Effect of NDP-a-MSH on PPAR-c and –b Expression and Anti-Inflammatory Cytokine Release in Rat Astrocytes and Microglia

Brain inflammation plays a central role in numerous brain pathologies. Microglia and astrocytes are the main effector cells that become activated when an inflammatory process takes place within the central nervous system. a-melanocytestimulating hormone (a-MSH) is a neuropeptide with proven anti-inflammatory properties. It binds with highest affinity to the melanocortin receptor 4 (MC4R), which is present in astrocytes and upon activation triggers anti-inflammatory pathways. The aim of this research was to identify anti-inflammatory mediators that may participate in the immunomodulatory effects of melanocortins in glial cells. Since peroxisome proliferator-activated receptors (PPARs) have recently been implicated in the modulation of inflammation, we investigated the effect of an a-MSH analog, [Nle4 , D-Phe7]- a-MSH (NDP-a-MSH), on PPAR-b and PPAR-c gene and protein expression in rat primary astrocytes and microglia. We initially demonstrated that rat primary microglia express MC4R and showed that treatment with NDP-a-MSH increases PPAR-c protein levels and strongly decreases PPAR-b levels in both astrocytes and microglia. We also showed that extracellular signal-regulated kinase 1/2 (ERK1/2)–mediated signaling is partially involved in these effects in a cell-specific fashion. Finally, we showed that NDP-a-MSH stimulates the release of the anti-inflammatory cytokines IL-10 and TGF-b from microglia and astrocytes, respectively. The presented data suggest a role for IL-10 and TGF-b in the protective action of melanocortins and a connection between MC4R pathway and that of the nuclear receptor PPAR-c. This is the first report providing evidence that MC4R is expressed in rat primary microglia and that melanocortins modulate PPAR levels in glial cells. Our findings provide new insights into the mechanisms underlying the activation of glial MC4R and open perspectives for new therapeutic strategies for the treatment of inflammation-mediated brain diseases.Fil: Carniglia, Lila. INSTITUTO DE INVESTIGACIONES BIOMEDICAS;Fil: Durand, Daniela Elizabeth. INSTITUTO DE INVESTIGACIONES BIOMEDICAS;Fil: Caruso, Carla Mariana. INSTITUTO DE INVESTIGACIONES BIOMEDICAS;Fil: Lasaga, Mercedes Isabel. INSTITUTO DE INVESTIGACIONES BIOMEDICAS

Stress, alcohol and infection during early development: a brief review of common outcomes and mechanisms.

Although stress is an adaptive physiological response to deal with adverse conditions, its occurrence during the early stages of life, such as infancy or adolescence, can induce adaptations in multiple physiological systems, including the reproductive axis, the hypothalamic‐pituitary‐adrenal (HPA) axis, the limbic cortex and the immune system. These early changes have consequences in adult life, as seen in the physiological and behavioural responses to stress. This review highlights the impact of several stress challenges incurred at various stages of development (perinatal, juvenile, adolescent periods) and how the developmental timing of early‐life stress confers unique physiological adaptations that may persist across the lifespan. In doing so, we emphasise how intrinsic sex differences in the stress response might contribute to sex‐specific vulnerabilities, the molecular processes underlying stress in the adult, and potential therapeutic interventions to mitigate the effects of early stage stress, including the novel molecular mechanism of SUMOylation as a possible key target of HPA regulation during early‐life stress.Fil: Surkin, Pablo Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Breanhouse H. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Deak T. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Liberman AC. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigación en Biomedicina de Buenos Aires - Instituto Partner de la Sociedad Max Planck; ArgentinaFil: Lasaga, Mercedes Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; Argentin

