F. Ango, L. Prézeau, T. Muller, J. C. Tu, B. Xiao et al., Agonist-independent activation of metabotropic glutamate receptors by the intracellular protein Homer, Nature, vol.15, issue.6840, pp.962-965, 2001.
DOI : 10.1038/35082096
URL : https://hal.archives-ouvertes.fr/inserm-00318959

J. L. Barker, J. H. Neale, T. G. Smith, and R. L. Macdonald, Opiate peptide modulation of amino acid responses suggests novel form of neuronal communication, Science, vol.199, issue.4336, pp.1451-1453, 1978.
DOI : 10.1126/science.204016

V. Beaumont, M. B. Hepworth, J. S. Luty, E. Kelly, and G. Henderson, Somatostatin Receptor Desensitization in NG108-15 Cells. A CONSEQUENCE OF RECEPTOR SEQUESTRATION, Journal of Biological Chemistry, vol.273, issue.50, pp.33174-33183, 1998.
DOI : 10.1074/jbc.273.50.33174

M. M. Behbehani, R. Y. Pun, E. D. Means, and D. K. Anderson, Thyrotropin-Releasing hormone has profound presynaptic action on cultured spinal cord neurons, Synapse, vol.335, issue.2, pp.169-174, 1990.
DOI : 10.1002/syn.890060208

M. J. Berridge, Neuronal Calcium Signaling, Neuron, vol.21, issue.1, pp.13-26, 1998.
DOI : 10.1016/S0896-6273(00)80510-3
URL : http://doi.org/10.1016/s0896-6273(00)80510-3

M. Bijak, Neuropeptide Y reduces epileptiform discharges and excitatory synaptic transmission in rat frontal cortex in vitro, Neuroscience, vol.96, issue.3, pp.487-494, 2000.
DOI : 10.1016/S0306-4522(99)00594-1

S. Boehm and H. Betz, Somatostatin inhibits excitatory transmission at rat hippocampal synapses via presynaptic receptors, Journal of Neuroscience, vol.17, pp.4066-4075, 1997.
DOI : 10.1111/j.1469-7793.1999.0439m.x
URL : http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2269514

H. Boudin, P. Sarret, J. Mazella, A. Schonbrunn, and A. Beaudet, Somatostatininduced regulation of SST2A receptor expression and cell surface availability in central neurons : role of receptor internalization, Journal of Neuroscience, vol.20, pp.5932-5939, 2000.

N. Burnashev, H. Monyer, P. H. Seeburg, and B. Sakmann, Divalent ion permeability of AMPA receptor channels is dominated by the edited form of a single subunit, Neuron, vol.8, issue.1, pp.189-198, 1992.
DOI : 10.1016/0896-6273(92)90120-3

K. Chergui, A. Bouron, E. Normand, and C. Mulle, Functional GluR6 kainate receptors in the striatum : indirect down regulation of synaptic transmission, Journal of Neuroscience, vol.20, pp.2175-2182, 2000.

S. L. Cole and M. Schindler, Characterisation of somatostatin sst2 receptor splice variants, Journal of Physiology-Paris, vol.94, issue.3-4, pp.217-237, 2000.
DOI : 10.1016/S0928-4257(00)00207-2

M. Connor, A. Yeo, and G. Henderson, receptor coupling to mobilization of intracellular calcium in SH-SY5Y human neuroblastoma cells, British Journal of Pharmacology, vol.74, issue.3, pp.455-463, 1997.
DOI : 10.1038/sj.bjp.0700920

A. M. Craig and H. Boudin, Molecular heterogeneity of central synapses : afferent and target regulation, Nature Neuroscience, vol.4, issue.6, pp.569-578, 2001.
DOI : 10.1038/88388

Z. Csaba and P. Dournaud, Cellular biology of somatostatin receptors, Neuropeptides, vol.35, issue.1, pp.1-23, 2001.
DOI : 10.1054/npep.2001.0848

Z. Csaba, A. Simon, L. Helboe, J. Epelbaum, and P. Dournaud, Neurochemical characterization of receptor-expressing cell populations by in vivo agonist-induced internalization: insights from the somatostatin sst2A receptor GABA : a dominant neurotransmitter in the hypothalamus, J. Comp. Neurol. in press Decavel C. & van den Pol A.N. Journal of Comparative Neurology, vol.302, pp.1019-1037, 1990.

S. L. Dickson, G. Leng, and I. C. Robinson, Systemic administration of growth hormone-releasing peptide activates hypothalamic arcuate neurons, Neuroscience, vol.53, issue.2, p.303306, 1993.
DOI : 10.1016/0306-4522(93)90197-N

P. Dournaud, A. Slama, A. Beaudet, and J. Epelbaum, Somatostatin receptors In: Handbook of Chemical Neuroanatomy Single synaptic events evoke NMDA receptor-mediated release of calcium from internal stores in hippocampal dendritic spines, Neuron, vol.16, issue.115, pp.1-43124, 1999.

