Differential effects of beta-endorphin on cAMP levels in human peripheral blood mononuclear cells

In the present paper we demonstrate that one of the early effects of the opioid peptide beta-endorphin on human peripheral blood mononuclear cells is the induction of a change in the intracellular cAMP level. However, the effect of beta-endorphin on cAMP levels is not uniform; increases as well as decreases in cAMP level are observed. It appears that beta-endorphin is a true modulator of intracellular cAMP level: the peptide will increase cAMP levels in cells with a low baseline level. In contrast, beta-endorphin tends to decrease cAMP levels is cells with a high cAMP concentration. Moreover, beta-endorphin modulates the rise in cAMP induced by beta-adrenergic activation. The effect of beta-endorphin on cAMP level correlates negatively with the magnitude of the change in cAMP level induced by beta-adrenergic activation.     

Neurobiological bases for the relation between sleep and depression

The serotoninergic system is involved in the regulation of sleep and wakefulness, its activity being at maximum during the awake state and minimum during sleep. In particular, the production of rapid eye movement (REM) sleep depends on the decrease of serotoninergic tone in brain stem structures. Thus, serotoninergic compounds which increase this tone (such as antidepressants) induce inhibition of REM sleep.Depression is associated with a functional decrease of serotoninergic neurotransmission and with specific alterations of sleep, notably insomnia. Paradoxically, even though they complain of sleep loss, depressed patients exhibit significant mood improvement after one night of sleep deprivation. This antidepressant effect can be accounted for by the same serotoninergic mechanisms as those described for pharmacological treatments. Indeed, the therapeutic action of antidepressants such as selective serotonin reuptake inhibitors is thought to depend directly on the enhancement of central serotoninergic neurotransmission. Such enhancement is achieved through desensitization of serotoninergic autoreceptors, which results from chronic treatment with these compounds. Sleep deprivation also induces an activation of serotoninergic neurons due to prolonged wakefulness, and leads to similar serotoninergic adaptive processes.The common neurobiological mechanisms resulting from pharmacological antidepressant treatment and sleep deprivation suggest that sleep loss in some insomniac or in depressed patients might be an endogenous compensatory process which would be therapeutical rather than pathological. This proposal should open the way to new strategies in the treatment of depression.     

Effects of serotonin on the hypothalamic-pituitary GABAergic system

The effects of serotonin (5-HT) and its precursor, 5-hydroxytryptophan (5-HTP) on the GABAergic system in the mediobasal hypothalamus (MBH) and the anterior pituitary were studied. The IP administration of 5-HTP produced a transient increase (only at 45 min after the injection) in glutamate decarboxylase activity (GAD) of MBH and in GABA concentration in anterior pituitary. Besides, 5-HTP administration increased the in vitro evoked GABA release from MBH. The administration of 5-HTP to hypophysectomized rats partially reversed the inhibitory effects of hypophysectomy on GABA concentration in MBH. We also examined the direct effect of 5-HT on some parameters on the hypothalamic GABAergic system. The presence of 5-HT in the incubation medium increased GAD activity and evoked GABA release from MBH. These observations indicate that the serotoninergic stimulation of the hypothalamic GABAergic system could be a direct effect which may, at least partially, be independent of the feedback mechanism induced by prolactin on the GABAergic neurons. The serotoninergic increase of prolactin secretion could be accomplished through stimulation of the hypothalamic GABAergic transmission.     

Beta-endorphin blunts phosphatidylinositol formation during in vitro activation of isolated human lymphocytes: preliminary report.