Astrocytes: New Targets of Melanocortin 4 Receptor Actions

Astrocytes exert a wide variety of functions with paramount importance in brain physiology. After injury or infection, astrocytes become reactive and they respond by producing a variety of inflammatory mediators that help maintain brain homeostasis. Loss of astrocyte functions as well as their excessive activation can contribute to disease processes; thus, it is important to modulate reactive astrocyte response. Melanocortins are peptides with well-recognized anti-inflammatory and neuroprotective activity. Although melanocortin efficacy was shown in systemic models of inflammatory disease, mechanisms involved in their effects have not yet been fully elucidated. Central anti-inflammatory effects of melanocortins and their mechanisms are even less well known, and, in particular, the effects of melanocortins in glial cells are poorly understood. Of the five known melanocortin receptors (MCRs), only subtype 4 is present in astrocytes. MC4R has been shown to mediate melanocortin effects on energy homeostasis, reproduction, inflammation, and neuroprotection and, recently, to modulate astrocyte functions. In this review, we will describe MC4R involvement in anti-inflammatory, anorexigenic, and anti-apoptotic effects of melanocortins in the brain. We will highlight MC4R action in astrocytes and discuss their possible mechanisms of action. Melanocortin effects on astrocytes provide a new means of treating inflammation, obesity, and neurodegeneration, making them attractive targets for therapeutic interventions in the CNS.Fil: Caruso, Carla Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Carniglia, Lila. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Biología Celular e Histología. Centro de Investigación en Reproducción; ArgentinaFil: Durand, Daniela Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Scimonelli, Teresa Nieves. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico - CONICET - Córdoba. Instituto de Farmacología Experimental de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; ArgentinaFil: Lasaga, Mercedes Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas; Argentin

NDP-MSH reduces oxidative damage induced by palmitic acid in primary astrocytes

Recent findings relate obesity to inflammation in key hypothalamic areas for body weight control. Hypothalamic inflammation has also been related to oxidative stress. Palmitic acid (PA) is the most abundant free fatty acid found in food, and in vitro studies indicate that it triggers a pro-inflammatory response in the brain. Melanocortins are neuropeptides with proven anti-inflammatory and neuroprotective action mediated by melanocortin receptor 4 (MC4R), but little is known about the effect of melanocortins on oxidative stress. The aim of this study was to investigate whether melanocortins could alleviate oxidative stress induced by a high fat diet (HFD) model. We found that NDP-MSH treatment decreased PA-induced reactive oxygen species production in astrocytes, an effect blocked by the MC4R inhibitor JKC363. NDP-MSH abolished nuclear translocation of Nrf2 induced by PA and blocked the inhibitory effect of PA on superoxide dismutase (SOD) activity and glutathione levels while it also per se increased activity of SOD and γ-glutamate cysteine ligase (γ-GCL) antioxidant enzymes. However, HFD reduced hypothalamic MC4R and brain derived neurotrophic factor mRNA levels, thereby preventing the neuroprotective mechanism induced by melanocortins.Fil: Ramírez, Delia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Saba, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Turati, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Carniglia, Lila. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Imsen, Mercedes. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Mohn, Claudia Ester. Universidad de Buenos Aires. Facultad de Odontología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; ArgentinaFil: Scimonelli, Teresa Nieves. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Farmacología Experimental de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Farmacología Experimental de Córdoba; ArgentinaFil: Durand, Daniela Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Caruso, Carla Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Lasaga, Mercedes Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; Argentin

Astrocytes from cortex and striatum show differential responses to mitochondrial toxin and BDNF: Implications for protection of striatal neurons expressing mutant huntingtin

