Interleukin regulation of prolactin and corticotropin from pituitary adenoma

Recent findings indicate that lymphokines, leukocyte-derived hormones, interact with the hypothalamic-pituitary axis. We examined the role of neurotrophic lymphokines in the neuroendocrine system. Specifically, the action of Interleukin (IL)-1b, IL-2 and IL-6 upon the anterior pituitary hormones, growth hormone (GH), prolactin (PRL) and adrenocoticotropic hormone (ACTH) were studied in rodent pituitary adenoma cell lines. Hormone release by GH and PRL-producing rat adenoma cells (GH3) and ACTH-producing mouse adenoma cells (AtT-20) was analyzed by radioimmunoassay (RIA). Recombinant (r) IL-1beta decreased PRL release from GH3 in a dose-dependent fashion. IL-1 inhibition of PRL production occurred in parallel with IL-1 inhibition of DNA synthesis in GH3 as measured by [(3)H] thymidine incorporation. This result strongly indicates that IL-1 alters PRL production by adenoma cells at the translational level. Low dose IL-2 (10 U/ml) enhanced ACTH production from AtT-20, but higher concentrations of IL-2 failed to affect the release of ACTH. IL-2 did not change the incorporation of [(3)H] thymidine in AtT-20. Previous studies showed that IL-1 and IL-6 induce a significant secretion of ACTH via the hypothalamic-pituitary axis. However, IL-1 and IL-6 failed to affect ACTH secretion by AtT-20. Blood-derived cytokines have direct effects on hormone secretion by pituitary adenoma cells in vitro.     

Vasoactive intestinal peptide can modulate immune and endocrine responses during lipopolysaccharide-induced acute inflammation

OBJECTIVES: In many studies, it has been reported that vasoactive intestinal peptide (VIP) may play an important role in modulation of the immunological response. VIP can be produced by immunological cells, and also the receptors for this neuropeptide are present in many of these cells. The aim of our study was to estimate the effects of the administration of exogenous VIP on serum concentrations of proinflammatory cytokines [interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha] and an anti-inflammatory cytokine (IL-10) during lipopolysaccharide (LPS)-induced acute inflammation. We also estimated the influence of VIP on pituitary [FSH, LH, TSH and prolactin (PRL)], thyroid (T3 and T4), adrenal (corticosterone) and gonadal (testosterone) hormones in response to LPS-induced acute inflammation. METHODS: Male Wistar-Kyoto rats were divided into four groups, which received, respectively, placebo (0.9% NaCl), LPS, VIP and VIP with LPS. The TNF-alpha and IL-6 serum concentrations were measured after 2 h from the time of the administration of the agents, IL-10 was measured after 4 h, and the pituitary, thyroid, adrenal and gonadal hormone concentrations were measured after 2 and 4 h. Cytokine concentrations were estimated using ELISA tests, and hormone concentrations were measured using RIA tests. RESULTS: In our experiments, LPS administration dramatically increased serum proinflammatory cytokine concentrations (TNF-alpha and IL-6) after 2 h and the anti-inflammatory cytokine (IL-10) after 4 h, as well as increasing the serum corticosterone concentration (after 2 and 4 h) and LH (after 2 h). LPS application decreased serum concentrations of T3 and TSH (both after 2 h), testosterone (after 2 and 4 h), FSH after 4 h and PRL after 4 h. VIP administration decreased the serum IL-10 concentration after 4 h and T3 concentration after 2 h and increased serum concentrations of FSH and corticosterone after 4 h. VIP administrated simultaneously with LPS decreased the LPS-induced increase in IL-6 and corticosterone concentrations (consecutively after 2 and 4 h). VIP also enhanced LPS-induced thyroid hormone (T3 and T4) suppression after 4 h and testosterone suppression after 4 h. CONCLUSION: We conclude that VIP can modulate not only immune responses but also hormonal responses during acute inflammation.     

