神經細胞與肌細胞形成突觸的過程非常複雜，這過程中除了細胞彼此間藉著細胞黏著因子的直接接觸產生交互作用之外，許多訊號分子如ATP、NO、HPETE的出現及一些神經滋養因子的產生會進一步穩定整個突觸結構。在本論文中我們將探討Insulin-like growth factor-I (IGF-I) 在胚胎時期對神經細胞與肌細胞突觸形成過程所扮演的角色。
IGFs是在1970年代被cloned出來，隨著眾多實驗的進行發現IGFs除了在生理代謝上有著類似胰島素的功能，在週圍及中樞神經系統也扮演著生長、分化及再生的重要角色，由於目前對於IGF-I在胚胎早期神經細胞與肌細胞間突觸形成過程中所扮演的角色所之甚少，因此本實驗利用非洲爪蟾的神經細胞與肌細胞的混合培養( Xenopus nerve-muscle co-culture )，以whole-cell patch clamp的電生理記錄的方式來探討IGF-I在胚胎發育早期突觸形成過程中所扮演的角色以及這中間可能的訊息傳遞路徑。藉由在肌細胞記錄神經所釋放的ACh之後，ACh打開肌細胞上ACh receptor而造成自發性電流，我們可以清楚的觀察到神經細胞的活性，當我們在培養皿中加入IGF-I之後約經15分鐘後我們發現自發性神經傳導物質釋放的頻率有顯著的增加。由於神經細胞釋放神經傳導物質和神經末梢內鈣離子的濃度有很大的關係，因此我們設計一系列實驗來釐清鈣離子的來源。實驗結果顯示在Ca2+ free Ringer以及鈣離子通道阻斷劑Cd2+的存在下IGF-I對神經活性的促進作用依然存在，顯示IGF-I對神經活性的促進作用所需的鈣離子來源不是來自細胞外，而是由細胞內的鈣離子儲存池所提供。此外，為了更進一步證實IGF-I的作用和鈣離子儲存池的關係，我們利用鈣離子儲存池上的鈣離子通道阻斷劑：IP3 receptor inhibitor (XeC, 2-APB) 及ryanodine receptor inhibitor (TMB-8) 或是用鈣離子儲存池的排空劑thapsigargin以阻斷細胞內鈣離子的來源，實驗結果一致顯示在沒有細胞內的鈣離子來源的情況下IGF-I便無法再促進神經活性。至於IGF-I的那些訊息傳遞路徑和促進神經活性有關？目前已知IGF-I有三條訊息傳遞路徑─PI 3-kinase、PLCg和MAP kinase。這次的實驗結果發現，IGF-I的作用會因PI 3-kinase和PLCg的活性被抑制而消失，但對於MAP kinase的抑制作用沒有明顯的影響。
當神經末梢內鈣離子濃度升高時，Ca2+會透過和calmoldulin形成複合物而將Ca2+/calmoldulin-dependent protein kinase (CaMK II) 活化，使得原本藉著synapsin I而束縛在細胞骨架上的突觸小泡( synaptic vesicle )因synapsin I被CaMK II磷酸化而釋放出來，增加了突觸小泡被釋放的機率。實驗結果發現在CaMK II抑制劑的處理下，IGF-I的作用明顯被抑制，顯示IGF-I確實能提高細胞內Ca2+而活化CaMK II來增加神經傳導物質釋放的頻率。
綜合以上結果，我們認為IGF-I能夠藉由PI 3-kinase及PLCg路徑的活化而打開IP3及ryanodine sensitive的鈣離子儲存池，使神經末梢內鈣離子濃度升高後，鈣離子經由活化CaMK II pathway而增加神經傳遞物質的釋放。

