and distal vessels appeared much more dilated in 5 cases. The factors which seem to affect the vasomotor response are multiple, and include the state of the arterial wall, the presence of vasodilatation or vasoconstriction prior to injection and the mode of administration of the nitroglycerin. The test should be performed by intravenous or intracoronary injection at the end of coronary angiography so as not to mask spastic phenomena. Some errors in the interpretation of the degree of stenosis or the quality of the distal post-stenotic coronary bed could thus be avoided.

[An approach to the diagnosis of coronary artery spasm in spontaneous angina pectoris (author's transl)]

Spontaneously occurring spasms are more likely to be detected by performing coronary angiography during an acute ischaemic attack. This was achieved in 28 out of 41 cases. Spasm was found to be present in 23/25 attacks with elevated S-T segment but in only 5/16 attacks with other changes on ECG. The difference was statistically significant (p less than 0.01). When coronary angiography was performed outside anginal attacks, arterial spasm was detected in 16 out of 1071 cases (1.48%). The percentage increased in patients with spontaneous angina: 13/15 cases (8.6%). These spontaneous spasms are painless and can be differentiated from catheter-induced spasms and organic stenosis by the nitroglycerin test. Spasms which do not occur spontaneously can be provoked by methylergometrine maleate. This was done 175 time with 16 positive results. The criteria of positivity of the test, as well as its value, indications and dangers are discussed.

[Effects of intravenous trinitrine on myocardial function in left ventricular insufficiency]

The effects of intravenous trinitrin on myocardial function have been studied in 40 patients with heart failure (26 cases of coronary artery disease and 14 of apparently primary cardiomyopathy). Each patient had measurements made of left ventricular pressure, of cardiac output by the dye dilution method, of volume, of the left ventricular ejection fraction, and of the segmental parietal kinetics by means of left side ventriculography both before and after trinitrin. The following results were obtained after injection of trinitrin:--no change in rhythm and cardiac index;--an almost constant decrease in left ventricular end diastolic pressure (38 cases out of 40);--a decrease in arterial pressure and ventricular volume in about two thirds of cases;--improvement of the ejection fraction (25 cases out of 40), and of segmental parietal kinetics (26 cases out of 40) in the left ventricle. These findings were equally true in the patients with coronary artery disease and in the cardiomyopathies. In the light of these results, it appears that when used in left ventricular failure, trinitrin almost always decreases the load, but improves ventricular kinetics only in two thirds of cases, while it has no influence on cardiac output. In addition, given the difficulties in establishing a standard dose of trinitrin, the authors discuss the methods of establishing the optimal dose.

[Criteria of prognosis in apparently primary hypokinetic myocardiopathies (prospective study of 60 cases)]

The fate of 60 cases of apparently primary cardiomyopathy were studied by angiocardiography and coronary arteriography over a 2 to 6 year period, with a mean of 4 years. Correlations were established between the clinical, paraclinical, haemodynamic and angiocardiographic findings on the one hand, and the quality and length of survival on the other. Among the criteria leading to an improved prognosis, the most precise was the left ventricular ejection fraction.

Teaching self-hypnosis to patients with chronic pain

For the past twenty years hypnotherapy and self-hypnosis have been utilized as valid tools for the successful management of severe protracted pain. Control often has been achieved in cases where other modalities of pain management had been inadequate. Hypnosis properly applied can bring some degree of improvement to 90 percent of patients. More remarkable degree of pain relief is achievable in the 25 percent of patients who have high hypnotic "talent," and with very limited expenditure of time and effort. The author discusses basic theories of pain, pain-control pain-control and hypnosis, and he clarifies the effects of physiological, biochemical, and psychological variables which can affect the procedures and the results. Presentation of a clinical case with quoted excerpts of verbalization serves to illustrate the most important points.

[Alcoholic cardiomyopathies (author's transl)]

In 108 patients suffering from congestive type cardiomyopathy, there were 42 alcoholics and 66 non-alcoholics. Comparisons between the two groups were made on the basis of clinical data, paraclinical investigations and prognosis. It was possible to distinguish an alcoholic cardiomyopathy which differs from primary cardiomyopathies by the greater severity of the clinical picture and a gloomier prognosis.

[Venous signs at the acute stage of pulmonary embolism]

The authors have carried out phlebograms on 50 patients with recent pulmonary emboli. In the majority of cases (44 out of 50) they found thrombosis in the veins of the lower limbs: in 35 cases, these were situated proximally, ending in the femoro-ilio-caval segment; in 9 cases they were confined to the suropopliteal veins. These facts have led us to modify our treatment plan for pulmonary embolism. Thrombolytic treatment seems to be justified in cases where the prebitis is high up, even if the pulmonary embolus is benign. Heparin is reserved for those cases of benign pulmonary emboli which are secondary to suro-popliteal phlebitis. The question of interrupting the inferior vena cava must bed ecided in the light of the phlebograms.

[Development of pulmonary embolism]

The authors have made a study of the fate of 118 patients with pulmonary embolism. The mortality (21.8%) is related not only to the embolus itself (especially to the recurrent types) but also to the condition of the affected area. Recurrence is common (34%), serious (9 deaths out of 25), and early (during the first three months.). No treatment or inadequate treatment are the main causes. Treatment works effectively on the pulmonary circulation, which becomes reestablished in the majority of cases, but it carries the risk of a high incidence of haemorrhage (29%) which is severe (2 deaths and 10 tranfusions of more than one litre of blood). In the long term, the prognosis is linked to the developments in the lower limbs, in which there is a progressive failure of venous drainage (46 cases out of 57), even in cases in which there was no local sign of phlebitis at the time of the original embolus.

[Respective value of labelled fibrinogen and rheography in the detection of phlebitis]

The authors have studied in 212 patients the diagnostic value of radio-active fibrinogen and rheography in deep venous thrombosis of the leg by comparing the results from these two methods with phlebography. Radio-active fibrinogen seems the better means of diagnosis in early distal phlebitis. However, the method is expansive, the radio-active substance can only be manipulated in certain specialized centers, and is useless in the presence of hematoma. Rheography is less expansive, more easily manipulated, yet less sensitive as only proximal phlebitis can be detected-especially when completely occlusive. In addition, active patient cooperation is necessary. The time needed to realize the two methods is a major obstacle; however, they can be fruitful if integrated into a specialized department for the diagnosis and treatment of thrombo embolic disease.