O. Eyigor, A. Centers, and L. Jennes, Distribution of ionotropic glutamate receptor subunit mRNAs in the rat hypothalamus, The Journal of Comparative Neurology, vol.338, issue.1, pp.101-124, 2001.
DOI : 10.1002/cne.1167

C. Feleder, H. Jarry, S. Leonhardt, J. A. Moguilevsky, and W. Wuttke, Evidence to Suggest that Gonadotropin-Releasing Hormone Inhibits Its Own Secretion by Affecting Hypothalamic Amino Acid Neurotransmitter Release, Neuroendocrinology, vol.64, issue.4, pp.298-304, 1996.
DOI : 10.1159/000127132

X. B. Gao and A. N. Van-den-pol, Melanin concentrating hormone depresses synaptic activity of glutamate and GABA neurons from rat lateral hypothalamus, The Journal of Physiology, vol.432, issue.1, pp.237-252, 2001.
DOI : 10.1111/j.1469-7793.2001.0237b.x

R. Gardette, A. Faivre-bauman, C. Loudes, C. Kordon, and J. Epelbaum, Modulation by somatostatin of glutamate sensitivity during development of mouse hypothalamic neurons in vitro, Developmental Brain Research, vol.86, issue.1-2, pp.123-133, 1995.
DOI : 10.1016/0165-3806(95)00019-A

A. Ghetti and S. F. Heinemann, NMDA-dependent modulation of hippocampal kainate receptors by calcineurin and Ca 2+ /calmodulin-dependent protein kinase, Journal of Neuroscience, vol.20, pp.2766-2773, 2000.

A. Golard, L. W. Role, and S. A. Siegelbaum, Protein kinase C blocks somatostatininduced modulation of calcium current in chick sympathetic neurons, J. Neurophysiol, vol.70, pp.1639-1643, 1993.

P. Greengard, The Neurobiology of Slow Synaptic Transmission, Science, vol.294, issue.5544, pp.1024-1030, 2001.
DOI : 10.1126/science.294.5544.1024

O. P. Hamill, A. Marty, E. Neher, B. Sakmann, and F. J. Sigworth, Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches, Pfl??gers Archiv - European Journal of Physiology, vol.12, issue.2, pp.85-100, 1981.
DOI : 10.1007/BF00656997

G. E. Hardingham, F. J. Arnold, and H. Bading, A calcium microdomain near NMDA receptors : on switch for ERK-dependent synapse-to-nucleus communication, Nature Neuroscience, vol.4, issue.6, pp.565-566, 2001.
DOI : 10.1038/88380

L. Helboe, A. Hay-schmidt, C. E. Stidsen, and M. Moller, Immunohistochemical localization of the somatostatin receptor subtype 2 (sst2) in the central nervous system of the golden hamster (Mesocricetus auratus), The Journal of Comparative Neurology, vol.405, issue.2, pp.247-261, 1999.
DOI : 10.1002/(SICI)1096-9861(19990308)405:2<247::AID-CNE8>3.3.CO;2-M

L. Helboe, M. Moller, L. Norregaard, M. Schiodt, and C. E. Stidsen, Development of selective antibodies against the human somatostatin receptor subtypes sst1???sst5, Molecular Brain Research, vol.49, issue.1-2, pp.82-88, 1997.
DOI : 10.1016/S0169-328X(97)00127-7

T. Hökfelt, Neuropeptides in perspective: The last ten years, Neuron, vol.7, issue.6, pp.867-879, 1991.
DOI : 10.1016/0896-6273(91)90333-U

D. Hoyer, G. I. Bell, M. Berelowitz, J. Epelbaum, W. Feniuk et al., Classification and nomenclature of somatostatin receptors, Trends in Pharmacological Sciences, vol.16, issue.3, pp.86-88, 1995.
DOI : 10.1016/S0165-6147(00)88988-9

Y. H. Jo, M. E. Stoeckel, M. J. Freund-mercier, and R. Schlichter, Oxytocin modulates glutamatergic synaptic transmission between cultured neonatal spinal cord dorsal horn neurons, Journal of Neuroscience, vol.18, pp.2377-2386, 1998.

P. Jonas, C. Racca, B. Sakmann, P. H. Seeburg, and H. Monyer, Differences in Ca2+ permeability of AMPA-type glutamate receptor channels in neocortical neurons caused by differential GluR-B subunit expression, Neuron, vol.12, issue.6, pp.1281-1289, 1994.
DOI : 10.1016/0896-6273(94)90444-8

F. Kawai and P. Sterling, AMPA receptor activates a G-protein that suppresses a cGMP-gated current, Journal of Neuroscience, vol.19, pp.2954-2959, 1999.