Successful synaptic transmission at the neuromuscular junction depends on the precise alignment of the nerve terminals with the postsynaptic specialization of the muscle fiber. It is increasingly apparent that this precision is achieved during development and maintained in the adult through signals exchanged between motoneurons and their target muscle fibers that serve to coordinate their spatial and temporal differentiation. Several aspects of neuronal differentiation appear to be dependent on retrograde signals from the target and studies about synaptic modulation have now focused attention on the characterization of proteins that mediate retrograde signals regulating the organization and function of nerve terminals. According to the published evidences, we find Insulin-like growth factor-I (IGF-I ) might be one of these potential factors.
The acute application of IGF-I, a factor which has been addressed to widely express in developing myocyte, dose-dependently enhances the spontaneous acetylcholine secretion at developing neuromuscular synapses in Xenopus cell culture using whole-cell patch clamp recording. The IGF-I-induced potentiating effect is not abolished when calcium is eliminated from culture medium or bath application of pharmacological calcium channel blocker cadmium, indicating calcium influx through voltage-activated calcium channels are not required. We further define the roles of intracellular Ca2+ stores in IGF-I-induced synaptic potentiation. To approach this problem, Ca2+-ATPase inhibitor thapsigargin were initially used to deplete internal Ca2+ stores. IGF-I no longer elicited any changes in SSC frequency in thapsigargin-treated synapses suggesting that an increase in [Ca2+]i due to Ca2+ release from intracellular Ca2+ stores may contribute to the facilitation of transmitter release induced by IGF-I. Application of membrane-permeable inhibitors of IP3-induced Ca2+ release 2-aminoethoxydiphenyl borate (2-APB) or Xestospongin C (XeC) effectively occluded the increase of SSC frequency elicited by IGF-I. Furthermore, pretreatment of the cultures with ryanodine receptor antagonist 8-(dethylamino) octyl 3, 4, 5-trimethoxybenzoate (TMB-8) also blocked the IGF-I effects indicating that IGF-I activates IP3 and/or ryanodine pathway to initiate calcium release from intracellular stores which subsequently potentiate transmitter release. Treating cells with inhibitors of phosphoinositide-3 kinase (wortmannin and LY294002) and Phospholipase C-g (U73122), but not inhibitor of MAP kinase (PD98059) abolishes IGF-1-induced potentiation of synaptic transmission. Inhibition of Ca2+/calmodulin-dependent protein kinase II (CaMKII) by KN-62 effectively blocks the effect of IGF-I. Taken collectively, our results obtained suggest that IGF-I potentiates neurotransmitter secretion by stimulating Ca2+ release from IP3 and ryanodine sensitive intracellular calcium stores via activate PI3 and/or PLC-g signaling cascades, which leading to an activation of CaMKII-dependent transmitter release.

目 錄
　　　　　　　　　　　　 頁數
中文摘要…………………………………………………………………...1
英文摘要…………………………………………………………………...4
緒論………………………………………………………………………...6
Insulin-like growth factor system .................................................................7
IGF-1 and Type 1 IGF receptor ………………………………...............….8
Insulin-like growth factor binding proteins ( IGFBPs )………..................11
IGFs在神經系統的分佈及表現情形…………………………………….12
神經傳導物質的分泌………………………………………….................13
實驗目的……………………………………………………….................16
實驗材料……………………………………………………….................17
實驗方法……………………………………………………….................19
1.電生理記錄方法……………………………………………………....................19
2.實驗數據分析及統計………………………………………………....................20
3.實驗用試劑及供應者………………………………………………....................20
實驗結果………………………………………………………………….21
討論……………………………………………………………………….29
參考文獻………………………………………………………………….33


圖檔順序 頁數
附圖 1…………………………………………………………………….44
附圖 2…………………………………………………………………….46
附圖 3…………………………………………………………………….47
附圖 4…………………………………………………………………….48
附圖 5…………………………………………………………………….49
Fig. 1………………………………………………………………………50
Fig. 2………………………………………………………………………52
Table 1…………………………………………………………………….53
Fig. 3………………………………………………………………………54
Fig. 4………………………………………………………………………56
Fig. 5………………………………………………………………………58
Fig. 6………………………………………………………………………60
Fig. 7………………………………………………………………………61
Fig. 8 .……………………………………………………………………..63
Fig. 9………………………………………………………………………65

參考文獻
Adams, T.E., Epa, V.C., Garrett, T.P. and Ward, C.W. (2000) Structure and function of the type 1 insulin-like growth factor receptor. Cell Mol. Life Sci. 57, 1050-93.
Aguado, F., Fernandez, T., Martinez-Murillo, R., Rodrigo, J., Cacicedo, L. and Sanchez-Franco, F. (1992) Immunocytochemical localization of insulin-like growth factor I in the hypothalamo-hypophyseal system of the adult rat. Neuroendocrinology 56, 856-63.