Differential Response of Growth Hormone, Cortisol, and Prolactin to Seizures and to Stress

Plasma concentrations of growth hormone (GH), cortisol, and prolactin (PRL), following a spontaneous generalized seizure in epileptic men were compared with similar measurements made in nonepileptic, stressed men to determine the role of stress in the hormonal response to seizures. Nonepileptic, nonstressed men served as control subjects. GH concentrations increased significantly within 60 min postictally, and as expected, so did cortisol and PRL. A subgroup of alcoholic patients exhibited a smaller GH response to seizures. Stressed patients had significantly less elevated cortisol and PRL plasma values, but no rise of GH. The data suggest that neurogenic stimuli responsible for the postictal release of GH, cortisol, and PRL are, at least in part, independent of stress mechanisms and that GH response is blunted in alcoholic patients.     

Shock-induced modulation of lymphocyte responsiveness and natural killer activity: differential mechanisms of induction

The present study was designed to determine the influence of signaled shock on splenic natural killer (NK) activity and nonspecific T-lymphocyte mitogenic responsiveness. Furthermore, experiments were conducted to examine possible mechanisms mediating this suppression. The results demonstrate that a single session of signaled shock induces suppression of splenic NK activity and T-cell response to the mitogens concanavalin A (Con A) and phytohemagglutinin (PHA). However, the suppression of mitogenic responsiveness was attenuated after five daily sessions of shock, while NK activity remained suppressed. The suppression of NK function was prevented by administration of naltrexone prior to the shock session indicating mediation by opiate receptors. However, naltrexone did not prevent the shock induced suppression of mitogenic responsiveness to Con A or PHA. Diazepam was not effective in preventing the shock-induced suppression of mitogenic responses or NK activity. Collectively, these results demonstrate that mononuclear cell populations in the spleen are differentially affected by the same stressor and that the immune alterations are mediated via different pathways.     

Prolactin receptors on large granular lymphocytes: dual regulation by cyclosporin A

Although evidence has been provided for a modulatory role of prolactin (PRL) on humoral and cell-mediated immune responses and PRL receptors have been found on T and B lymphocytes, no indications exist concerning the influence of PRL on natural killer (NK) activity nor has a structural basis for interaction been found on the NK effector cells (large granular lymphocytes, LGL). We show here that highly purified LGL express binding sites for PRL. The calculated receptor number was 660 per cell and the dissociation constant (Kd) was 3.0 X 10(-10) M. Since previous studies have reported that cyclosporin (CsA), an immunosuppressive agent used in organ transplant patients, affects the binding of PRL to T and B lymphocytes, but not to rabbit mammary gland cells, we investigated whether this compound could alter the binding of the hormone to LGL. At concentrations from 10(-7) to 10(-6), corresponding to the therapeutical range, CsA induced a complete inhibition of the PRL binding. By contrast, concentrations of CsA ranging from 10(-11) to 10(-9) increased the PRL binding to more than 100% of control levels. In addition to their antitumor role, LGL have been proposed to participate in graft versus host disease and in transplant rejection. The finding that CsA can differently affect PRL-receptor expression on LGL points to an involvement of CsA--PRL interactions in determining the output of these immune responses. In addition, these data strongly support the idea of a close relationship between the neuroendocrine and immune systems.     

Mitogen-stimulated lymphocyte proliferation and pituitary hormones in major depression

To assess cellular immune status and the hypothalamic-pituitary (HP) axis in patients with major depression, we examined peripheral blood mononuclear cells (PBMC) and measured the plasma levels of cortisol, adrenocorticotropin hormone (ACTH), growth hormone (GH), and prolactin (PRL). Twenty patients with major depression were compared with 20 control subjects matched for age, sex, and race. The dose-response curves for concanavalin-A (Con-A) and phytohemagglutinin (PHA) stimulation were not significantly different between the two groups. The patients had decreased Con-A-stimulated T-lymphocyte proliferation when compared to the control subjects, but only at the lowest suboptimal concentration of Con-A. None of the four concentrations of PHA-stimulated proliferation were different between the two groups, neither was PHA-induced interleukin-2 production. Within the patient group only, plasma prolactin (PRL) correlated significantly with stimulated lymphocyte proliferation using two optimal concentrations of PHA and one optimal concentration of Con-A, when the proliferation was expressed using the stimulation index.     