We have previously described the regulatory effect of beta-endorphin on three human cytotoxic cell populations. We confirmed the variable nature of these effects on human natural killer cell (NK) activity, showed mixed effects on the generation of cytotoxic T lymphocyte (CTL) activity, and demonstrated the reproducible suppression of lymphokine-activated killer cell (LAK) activity. We and others also observed mixed effects of beta-endorphin on the proliferative response to mitogens and in mixed leukocyte reactions. In the study reported here, we test the effects of beta-endorphin on the formation of phosphatidylinositol during cell activation. 32P-radiolabeled peripheral blood mononuclear cells obtained from normal adult donors and CD2-depleted subpopulations were activated with phytohemagglutinin or in a NK, LAK, or CTL protocol in the absence or presence of recombinant beta-endorphin. The total lipidic extract was analyzed by thin-layer chromatography and autoradiography. The results of these studies indicate that beta-endorphin blunts the formation of phosphatidylinositol by about 20% in the four systems studied and in all the donors tested. This effect is dose-dependent and is blocked in part by the opioid antagonist, naltrexone, suggesting involvement of the opioid receptor.     

Further studies on circadian hormone rhythms after local pharmacological destruction of the serotoninergic innervation of the rat suprachiasmatic region before the onset of the corticosterone rhythm

In previous studies we observed that local pharmacological destruction of the serotoninergic innervation of the hypothalamic suprachiasmatic nucleus before the onset of the circadian plasma corticosterone rhythm interferes with the appearance of the corticosterone rhythm up to the age of two months. In the present investigations we studied other hormone rhythms in such rats and tested animals for corticosterone rhythm when they were older than two months. We found normal circadian fluctuations in plasma testosterone and prolactin levels, variations in growth hormone concentrations, but no changes in plasma corticosterone levels of 63-day-old rats receiving 5,7-dihydroxytryptamine, a neurotoxin selectively destroying the serotoninergic structures, into the suprachiasmatic nucleus at the age of 16 days. Rats did show circadian variations in plasma corticosterone concentrations when tested 3 months after treatment with the neurotoxin. In these latter animals, a significant amount of serotonin-immunoreactive fibers and terminals were evident in the suprachiasmatic nucleus. Only a very few of such elements were seen in rats with a shorter postoperative survival. Our data support the view that serotoninergic innervation of the suprachiasmatic nucleus is essential for the onset of the circadian fluctuations of plasma corticosterone concentrations.     

Serotoninergic innervation of nonprincipal cells in the cerebral cortex of the lizard Podarcis hispanica

The mechanism of serotoninergic transmission in the neo- and archicortex of mammals kis complex, including both synaptic and nonsynaptic components, direct actions on principal cells, and indirect effects mediated by GABAergic interneurons. Here we studied the termination pattern and synaptic organization of the serotoninergic afferents in the cerebral cortex of the lizard, Podarcis hispanica, which is considered to correspond in part to the mammalian hippocampal formation, with the aim of unraveling basic, phylogenetically preserved rules in the connectivity of this pathway. We demonstrate that serotoninergic afferents, visualized by immunostaining for serotonin itself, establish multiple synaptic contacts with different subpopulations of nonprincipal cells containing parvalbumin, neuropeptide Y, and opioid peptides. The former two subpopulations contain GABA, whereas the opioid- immunoreactive neurons are most likely GABA-negative cells. Evidence is provided at the electron microscopic level that serotonin-immunoreactive varicosities establish conventional asymmetric synaptic contacts with their nonprincipal targets, but nonsynaptic varicosities also exist. We conclude that, similarly to mammals, a selective synaptic innervation of nonprincipal, possibly inhibitory, neurons is among the mechanisms of serotoninergic modulation of cerebral cortical activity in the lizard. © 1994 Wiley-Liss, Inc.     

Peripheral mononeuropathy affects hypothalamic and splenocyte beta-endorphin levels but not immune function in the rat

Beta-endorphin and substance P levels were measured in the hypothalamus of rats 14 days after chronic constriction injury of right sciatic nerve. Furthermore, beta-endorphin concentrations in splenocytes, phytoemoagglutinin-induced proliferation of splenocytes, and natural killer activity were assessed. We observed a significant increase of beta-endorphin and substance P hypothalamic levels, and a significant decrease of beta-endorphin concentrations in the immune cells. In contrast, the peripheral mononeuropathy did not affect the immune function. This study presents a picture of central and peripheral peptide changes consistent with a painful condition, but different from what previously observed in rats which underwent peripheral nerve deafferentation or stressful conditions.     