Aizenman, Y., and de Vellis, J. (1987) Brain neurons develop in a serum and glial free environment: effects of transferrin, insulin, insulin-like growth factor-I and thyroid hormone on neuronal survival, growth and differentiation. Brain Res. 406, 32-42.

Almers, W. (1990) Exocytosis. Annu. Rev. Physiol. 52, 607-24.

Anderson, M.J., Cohen, M.W. and Zorychta, E. (1977) Effects of innervation on the distribution of acetylcholine receptors on cultured muscle cells. J. Physiol. 268, 731-56.

Andersson, I.K., Edwall, D., Norstedt, G., Rozell, B., Skottner, A. and Hansson, H.A. (1988) Differing expression of insulin-like growth factor I in the developing and in the adult rat cerebellum. Acta. Physiol. Scand. 132, 167-73.

Bartlett, W.P., Li, X.S., Williams, M. and Benkovic, S. (1991) Localization of insulin-like growth factor-1 mRNA in murine central nervous system during postnatal development. Dev. Biol. 147, 239-50.

Baxter, R.C. (1995) Insulin-like growth factor binding proteins as glucoregulators. Metabolism 44, 12-7.

Bence-Hanulec, K.K., Marshall, J. and Blair, L.A. (2000) Potentiation of neuronal L calcium channels by IGF-1 requires phosphorylation of the alpha1 subunit on a specific tyrosine residue. Neuron 27, 121-31.

Bencherif, M., Eisenhour, C.M., Prince, R.J., Lippiello, P.M. and Lukas, R.J. (1995) The "calcium antagonist" TMB-8 [3,4,5-trimethoxybenzoic acid 8-(diethylamino)octyl ester] is a potent, non-competitive, functional antagonist at diverse nicotinic acetylcholine receptor subtypes. J. Pharmacol. Exp. Ther. 275, 1418-26.

Berridge, M.J. (1998) Neuronal calcium signaling. Neuron 21, 13-26.

Bi, G. and Poo, M. (2001) Synaptic modification by correlated activity: Hebb's postulate revisited. Annu. Rev. Neurosci. 24, 139-66.

Blair, L.A., Bence-Hanulec, K.K., Mehta, S., Franke, T., Kaplan, D. and Marshall, J. (1999) Akt-dependent potentiation of L channels by insulin-like growth factor-1 is required for neuronal survival. J. Neurosci. 19, 1940-51.

Bondy, C.A., Werner, H., Roberts, C.T. J.r. and LeRoith, D. (1990) Cellular pattern of insulin-like growth factor-I (IGF-I) and type I IGF receptor gene expression in early organogenesis: comparison with IGF-II gene expression. Mol. Endocrinol. 4, 1386-98.

Bondy, C.A. (1991) Transient IGF-I gene expression during the maturation of functionally related central projection neurons. J. Neurosci. 11, 3442-55.

Bondy, C., Werner, H., Roberts, C.T., Jr. and LeRoith, D. (1992) Cellular pattern of type-I insulin-like growth factor receptor gene expression during maturation of the rat brain: comparison with insulin-like growth factors I and II. Neuroscience 46, 909-23.

Caroni, P. and Grandes, P. (1990) Nerve sprouting in innervated adult skeletal muscle induced by exposure to elevated levels of insulin-like growth factors. J. Cell Biol. 110, 1307-17.

Caroni, P. (1993) Activity-sensitive signaling by muscle-derived insulin-like growth factors in the developing and regenerating neuromuscular system. Ann. N. Y. Acad. Sci. 692, 209-22.

Caroni, P. and Schneider, C. (1994) Signaling by insulin-like growth factors in paralyzed skeletal muscle: rapid induction of IGF1 expression in muscle fibers and prevention of interstitial cell proliferation by IGF-BP5 and IGF-BP4. J. Neurosci. 14, 3378-88.