Immunologic Aspects of Carbamazepine Treatment in Epileptic Patients

Immune abnormalities have been found in epileptic patients receiving antiepileptic drugs (AEDs). Phenytoin (PHT) produces a decrease in serum IgA and IgM levels and a decrease in blastic transformation of circulating lymphocytes stimulated with phytohemoagglutinin (PHA). The effects of carbamazepine (CBZ) on the immune response are still conflicting. To elucidate the effects of CBZ on some immunologic parameters, serum concentrations of IgA, IgG, IgM, the phagocytosis and killing properties of polymorphonuclear leukocytes (PMNs), the cytotoxic activity of natural killer cells and the response of lymphocytes to mitogenic agents were studied. Forty healthy individuals and 39 epileptic patients treated with carbamazepine (CBZ) monotherapy (age range 18-40 years) entered the study. Student's t test was used to evaluate the data. CBZ had no effect on the serum immunoglobulin concentrations or on lymphocytic reactivity to phytohemoagglutinin (PHA) mitogen. CBZ produced a significant enhancement of phagocytosis and killing properties of PMNs and an increase in natural killer (NK) cell activity. Therefore, a negative effect of CBZ therapy on the immune system was not observed in this study.     

Stimulation by mitogens and neuronal membranes of lymphocytes from patients with motor neurone disease

Stimulation of lymphocytes from motor neurone disease patients by either concanavalin A or PHA was shown to be significantly depressed relative to that from normal controls, as assayed by incorporation of [3H]thymidine or [3H]leucine or by glucose uptake. Corresponding significant differences were not shown by assays based upon incorporation of [3H]uridine or of lactate release. Lymphocytes from 4 out of 14 motor neurone disease patients showed a blastogenic response to membranes from rat spinal cord cells, compared with those from 0 out of 9 normal controls. These results not only suggest the possibility of an impaired cellular immune control in MND patients but also indicate the presence of lymphocytes sensitised specifically to neuronal membrane components.     

The action of halothane on stimulus-secretion coupling in clonal (GH3) pituitary cells

The effect of halothane on the physiological response to excitatory stimuli was assessed in clonal (GH3) pituitary cells. Halothane, at concentrations used to produce general anesthesia in animals (0.25-0.76 mM), inhibited thyrotropin-releasing hormone (TRH)-induced prolactin (PRL) secretion. The sustained (extracellular calcium-dependent) phase of PRL secretion was 70 +/- 7% inhibited by the highest concentration of halothane tested (0.76 mM); 50% inhibition was produced by approximately 0.4 mM halothane. The early (largely inositol trisphosphate-mediated) phase of secretion was less sensitive to halothane; 0.76 mM halothane produced 18 +/- 2% inhibition of the early phase of secretion. Consistent with these observations, halothane inhibited (IC50 approximately 0.45 mM) the sustained phase of the TRH-induced rise in intracellular calcium ([Ca2+]i) to a greater extent than the initial [Ca2+]i peak. The sustained phase of the [Ca2+]i elevation was inhibited by 75 +/- 7% at the highest concentration of halothane tested (0.76 mM), whereas the peak [Ca2+]i was only inhibited by 14 +/- 5%, consistent with the observation that halothane did not inhibit TRH-stimulated inositide hydrolysis in these cells. Halothane (0.5 mM) did not inhibit phorbol ester- or ionomycin-induced PRL secretion, indicating that halothane has inconsequential effects on the secretory apparatus. Halothane (0.5 mM) also inhibited KCl-induced PRL secretion by 50-80% and the corresponding KCl-induced rise in [Ca2+]i by 68 +/- 6%. These data indicate that halothane inhibits secretagogue-stimulated PRL secretion by reducing the elevation of [Ca2+]i produced by calcium (Ca2+) influx.(ABSTRACT TRUNCATED AT 250 WORDS)     