G. A. Kinney, P. J. Emmerson, and R. J. Miller, Galanin-receptor mediated inhibition of glutamate release in the arcuate nucleus of the hypothalamus, Journal of Neuroscience, vol.18, pp.3489-3500, 1998.

S. B. Kombian, D. Mouginot, M. Hirasawa, and Q. J. Pittman, Vasopressin Preferentially Depresses Excitatory Over Inhibitory Synaptic Transmission in the Rat Supraoptic Nucleus In Vitro, Journal of Neuroendocrinology, vol.139, issue.4, pp.361-367, 2000.
DOI : 10.1046/j.1365-2826.2000.00462.x

C. Lanneau, C. Viollet, A. Faivre-bauman, C. Loudes, C. Kordon et al., Somatostatin receptor subtypes sst1 and sst2 elicit opposite effects on the response to glutamate of mouse hypothalamic neurones: an electrophysiological and single cell RT-PCR study, European Journal of Neuroscience, vol.89, issue.1, pp.204-212, 1998.
DOI : 10.1016/0306-4522(95)96912-W

C. Lanneau, M. T. Bluet-pajeot, P. Zizzari, Z. Csaba, P. Dournaud et al., Involvement of the Sst1 Somatostatin Receptor Subtype in the Intrahypothalamic Neuronal Network Regulating Growth Hormone Secretion: An in Vitro and in Vivo Antisense Study, Endocrinology, vol.141, issue.3, pp.967-979, 2000.
DOI : 10.1210/en.141.3.967

C. Lanneau, S. Peineau, F. Petit, J. Epelbaum, and R. Gardette, Somatostatin modulation of excitatory synaptic transmission between periventricular and arcuate hypothalamic nuclei in vitro, Journal of Neurophysiology, vol.84, pp.1464-1474, 2000.
URL : https://hal.archives-ouvertes.fr/inserm-00765174

H. K. Lee, K. Kameyama, R. L. Huganir, and M. K. Bear, NMDA Induces Long-Term Synaptic Depression and Dephosphorylation of the GluR1 Subunit of AMPA Receptors in Hippocampus, Neuron, vol.21, issue.5, pp.1151-1162, 1998.
DOI : 10.1016/S0896-6273(00)80632-7

F. Liu, Q. Wan, Z. B. Pristupa, X. M. Yu, Y. T. Wang et al., Direct protein-protein coupling enables cross-talk between dopamine D5 and ?-aminobutyric acid A receptors, Nature, vol.403, pp.274-280, 2000.

S. Q. Liu and S. G. Cull-candy, Synaptic activity at calcium-permeable AMPA receptors induces a switch in receptor subtype, Nature, vol.405, pp.454-457, 2000.

A. Manfridi, G. L. Forloni, A. Vezzani, F. Froditto, and M. G. De-simoni, Functional and histological consequences of quinolinic and kainic acid-induced seizures on hippocampal somatostatin neurons, Neuroscience, vol.41, issue.1, pp.127-135, 1991.
DOI : 10.1016/0306-4522(91)90203-Z

C. G. Wasterlain, Modulation of hippocampal excitability and seizures by galanin, Journal of Neuroscience, vol.20, pp.6276-6281, 2000.

A. R. Mcquiston and W. F. Colmers, Neuropeptide Y2 receptors inhibit the frequency of spontaneous but not miniature EPSCs in CA3 pyramidal cells of rat hippocampus, Journal of Neurophysiology, vol.76, pp.3159-3168, 1996.

@. Mothet, J. P. Parent, A. T. Wolosker, H. Brady, R. O. Jr et al., D-Serine is an endogenous ligand for the glycine site of the N-methyl-D-aspartate receptor, Proceedings of the National Academy of Sciences of the USA 97, pp.1133-1148, 2000.
DOI : 10.1073/pnas.97.9.4926

O. P. Ottersen and A. S. Landsend, Organization of Glutamate Receptors at the Synapse, European Journal of Neuroscience, vol.273, issue.11, 1997.
DOI : 10.1111/j.1460-9568.1997.tb01640.x

Y. C. Patel, Somatostatin and Its Receptor Family, Frontiers in Neuroendocrinology, vol.20, issue.3, pp.157-198, 1999.
DOI : 10.1006/frne.1999.0183

P. Sarret, J. M. Botto, J. P. Vincent, J. Mazella, and A. Beaudet, Preferential Expression of sst2A over sst2B Somatostatin Receptor Splice Variant in Rat Brain and Pituitary, Neuroendocrinology, vol.68, issue.1, p.43, 1998.
DOI : 10.1159/000054348

M. Schindler, P. P. Humphrey, and P. C. Emson, Somatostatin receptors in the central nervous system, Progress in Neurobiology, vol.50, issue.1, pp.9-47, 1996.
DOI : 10.1016/0301-0082(96)00030-5

S. Schulz, M. Häendel, M. Schreff, H. Schmidt, and V. Höllt, Localization of five somatostatin receptors in the rat central nervous system using subtype-specific antibodies, Journal of Physiology-Paris, vol.94, issue.3-4, pp.259-264, 2000.
DOI : 10.1016/S0928-4257(00)00212-6

D. L. Sodickson and B. P. Bean, Neurotransmitter activation of inwardly rectifying potassium current in dissociated hippocampal CA3 neurons : interactions among multiple receptors, Journal of Neuroscience, vol.18, pp.8153-8162, 1998.