Caroni, P., Schneider, C., Kiefer, M.C. and Zapf, J. (1994) Role of muscle insulin-like growth factors in nerve sprouting: suppression of terminal sprouting in paralyzed muscle by IGF-binding protein 4. J. Cell Biol. 125, 893-902.


Cheatham, L., Monfar, M., Chou, M.M. and Blenis, J. (1995) Structural and functional analysis of pp70S6k. Proc. Natl. Acad. Sci. U. S. A. 92, 11696-700.

Daughaday, W.H., Hall, K., Raben, M.S., Salmon, W.D. Jr, van den Brande JL, van Wyk JJ. (1972) Somatomedin: proposed designation for sulphation factor. Nature 235, 107.

D'Costa, A.P., Prevette, D.M., Houenou, L.J., Wang, S., Zackenfels, K., Rohrer, H., Zapf, J., Caroni, P. and Oppenheim, R.W. (1998) Mechanisms of insulin-like growth factor regulation of programmed cell death of developing avian motoneurons. J. Neurobiol. 36, 379-94.

Elgin, R.G., Busby, W.H. J.r. and Clemmons, D.R. (1987) An insulin-like growth factor (IGF) binding protein enhances the biologic response to IGF-I. Proc. Natl. Acad. Sci. U. S. A. 84, 3254-8.

Evers, J., Laser, M., Sun, Y.A., Xie, Z.P. and Poo, M.M. (1989) Studies of nerve-muscle interactions in Xenopus cell culture: analysis of early synaptic currents. J. Neurosci. 9, 1523-39.

Florini, J.R., Ewton, D.Z. and Magri, K.A. (1991) Hormones, growth factors, and myogenic differentiation. Annu. Rev. Physiol. 53, 201-16.

Foncea, R., Andersson, M., Ketterman, A., Blakesley, V., Sapag-Hagar, M., Sugden, P.H., LeRoith, D. and Lavandero, S. (1997) Insulin-like growth factor-I rapidly activates multiple signal transduction pathways in cultured rat cardiac myocytes. J. Biol. Chem. 272, 19115-24.

Frost, R.A. and Tseng, L. (1991) Insulin-like growth factor-binding protein-1 is phosphorylated by cultured human endometrial stromal cells and multiple protein kinases in vitro. J. Biol. Chem. 266, 18082-8.

Froesch, E.R., H. Burgi, E.B. Ramseier, P. Bally, and A. Labhart. (1963) Antibody-suppressible and nonsuppressible insulin-like activates in human serum and their physiologic significance. An insulin assay with adipose tissue of increased precision and specificity. J. Clin. Invest. 42, 1816-34.

Fu, W.M. and Poo, M.M. (1991) ATP potentiates spontaneous transmitter release at developing neuromuscular synapses. Neuron 6, 837-43.

Fu, W.M. and Huang, F.L. (1994) Potentiation by endogenously released ATP of spontaneous transmitter secretion at developing neuromuscular synapses in Xenopus cell cultures. Br. J. Pharmacol. 111, 880-6.

Funakoshi, H., Belluardo, N., Arenas, E., Yamamoto, Y., Casabona, A., Persson, H. and Ibanez, C.F. (1995) Muscle-derived neurotrophin-4 as an activity-dependent trophic signal for adult motor neurons. Science 268, 1495-9.

Gao, W.Q., Shinsky, N., Ingle, G., Beck, K., Elias, K.A. and Powell-Braxton, L. (1999) IGF-I deficient mice show reduced peripheral nerve conduction velocities and decreased axonal diameters and respond to exogenous IGF-I treatment. J. Neurobiol. 39, 142-52.

Giorgetti, S., Pelicci, P.G., Pelicci, G. and Van Obberghen, E. (1994) Involvement of Src-homology/collagen (SHC) proteins in signaling through the insulin receptor and the insulin-like-growth-factor-I-receptor. Eur. J. Biochem. 223, 195-202.