Immunologic Aspects of Vigabatrin Treatment in Epileptic Children

Summary Vigabatrin (VGB) is an antiepileptic drug (AED) that acts by irreversibly inhibiting γ-aminobutyric acid transaminase (GABA-T). To evaluate immune responses to GVG, we studied 29 idiopathic or symptomatic epileptic children and also examined a control group (n = 15). Epileptic children were tested before and after 1 and 3 months of VGB treatment. Whole blood was used to connect subsets with commercial monoclonal antibodies. Peripheral blood mononuclear cells (PBMC) were used to assess natural killer (NK) cell activity and lymphocyte response to phytohemagglutinin (PHA) and concavalin A (Con A). Immunoglobulin (Ig) levels were tested in serum. At baseline, no immunologic abnormalities were observed in either control or treated patients. During treatment, the percentage and absolute number of B lymphocytes, serum concentration of Ig, number of T total mature lymphocytes (CD3), T-rosetting lymphocytes (CD11), T-helper cells (CD4), and mitogenic response of lymphocytes remained unchanged. Several other immunologic responses showed a statistically significant increase after 1 and 3 months of VGB treatment, however, including the percentage and absolute number of T-suppressor cells (CD8) and NK cells and NK cell activity. The correlation between number of NK cells and NK cell activity was significant. Data obtained demonstrated that VGB may interfere with the modulation of the immune system, especially cytotoxic cell populations.     

Impaired Neuroendocrine and Immune Response to Acute Stress in Medication-Naive Patients With a First Episode of Psychosis

Little is known about how the biological stress response systems—the autonomic nervous system (ANS), the hypothalamic-pituitary-adrenal (HPA) axis, and the immune system—function during psychosis. Results of studies on the effect of stress on the immune and autonomic system in patients with schizophrenia are inconsistent. The present study investigates whether the stress response is impaired in medication-naive patients with a first episode of psychosis. Ten male patients with a first episode of psychosis and 15 controls were exposed to the stress of public speaking. Parameters of the ANS (heart rate and catecholamines), the HPA axis (plasma adrenocorticotropic hormone [ACTH] and cortisol), and the immune system (number and activity of natural killer [NK] cells) were measured. Peak responses were calculated to examine the relationship between stress-induced activation of the different systems. Subjective stress and anxiety before and during the task were assessed. Patients and controls displayed similar autonomic responses to acute stress. However, there was an impaired HPA axis response, slow onset and return of ACTH, and flattened cortisol response and a reduced increase in number NK cells and NK cell activity in patients with a first episode of psychosis. Furthermore, in patients, the relationship between the different stress response systems was weaker or absent compared with controls. These findings indicate that impairments in stress processing are associated with the endophenotype of psychosis and are not a result of illness progression or antipsychotic medication.     

Prolactin stimulates maturation and function of rat thymic dendritic cells

The current study analyses the effect of PRL, a hormone involved in numerous physiological processes, on dendritic cells (DC) of rat thymus. Most thymic DC express prolactin receptors (PRL-R) as demonstrated by both immunohistochemistry and flow cytometry. PRL administration during 2 or 6 days to fetal thymus organ cultures (FTOC) does not increase the proportions of DC in cultures but stimulates their differentiation. Furthermore, PRL-treated thymic DC exhibit increased allostimulatory capacity in mixed leukocyte reaction (MLR) assays in association with increased surface expression of both MHC antigens and the co-stimulatory molecule CD80. PRL-treated DC also produce increased amounts of pro-inflammatory cytokines, such as IL-12, TNFalpha and IL-1beta, but not of IL6 or IL-10. Our data suggest a key role for IL-12 in the observed changes in the allostimulatory capacity of PRL-treated DC. Also, they permit us to hypothesize about the physiological role played by PRL in thymus ontogeny.     

Muscarinic M1 and M3 receptors are present and increase intracellular calcium in adult rat anterior pituitary gland.