Role of maternal adrenal glands on the developing serotoninergic and aminoacidergic systems of the postnatal rat brain

Serotonin, gamma-aminobutyric acid and glutamate, which are regulated by glucocorticoids in the central nervous system, are involved in neuroendocrine functions and the development of the brain. The present study investigates the effect of maternal adrenalectomy on the developing serotoninergic, GABAergic and glutamatergic systems. Neurotransmitter levels were measured in four brain areas of both male and female offspring on postnatal days 1, 8, 12 and 22. At postnatal day 1 and 8, the pups of adrenalectomized dams showed higher concentrations of serotonin than controls in all the brain areas studied. Serotonin levels decreased significantly in males at postnatal day 22 in the hippocampus and cortex. During the first 2 weeks of postnatal life, the lack of maternal corticosterone produced an increase in glutamate and a reduction in gamma-aminobutyric acid concentrations, mainly in males. Further, on postnatal day 1, increased serotonin and glutamate levels and lower levels of gamma-aminobutyric were observed in the hypothalamus of male pups born to adrenalectomized dams. The absence of maternal corticosterone affects the pattern of development of the serotoninergic system, especially in the hippocampus and cortex, and particularly in males. A delay in the maturation of the aminoacidergic systems, mainly of the GABAergic system and in males, was also seen. A sexually dimorphic response to the removal of maternal glucocorticoids was seen in terms of neurotransmitter levels, mainly in the hippocampus and hypothalamus.     

Interactions between GABAergic and serotoninergic systems with excitatory amino acid neurotransmission in the hypothalamic control of gonadotropin secretion in prepubertal female rats

The present studies were designed to study the interrelationships between GABAergic, serotoninergic and excitatory amino acids systems (EAAs) in the control of gonadotropin secretion in prepubertal female rats. For this purpose we determined the effects of N-methyl-d-aspartate (NMDA), an exogenous agonist of EAAs receptors, on LH and FSH secretion in 16-day-old female rats in which the GABA-A and GABA-B receptors were blocked by bicuculline and baclofen or serotonin (5-HT) depleted by p-choloroamphetamine (PCA). In addition the effects of the GABAergic and serotoninergic systems on LH and FSH secretion were evaluated in animals treated with dibenzocycloalkenimine (diocilpine MK-801), an antagonist of NMDA neurotransmission. While muscimol, a GABA- A agonist, induced a significant increase in LH and FSH levels (P<0.01), baclofen, a GABA-B agonist, had an inhibitory effect on these hormones (P<0.01). MK 801, a NMDA receptor antagonist, not only suppressed the stimulatory effect of NMDA on LH and FSH but also blocked the stimulatory effect of muscimol without modifying the inhibitory action of baclofen on both gonadotropins. Bicuculline, a GABA-A receptor antagonist, did not modify the release effect of NMDA on LH and FSH. 5-HTP, a precursor of 5-HT that increases the levels of this neurotransmitter in the central nervous system significantly increased (P<0.01) the plasma levels of LH and FSH, and this effect was blocked by the NMDA receptor antagonist MK-801. We conclude that the stimulatory effects of GABAergic and serotoninergic systems in prepubertal female rats are connected with the activation of EAA neurotransmission, while the stimulatory effects of NMDA appear to be independent of serotoninergic and GABAergic actions on LH and FSH secretion. Since both GABA and serotonin systems change their effects on LH and FSH during sexual maturation from a stimulatory action in prepubertal to an inhibitory action in adult rats and since NMDA neurotransmission has a stimulatory effect on gonadotropin secretion both in prepubertal and adult rats, it is clear that the interrelationships between GABAergic and serotoninergic systems with EAAs in the gonadotropin control are different in prepubertal and in adult rats.     