Background: Evidence shows significant heterogeneity in astrocyte gene expression and function. We previously demonstrated that brain-derived neurotrophic factor (BDNF) exerts protective effects on whole brain primary cultured rat astrocytes treated with 3-nitropropionic acid (3NP), a mitochondrial toxin widely used as an in vitro model of Huntington’s disease (HD). Therefore, we now investigated 3NP and BDNF effects on astrocytes from two areas involved in HD: the striatum and the entire cortex, and their involvement in neuron survival. Methods: We prepared primary cultured rat cortical or striatal astrocytes and treated them with BDNF and/or 3NP for 24 h. In these cells, we assessed expression of astrocyte markers, BDNF receptor, and glutamate transporters, and cytokine release. We prepared astrocyte-conditioned medium (ACM) from cortical and striatal astrocytes and tested its effect on a cellular model of HD. Results: BDNF protected astrocytes from 3NP-induced death, increased expression of its own receptor, and activation of ERK in both cortical and striatal astrocytes. However, BDNF modulated glutamate transporter expression differently by increasing GLT1 and GLAST expression in cortical astrocytes but only GLT1 expression in striatal astrocytes. Striatal astrocytes released higher amounts of tumor necrosis factor-α than cortical astrocytes in response to 3NP but BDNF decreased this effect in both populations. 3NP decreased transforming growth factor-β release only in cortical astrocytes, whereas BDNF treatment increased its release only in striatal astrocytes. Finally, we evaluated ACM effect on a cellular model of HD: the rat striatal neuron cell line ST14A expressing mutant human huntingtin (Q120) or in ST14A cells expressing normal human huntingtin (Q15). Neither striatal nor cortical ACM modified the viability of Q15 cells. Only ACM from striatal astrocytes treated with BDNF and ACM from 3NP + BDNF-treated striatal astrocytes protected Q120 cells, whereas ACM from cortical astrocytes did not.Conclusions: Data suggest that cortical and striatal astrocytes respond differently to mitochondrial toxin 3NP and BDNF. Moreover, striatal astrocytes secrete soluble neuroprotective factors in response to BDNF that selectively protect neurons expressing mutant huntingtin implicating that BDNF modulation of striatal astrocyte function has therapeutic potential against neurodegeneration.Fil: Saba, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: López Couselo, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Turati, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Carniglia, Lila. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Durand, Daniela Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: de Laurentiis, Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Centro de Estudios Farmacológicos y Botánicos. Universidad de Buenos Aires. Facultad de Medicina. Centro de Estudios Farmacológicos y Botánicos; ArgentinaFil: Lasaga, Mercedes Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Caruso, Carla Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; Argentin

Unraveling the β-AMYLOID clearance by astrocytes: Involvement of metabotropic glutamate receptor 3, sAPPα, and class-A scavenger receptor

The mechanics of β-amyloid (Aβ) clearance by astrocytes has not been univocally described, with different mediators appearing to contribute to this process under different conditions. Our laboratory has demonstrated neuroprotective effects of astroglial subtype 3 metabotropic glutamate receptor (mGlu3R), which are dependent on the secreted form of the amyloid precursor protein (sAPPα) as well as on Aβ clearance; however, the mechanism underlying mGlu3R-induced Aβ uptake by astrocytes remains unclear. The present study shows that conditioned medium from mGlu3R-stimulated astrocytes increased Aβ uptake by naïve astrocytes through a mechanism dependent on sAPPα, since sAPPα depletion from conditioned medium inhibited Aβ phagocytosis. Concordantly, recombinant sAPPα also increased Aβ uptake. Since we show that both sAPPα and the mGlu3R agonist LY379268 increased expression of class-A scavenger receptor (SR-A) in astrocytes, we next determined whether SR-A mediates mGlu3R- or sAPPα-induced Aβ uptake by using astrocyte cultures derived from SR-A knockout mice. We found that the effects of LY379268 as well as sAPPα on Aβ uptake were abolished in SR-A-deficient astrocytes, indicating a major role for this scavenger receptor in LY379268- and sAPPα-stimulated Aβ clearance by astrocytes. We also show results of coimmunoprecipitation and functional assays offering evidence of possible heterotrimerization of sAPPα with Aβ and SR-A which could allow Aβ to enter the astrocyte. In conclusion the present paper describes a novel pathway for Aβ clearance by astrocytes involving sAPPα as an enhancer of SR-A-dependent Aβ phagocytosis.Fil: Durand, Daniela Elizabeth. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Turati, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Rudi, María Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Ramírez, Delia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Saba, Julieta. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Caruso, Carla Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Carniglia, Lila. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: von Bernhardi, Rommy. Pontificia Universidad Católica de Chile; ChileFil: Lasaga, Mercedes Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; Argentin