Physiological and biochemical evidence indicates the existence of functional muscarinic cholinergic receptors in the anterior pituitary. The selectivity of these receptors has been characterised by studying the binding of [3H]quinuclidinyl benzilate ([3H]QNB) and [3H]diphenyl-acetoxy-N-methyl-piperidine ([3H]4-DAMP) in membrane preparation of male rat anterior pituitary at 25 degrees C. Competition experiments with receptor selective muscarinic antagonists were used to characterise specific selective muscarinic receptor binding. Both [3H]QNB and [3H]4-DAMP bound to anterior pituitary membranes at low concentrations, binding was saturable and was potently displaced by 4-DAMP (M1, M3 subtypes selective antagonist) > atropine (general) > pirenzepine (M1). Methoctramine (M2) didn't antagonise the [3H]QNB binding efficiently. Acetylcholine and carbachol increased the intracellular Ca2+ level in 62% and 65% of cultured rat anterior pituitary cells in a dose-dependent manner, and this effect was prevented by pirenzepine. Based on these results we suggest that both M1 and M3 muscarinic receptors are present and active in the majority of cells in the rat anterior pituitary gland, but their physiological role in the adult rat remains to be examined.     

Ischemic-like condition releases norepinephrine and purines from different sources in superfused rat spleen strips

Transmitters and cotransmitters of the sympathetic nervous system are involved in the regulation of a variety of immune cell functions. However, it is not entirely clear what stimuli lead to the release of these molecules in immune organs. In this study, we investigated whether local ischemia can cause the parallel release of norepinephrine and its cotransmitter, ATP, in the spleen. Ischemic-like conditions, simulated by transient (15 min) O(2) and glucose deprivation, elicited a reversible increase in the release of both norepinephrine and purines from superfused spleen strips preloaded with [3H]norepinephrine or [3H]adenosine. HPLC analysis of the released tritium label revealed a net increase in the amount of ATP, ADP, AMP, adenosine, inosine, hypoxanthine and xanthine in response to ischemic-like condition. Selective O(2) or glucose deprivation, and Ca(2+)-free conditions differentially affected the outflow of [3H]norepinephrine and [3H]purines, indicating that they derived from different sources. The ABC transporter inhibitors glibenclamide (100 microM) and verapamil (100 microM) as well as low-temperature inhibited [3H]purine release evoked by ischemic-like conditions. Surgical denervation of the spleen reduced endogenous catecholamine content and [3H]norepinephrine uptake of the spleen, but not that of [3H]adenosine. In summary, these results demonstrate the release of norepinephrine and purines in response to an ischemic-like condition in an immune organ. Although both could provide an important source of extracellular catecholamines and purines involved at various levels of immunomodulation, the source and mechanism of norepinephrine and purine efflux seem different.     

Role of Adrenoceptors in Vasopressin, Oxytocin and Prolactin Responses to Conditioned Fear Stimuli in the Rat

Conditioned fear or novel environmental stimuli suppress vasopressin (VP) and augment oxytocin (OT) and prolactin (PRL) release in rats. We examined the effects of intracerebroventricular (i.c.v.) injections of adrenoceptor antagonists on these neuroendocrine responses to conditioned fear or novel environmental stimuli in male rats. A β 1 antagonist, metoprolol, blocked the VP but not the OT or PRL response to conditioned fear stimuli, but did not abolish neuroendocrine responses to novel environmental stimuli. A β 2 antagonist, ICI118551, impaired the PRL but not the VP or OT response to fear or novel environmental stimuli. In rats injected with a α 1 adrenoceptor antagonist, benoxathian, conditioned fear stimuli did not significantly induce the VP, OT or PRL responses. The effects of benoxathian were not due to a general reduction of arousal, since benoxathian did not prevent the VP, OT or PRL response to novel environmental stimuli. These data suggest that β 1 adrenoceptors play a selective role in the VP response to conditioned fear stimuli, as do β 2 adrenoceptors in the prolactin response to conditioned fear and novel environmental stimuli. We conclude that α 1 adrenoceptors play a facilitative role in VP, OT, PRL responses to conditioned fear stimuli.     