Analysis of the Inhibitory Effect of Oestradiol on Functional GABA/5-HT Relationship in the Rat Suprachiasmatic Area

The purpose of this study was to test the capacity of oestradiol to modulate the stimulating effect of a-aminobutyric acid (GABA) on serotonin (5-HT) metabolism, previously described in the Suprachiasmatic area of the male rat. After an in vivo stimulation of GABA transmission by systemic administration of a GABA-transaminase inhibitor (amino-oxyacetic acid) or a GABA_B agonist (RS-baclofen), the 5-HT metabolism was studied in the Suprachiasmatic area of ovariectomized, and ovariectomized oestradiol-treated rats. Amino-oxyacetic acid or RS-baclofen treatment increased the endogenous content of 5-HT in the Suprachiasmatic area of males and ovariectomized rats. These two treatments were without effect in ovariectomized oestradiol-treated rats. GABA transmission stimulation induced by amino-oxyacetic acid treatment failed to affect the release and synthesis of 5-HT in ovariectomized oestradiol-treated rats while it increased these two parameters of 5-HT metabolism in the Suprachiasmatic area of male and ovariectomized rats. To investigate the main target of oestradiol effect, comparative studies of the serotoninergic and GABAergic metabolism in the Suprachiasmatic area were performed in the three experimental groups. Under our experimental conditions the endogenous 5-HT metabolism was similar between ovariectomized and ovariectomized oestradiol-treated rats. Nevertheless, 5-HT metabolism was higher in the two female groups than in the male group. Neither GABA metabolism nor GABAergic response to GABA-related drug treatment differed between ovariectomized, and ovariectomized oestradiol-treated rats. However, the turnover of GABA was higher when compared to the two female groups. It is concluded that the lack of 5-HT responsiveness to GABA transmission stimulation in ovariectomized oestradiol-treated rats was not related to an effect of oestradiol on 5-HT metabolism or to an effect of the steroid on GABA turnover. Furthermore, our results suggest a sex difference in the activity of serotoninergic and GABAergic systems in the Suprachiasmatic area.     

Opiate receptor-mediated chemotaxis of human monocytes

The opiate peptides, D-ala-D-leuenkephalin, beta-endorphin and dynorphin, [1-13] are potent stimulators of human mononuclear cell chemotaxis. Peak responses were observed in the range of 10(-8) - 10(-11)M with activity detectable at 10(-14)M. Morphine was without effect in this assay. Incubation of cells with (-) naloxone but not (+) naloxone completely blocked activity, supporting stereospecific opiate receptor-mediated chemotaxis. Opiates and other neuropeptides are discussed as components of a network whose purpose is to integrate brain and behavioral modalities with immune function.     

Beta-endorphin decline in late luteal phase dysphoric disorder

The beta-endorphin hypothesis of late luteal phase dysphoric disorder (premenstrual syndrome or L2D2) was tested. Twenty-two PMS patients were compared to twenty-two controls. Levels of beta-endorphin, ACTH, FSH, LH, cortisol, prolactin and TRH were measured on the first and twentieth days after menses. PMS subjects exhibited a significantly greater drop in the opiate, beta-endorphin, (p less than .001) than controls. No relationship or significant e was seen with the other hormones/transmitters tested. The symptoms of PMS may be due to noradrenergic rebound following beta-endorphin decline. Symptomatic and pharmacological morphine withdrawal and manic phase of bipolar disorder are discussed as possible models for L2D2.     