Tachykinins and the hypothalamo–pituitary–gonadal axis: an update

Tachykinins play a critical role in neuroendocrine regulation of reproduction. The best known members of the family are substance P (SP), neurokinin A and neurokinin B. Tachykinins mediate their biological actions through three G protein-coupled receptors, named NK1, NK2, and NK3. SP was suggested to play an important role in the ovulatory process in mammals and humans. Recent findings suggest a role of tachykinins in the aging of the hypothalamo–pituitary–gonadal axis. A high presence of SP was found in the sheep pars tuberalis and evidence indicates that it may have some role in the control of prolactin secretion. The presence of SP was confirmed in Leydig cells of the rat testes of animals submitted to constant light or treated with estrogens. Tachykinins were found to increase the motility of human spermatozoa. Tachykinins were also found to be present in the mouse ovary and more specifically, in the granulose cells. It is possible that tachykinins may play an important role in the ovarian function. NKB has been implicated in the steroid feedback control of GnRH release. Human mutations in the gene encoding this peptide or its receptor (TACR3) lead to a defect in the control of GnRH. A specific subset of neurons in the arcuate nucleus of the hypothalamus, colocalized three neuropeptides, kisspeptin, NKB and dynorphin. This subpopulation of neurons mediates the gonadal hormone feedback control of GnRH secretion. NKB/NK3 signaling plays a role in puberty onset and fertility in humans. This minireview summarizes the recent data about the action of tachykinins on the hypothalamo–pituitary–gonadal axis.Fil: Lasaga, Mercedes Isabel. Universidad de Buenos Aires. Facultad de Medicina; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Debeljuk, Luciano. Southern Illinois University; Estados Unido

Dopamine partial agonist actions of the glutamate receptor agonists LY 354,740 and LY 379,268

Because glutamate compounds alter the release of dopamine and prolactin, the present study examined whether group II metabotropic receptor agonists, LY 354,740 and LY 379,268, had any direct in vitro action on dopamine D2 receptors on rat striatal tissue, cloned D2Long receptors, and prolactin release from anterior pituitary cells. In competition versus the D2-specific ligand [(3)H]domperidone, LY 354,740 had a dissociation constant of 24 nM at D2(High) (the functional high-affinity state of dopamine D2 receptors), while the value for LY 379,268 was 21 nM. LY 354,740 also stimulated by 50% the incorporation of [(35)S]-GTP-gamma-S at a concentration of 120 nM, but its maximal stimulation was only 22% of the maximum elicited by dopamine. LY 379,268 stimulated by 50% the incorporation of [(35)S]-GTP-gamma-S at 280 nM, but its maximal stimulation was also only 22% of the maximum elicited by dopamine. However, both LY 354,740 and LY 379,268 potently inhibited the dopamine-induced incorporation of [(35)S]-GTP-gamma-S with inhibitory Ki values of 43 nM and 30 nM, respectively. The release of prolactin from rat isolated anterior pituitary cells in culture was 50% inhibited by 20 nM LY 379,268 and by 100 nM LY 354,740. These Ki values are similar to those known for the mGluR II receptor, suggesting that these compounds may have both glutamate and dopamine actions in vivo. The dopamine agonist and antagonist actions of these compounds indicate that these drugs have properties of a dopamine partial agonist, and may, therefore, have antipsychotic action.Fil: Seeman, Philip. University of Toronto; CanadáFil: Caruso, Carla Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Lasaga, Mercedes Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; Argentin