Absence of preproenkephalin increases the threshold for T cell activation

Certain forms of the neuroendocrine hormone preproenkephalin (PPNK) are produced by T cells, B cells and macrophages. This hormone has been shown to be important in regulating a variety of immune responses; however, the basic mechanisms of this regulation are unknown. Here we examine the ability of CD8 and CD4 PPNK-deficient T lymphocytes to proliferate to antigenic and mitogenic stimuli. We found that lymphocyte activation and proliferation to suboptimal concentrations of both anti-CD3 and antigen was reduced in the absence of PPNK. Proliferation could be rescued by increasing antigen or by co-incubation of PPNK-deficient cells with wild-type cells. These data confirm the importance of neuroendocrine hormones such as PPNK in T cell activation and proliferation and provides a potential mechanism for the regulation of T cell responses by PPNK or its peptide derivatives.     

IL-1β and IL-10 have dual effects on enteric glial cell proliferation

Inflammatory bowel disease is typically accompanied by functional and structural changes of the enteric nervous system. In pathological studies, cellular loss and axonal degeneration have been described in the myenteric plexus. However, more recent studies suggest that the proliferation rate of myenteric glial cells is enhanced in animal models of intestinal inflammation. Therefore, we have investigated the effect of different cytokines on the proliferative response of enteric glial cells (EGCs), comparing transformed enteric glial cell lines, primary astrocyte cultures and transformed oligodendrocytes. Cells were incubated in serum-free chemically defined medium in the presence or absence of either interleukin (IL)-1beta or IL-10 at concentrations ranging between 0.1 and 100 ng mL(-1) for 48 h. Subsequently, [3H]thymidine was added to each culture dish for an additional 6 h, and the amount of incorporated [3H] was assessed. IL-1beta significantly and dose-dependently suppressed [3H]-uptake by EGCs. In contrast, IL-10 induced a biphasic response; IL-10 at low concentrations (0.1 ng mL(-1)) caused a significant suppression of [3H]-uptake, whereas high concentrations (5-100 ng mL(-1)) significantly enhanced [3H] uptake. These results indicate that EGC proliferation can be modulated by cytokines. The differential effects of IL-1beta and IL-10 suggest that during intestinal inflammation there may be a regulatory interplay between different classes of cytokines modulating EGC proliferation.     

Ganglioside synthesis and transport in regenerating sensory neurons of the rat sciatic nerve

The sciatic nerves of rats were crushed with fine forceps and allowed to survive for 3 or 7 days, at which time the 5th lumbar dorsal root ganglion was injected with [3H]glucosamine. Animals were killed 18 h later and the nerves proximal and distal to the crush site were cut into 3 mm segments. Gangliosides were purified from these segments, and radioactivity was separately measured in gangliosides, neutral glycolipids and glycoproteins. For all 3 fractions, radioactivity was distributed similarly between the crush site and point of maximum axonal elongation. A second smaller peak of ganglioside radioactivity was seen to span a few segments immediately distal to the point of maximum axonal elongation. We propose two possible explanations for this: (1) it represents ganglioside synthesis by Schwann cells (from blood-borne [3H]glucosamine) as part of the mitogenic response of these cells to the reappearance of axons; or (2) recently synthesized, transported gangliosides are released from the growth cone and taken up by adjacent mitogenic Schwann cells.     

Immunomodulatory effects of footshock in the rat

Intermittent inescapable footshock (IIFS) treatment, administered to 3-month-old male rats, resulted in analgesia as well as discrete immunological and endocrine changes. The splenic lymphocyte proliferative response to concanavalin A (ConA) and phytohemagglutinin (PHA) was decreased by 20% and 41%, respectively. The primary IgM plaque forming cell (PFC) response to sheep red blood cells (SRBC), however, was not altered by IIFS administered either immediately or 24 h after injection of SRBC. IIFS also produced a significant (20-fold) increase in plasma corticosterone (CORT) as compared to non-shocked controls. The shock-induced suppression of splenic lymphocyte mitogenic response to PHA was blocked by 10 mg/kg naltrexone (NTX) administered immediately before IIFS. NTX alone had no effect on this mitogen response. However, NTX significantly attenuated the shock-induced rise in CORT even though NTX alone significantly elevated CORT in the non-shocked controls. These data suggest that IIFS alters cellular immune response but not the primary IgM PFC response (a measure of humoral immune function) and that the immunomodulatory effects may involve both an opioid and a corticosteroid component with respect to alterations in the splenic lymphocyte mitogenic response to PHA.