Brain β-endorphin concentrations in experimental chronic liver disease

β-Endorphin, Met-enkephalin, substance P and somatostatin concentrations have been evaluated in brain areas of rats with severe liver disease obtained by chronic pretreatment with CCl₄ for 3 or 9 weeks. β-Endorphin, but not Met-enkephalin, somatostatin or substance P concentrations were significantly decreased in the hypothalamus of both the three and nine week-treatment groups. The β-endorphin decrease we observed might be tentatively attributed to a modification of GABA levels, but not serotonin, since the stimulation of the serotoninergic system induced a significant increase, while the potentiation of the GABAergic system induced a clear decrease of β-endorphin concentrations in the hypothalamus of treated rats.     

人脐血单个核贴壁细胞与胃癌细胞的共培养：最适效靶比筛选***☆

背景：近年来大量研究关注脐血细胞可能对肿瘤细胞有杀伤和抑制作用，人们尝试利用脐血细胞移植抑制和杀伤肿瘤细胞，这为临床医生们提供了抗癌的新途径。 目的：探讨人脐血单个核细胞与肿瘤细胞体外共培养后，对肿瘤细胞的抑制作用。 方法：采用密度梯度离心的方法分离人脐血单个核细胞，流式检测细胞表面Marker表达，将单个核细胞与胃癌细胞进行共培养，倒置显微镜观察两种细胞共培养后细胞形态的变化，采用了乳酸脱氢酶法检测对肿瘤细胞的抑制作用，找出抗肿瘤细胞效果最好的效靶比。 结果与结论：加入脐血的贴壁单个核细胞贴壁细胞2 d后，肿瘤细胞的脱落明显，贴壁细胞实验组肿瘤细胞排列不规整，细胞密度低。酸脱氢酶法显示部分脐血贴壁细胞确有较强的抗肿瘤能力，但个体间抗肿瘤的能力差异较大，最大可相差4倍。脐血单个核贴壁细胞对肿瘤细胞有直接的杀伤作用，其最适的效靶比为2:1。     

Release of immunoreactive Met-enkephalin from the spinal cord by intraventricular beta-endorphin but not morphine in anesthetized rats

Effect of beta-endorphin and morphine injected intraventricularly on the release of immunoreactive Met-enkephalin, Leu-enkephalin and dynorphin1-13 from the spinal cord was studied in anesthetized rats. Intraventricular beta-endorphin, 16 micrograms, caused a marked spinal release of immunoreactive Met-enkephalin and to a much lesser extent, of immunoreactive Leu-enkephalin while intraventricular morphine, 40 micrograms, did not cause any significant release of immunoreactive enkephalins. The release of immunoreactive Met-enkephalin was not blocked by the pretreatment with 5 mg/kg naloxone, i.p. Immunoreactive dynorphin1-13 was not released by either beta-endorphin or morphine. High performance liquid chromatographic analysis indicated that immunoreactive Met-enkephalin released by beta-endorphin had a retention time identical to [3H]Met-enkephalin. These findings in conjunction with previous pharmacological studies suggest different modes of pharmacological action for beta-endorphin and morphine.     

Plasma beta-endorphin and natural killer cell activity in major depression: a preliminary study.

Low concentrations of beta-endorphin have been found to enhance human natural killer (NK) cell activity in vitro. Both beta-endorphin and NK activity are changed by clinical depression. To evaluate whether circulating concentrations of beta-endorphin have a role in the in vivo modulation of cellular immunity in humans, we measured plasma beta-endorphin and NK cell activity in 14 depressed patients and 14 age-matched control subjects. In the depressed patients, both plasma beta-endorphin and NK cell activity were reduced to 76% and 57%, respectively, of the mean levels in the control subjects. In addition, beta-endorphin showed a significant positive correlation with lytic units of NK cell activity in the combined group of all subjects and in the patient group (p = 0.04), but not in the control group. The study supports the hypothesis that circulating endorphin is correlated with NK cell activity in vivo. This correlation may be higher in the depressed patient group.     