Memantine agonist action at dopamine D2High receptors

Memantine is reported to improve symptoms in moderate cases of Alzheimer´s disease and Parkinson´s disease, but is also known to trigger psychosis in some Parkinson patients. Because these clinical features suggested a possible dopamine component of memantine action, we measured the potency of memantine on the functional high-affinity state of dopamine D2 receptors, or D2(High). Using [(3)H]domperidone to label D2 receptors, the memantine dissociation constant at D2(High) was 917 +/- 23 nM for rat striatal D2 receptors and 137 +/- 19 nM for human cloned D2Long receptors. The memantine dissociation constant for striatal N-methyl-D-aspartate (NMDA) receptors labeled by [(3)H]MK 801 was 2200 +/- 400 nM. Memantine stimulated the incorporation of [(35)S]GTP-gamma-S into D2-expressing Chinese Hamster Ovary cells with a dissociation constant of 1200 +/- 400 nM. Memantine, between 200 and 2000 nM, directly acted on D2(High) to inhibit the release of prolactin from isolated anterior pituitary cells in culture. Because the memantine potencies at NMDA receptors and dopamine D2(High) receptors are of a similar order of magnitude, it is likely that the clinical features of memantine can be attributed to its action at both types of receptors.Fil: Seeman, Philip. University of Toronto; CanadáFil: Caruso, Carla Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; ArgentinaFil: Lasaga, Mercedes Isabel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas; Argentin

Effect of ionotropic and metabotropic glutamate agonists and D-aspartate on prolactin release from anterior pituitary cells

Although the presence of ionotropic (iGluRs) and metabotropic (mGluRs) glutamate receptors has been demonstrated in the anterior pituitary, recent reports on the direct effect of glutamate on prolactin (PRL) secretion by anterior pituitary cells have presented contradictory results. Hence, the aim of this study was to determine the effect of ionotropic (iGluRs) and metabotropic (mGluRs) glutamate receptor agonists on prolactin (PRL) release. In addition, since D-Aspartate (D-Asp) is found in the pituitary and is involved in neuroendocrine regulation, we also studied the direct action of D-Asp on PRL secretion. Finally, since the posterior pituitary participates in the regulation of PRL secretion, we examined the influence of the posterior pituitary on the effects of NMDA and D-Asp on PRL release. - Glutamate (1000 μM) increased PRL secretion from cultured anterior pituitary cells. Both NMDA (100 μM) and kainate (100 μM) increased PRL secretion and these effects were blocked by a specific NMDA receptor antagonist. AMPA did not modify PRL release in these cultures. The group I and II mGluR agonist, trans-ACPD (1000 μM), and a specific group II mGluR agonist, L-CCG-I (100-1000 μM), inhibited whereas specific group I and III mGluR agonists, 3-HPG and L-AP4 respectively, had no effect on PRL release. Finally, D-Asp (100-1000 μM) stimulated PRL secretion and this effect was reduced by a NMDA receptor antagonist. When anterior pituitary cells were cultured in the presence of posterior pituitary cells, NMDA did not modify PRL or GABA release, while D-Asp increased PRL secretion and decreased GABA release in these cocultures. - In conclusion, our results show that L-glutamate has a differential direct effect on PRL release: it exerts a stimulatory action via iGluRs and an inhibitory effect via mGluRs. D-Asp could directly stimulate PRL release through NMDA receptors. D-Asp may also stimulate PRL release by decreasing GABA release from the posterior pituitary.Fil: Pampillo, M.. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Biología Celular e Histología. Centro de Investigación en Reproducción; ArgentinaFil: Theas, Maria Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Biología Celular e Histología. Centro de Investigación en Reproducción; ArgentinaFil: Duvilanski, Beatriz Haydee. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Biología Celular e Histología. Centro de Investigación en Reproducción; ArgentinaFil: Seilicovich, Adriana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentina. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Biología Celular e Histología. Centro de Investigación en Reproducción; ArgentinaFil: Lasaga, Mercedes Isabel. Universidad de Buenos Aires. Facultad de Medicina. Departamento de Biología Celular e Histología. Centro de Investigación en Reproducción; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay; Argentin