D. Swandulla, H. U. Zeilhofer, U. Misgeld, and S. Beckh, Functional and Molecular Characteristics of the Glutamate Receptor Involved in Synaptic Transmission in the Hypothalamus, Annals of the New York Academy of Sciences, vol.455, issue.1 Molecular and, pp.163-173, 1994.
DOI : 10.1016/0896-6273(93)90203-4

S. H. Swope, S. J. Moss, C. D. Blackstone, and R. L. Huganir, Phosphorylation of ligand-gated ion channels : a possible mode of synaptic plasticity, FASEB Journal, vol.6, pp.2514-2523, 1992.

M. K. Tallent and G. R. Siggins, Somatostatin depresses excitatory but not inhibitory neurotransmission in rat CA1 hippocampus, Journal of Neurophysiology, vol.78, pp.3008-2018, 1997.

A. N. Van-den-pol, K. Obrietan, G. Chen, and A. B. Belousov, Kainate, and NMDA receptor RNA with in situ hybridization Neuropeptide Ymediated long-term depression of excitatory activity in suprachiasmatic nucleus neurons Presynaptic and postsynaptic actions and modulation of neuroendocrine neurons by a new hypothalamic peptide, hypocretin/orexin, Ionotropic glutamate-receptor gene expression in hypothalamus : localization of AMPA, pp.428-444, 1996.

A. Vezzani, A. Monno, M. Rizzi, A. Galli, and M. Barrios, Somatostatin release is enhanced in the hippocampus of partially and fully kindled rats, Neuroscience, vol.51, issue.1, pp.41-46, 1992.
DOI : 10.1016/0306-4522(92)90468-H

A. Vezzani and D. Hoyer, Brain somatostatin: a candidate inhibitory role in seizures and epileptogenesis, European Journal of Neuroscience, vol.70, issue.11, pp.3767-3776, 1999.
DOI : 10.1046/j.1460-9568.1999.00838.x

M. Vignes and G. L. Collingridge, The synaptic activation of kainate receptors, Nature, vol.388, pp.179-182, 1997.
URL : https://hal.archives-ouvertes.fr/hal-00659452

J. P. Wuarin and F. E. Dudek, Patch-clamp analysis of spontaneous synaptic currents in supraoptic neuroendocrine cells of the rat hypothalamus, Journal of Neuroscience, vol.13, pp.2323-2331, 1993.

S. N. Yang, Sustained enhancement of AMPA receptor- and NMDA receptor-mediated currents induced by dopamine d1/d5 receptor activation in the hippocampus: An essential role of postsynaptic Ca2+, Hippocampus, vol.260, issue.1, pp.57-63, 2000.
DOI : 10.1002/(SICI)1098-1063(2000)10:1<57::AID-HIPO6>3.0.CO;2-0

R. Yuste and W. Denk, Dendritic spines as basic functional units of neuronal integration, Nature, vol.375, issue.6533, pp.682-684, 1995.
DOI : 10.1038/375682a0

Y. Zhu and J. L. Yakel, Calcineurin modulates G-protein-mediated inhibition of N-type calcium channels in rat sympathetic neurons, Journal of Neurophysiology, vol.78, p.11611169, 1997.

H. Zitzer, H. H. Hönck, D. Bächner, D. Richter, and H. J. Kreienkamp, Somatostatin Receptor Interacting Protein Defines a Novel Family of Multidomain Proteins Present in Human and Rodent Brain, Journal of Biological Chemistry, vol.274, issue.46, pp.32997-33001, 1999.
DOI : 10.1074/jbc.274.46.32997

. Acknowlegdements, We thank Dr Faivre-Bauman and Dr Loudes for the microdissection technique

. Recordings, NMDA currents in one neurone before (CTRL) and during octreotide application (OCT) in the absence of external calcium Each trace was fitted by a spline curve with a uniform local average smoother of span 100 Scale bars : 20 pA, 1 s Figure 6 : Role of group I mGluRs in sst2-evoked AMPA depression in mediobasal hypothalamic cultures. (All experiments were performed in the absence of extracellular calcium) (A) Time plot of normalized responses to coapplication of AMPA and trans-(+)-ACPD