Delayed effects of chronic cortisol treatment on brain and plasma concentrations of corticotropin (ACTH) and beta-endorphin

The effects of 2-day and 7-day cortisol treatment on immunoreactive corticotropin (ACTH) and beta-endorphin concentrations were measured in the cerebral cortex, hippocampus, hypothalamus, and cerebellum in male rats. Plasma ACTH, beta-endorphin, corticosterone, and cortisol levels were also measured in parallel. Cortisol administration by osmotic minipumps (25 mg/kg/day) maintained a constant, moderately high concentration (23.0 +/- 2.7 micrograms/100 ml) of this glucocorticoid in plasma. Two-day cortisol treatment suppressed the plasma concentration of ACTH and corticosterone, and also decreased, to a lesser degree, concentrations of beta-endorphin. ACTH and beta-endorphin levels in the brain remained unchanged after 2 days of cortisol treatment. After 7-day treatment, however, plasma concentrations of ACTH and beta-endorphin further decreased, while ACTH and beta-endorphin concentrations in the cortex and beta-endorphin concentrations in the cerebellum were also significantly decreased. Peptide concentrations in other brain areas did not change significantly with either 2-day or 7-day cortisol treatment. These data suggest that there are delayed effects of glucocorticoids on pro-opiomelanocortin peptide secretion and/or metabolism in the central nervous system. These findings are consistent with the impaired cognitive functions of patients with diseases, such as Cushing's syndrome and depression, that have long-lasting elevated cortisol secretion.     

Effects of hypophysectomy and dexamethasone treatment on plasma beta-endorphin and pain threshold during pregnancy

During pregnancy, rats and humans show an increase in pain threshold that is mediated by an endorphin system. In order to determine whether plasma beta-endorphin and/or other factors of pituitary origin are involved in pregnancy-induced analgesia in the rat, the effects of hypophysectomy (day 12 of pregnancy) or pharmacological suppression of pituitary function via dexamethasone administration (day 14-21 of pregnancy) were investigated. Hypophysectomy did not affect either the magnitude of the increase or the pattern of change in pain threshold despite the resulting decrease in stress-induced plasma beta-endorphin concentrations. However, the observed effect of the surgical and/or postsurgical procedure on pain threshold confounded unequivocal interpretation of these results. Pharmacological suppression of pituitary function with dexamethasone (2 micrograms/ml), a non-invasive procedure, also produced a significant decrease in resting plasma beta-endorphin levels. As was observed for surgical removal of the pituitary gland, this treatment did not produce a significant alteration in the magnitude of the increase in jump threshold. Furthermore, no correlation was found between plasma beta-endorphin concentrations and jump threshold values on day 21 of pregnancy. These results indicate that the pituitary gland does not play an essential role in the maintenance of opioid analgesia during pregnancy. It is suggested that pregnancy-induced analgesia depends on central rather than peripheral opioid systems.     

Effect of Naloxone on the Secretion of Corticosterone Induced by Gamma-Hydroxybutyric Acid in Male Rats

The effect of intraperitoneally administered γ-hydroxybutyrate on the hypothalamo-hypophysial-adrenocortical axis was studied. A significant increase in plasma corticosterone was induced by the administration of γ-hydroxybutyrate (100 mg/kg). The lack of antagonism of this action of γ-hydroxybutyrate by picrotoxin or bicuculline pretreatments (GABAergic antagonists), suggests independence from the GABAergic system. Neither dopaminergic nor serotoninergic systems intervened in the γ-hydroxybutyrate-stimulating effect on the hypothalamo-hypophysial-adrenocortical axis. Both corticosterone release and synthesis in adrenocortical cells was not significantly affected by γ-hydroxybutyrate, suggesting that this is possibly due to a central action of γ-hydroxybutyrate. The increase in corticosterone levels was probably mediated by an opioid receptor, since a strong similarity existed between the effects of γ-hydroxybutyrate and those of morphine. Moreover, the results show that the opioid-receptor involvement was demonstrated by the naloxone-sensitivity of the γ-hydroxybutyrate effects.