Griesbeck, O., Parsadanian, A.S., Sendtner, M. and Thoenen, H. (1995) Expression of neurotrophins in skeletal muscle: quantitative comparison and significance for motoneuron survival and maintenance of function. J. Neurosci. Res. 421, 21-33.

Hamill, O.P., Marty, A., Neher, E., Sakmann, B. and Sigworth, F.J. (1981) Improved patch-clamp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers. Arch. 391, 85-100.

Hammarberg, H., Risling, M., Hokfelt, T., Cullheim, S. and Piehl, F. (1998) Expression of insulin-like growth factors and corresponding binding proteins (IGFBP 1-6) in rat spinal cord and peripheral nerve after axonal injuries. J. Comp. Neurol. 400, 57-72.

Harish, O.E. and Poo, M.M. (1992) Retrograde modulation at developing neuromuscular synapses: involvement of G protein and arachidonic acid cascade. Neuron 9, 1201-9.

Hebb, D. (1949 ) The Organization of Behavior. New York: Wiley

Hong, F., Moon, Ka., Kim, S.S., Kim, Y.S., Choi, Y.K., Bae, Y.S., Suh, P.G., Ryu, S.H., Choi, E.J., Ha, J. and Kim, S.S. (2001) Role of phospholipase C-gamma1 in insulin-like growth factor I-induced muscle differentiation of H9c2 cardiac myoblasts. Biochem. Biophys. Res. Commun. 282, 816-22.

Hughes, R.A., Sendtner, M. and Thoenen, H. (1993) Members of several gene families influence survival of rat motoneurons in vitro and in vivo. J. Neurosci. Res. 36, 663-71.

Ishii, D.N. (1989) Relationship of insulin-like growth factor II gene expression in muscle to synaptogenesis. Proc. Natl. Acad. Sci. U. S. A. 86, 2898-902.

Ishii, D.N., G.W. Glazner, and L.R. Whalen. 1993. Regulation of peripheral nerve regeneration by insulin-like growth factors. Ann. N.Y. Acad. Sci. 692, 172-182.

Jones, J.I. and Clemmons, D.R. (1995) Insulin-like growth factors and their binding proteins: biological actions. Endocr. Rev. 16, 3-34.

Kar, S., Seto, D., Dore, S., Hanisch, U. and Quirion, R. (1997) Insulin-like growth factors-I and -II differentially regulate endogenous acetylcholine release from the rat hippocampal formation. Proc. Natl. Acad. Sci. U. S. A. 94, 14054-9.

Kim, B., Leventhal, P.S., Saltiel, A.R. and Feldman, E.L. (1997) Insulin-like growth factor-I-mediated neurite outgrowth in vitro requires mitogen-activated protein kinase activation. J. Biol. Chem. 272, 21268-73.

Kim, B., Cheng, H.L., Margolis, B. and Feldman, E.L. (1998) Insulin receptor substrate 2 and Shc play different roles in insulin-like growth factor I signaling. J. Biol. Chem. 273, 34543-50.

Kleiman, R.J., Tian, N., Krizaj, D., Hwang, T.N., Copenhagen, D.R. and Reichardt, L.F. (2000) BDNF-Induced potentiation of spontaneous twitching in innervated myocytes requires calcium release from intracellular stores. J. Neurophysiol. 84, 472-83.

Koistinen, R., Itkonen, O., Selenius, P. and Seppala, M. (1990) Insulin-like growth factor-binding protein-1 inhibits binding of IGF-I on fetal skin fibroblasts but stimulates their DNA synthesis. Biochem. Biophys. Res. Commun. 173, 408-15.

Konishi, Y., Takahashi, K., Chui, D.H., Rosenfeld, R.G., Himeno, M. and Tabira, T. (1994) Insulin-like growth factor II promotes in vitro cholinergic development of mouse septal neurons: comparison with the effects of insulin-like growth factor I. Brain Res. 649, 53-61.

Laufer, R. and Changeux J.P. (1987) Calcitonin gene-related peptide elevates cyclic AMP levels in chick skeletal muscle: possible neurotrophic role for a coexisting neuronal messenger. EMBO J. 6, 901-6.

Leski, M.L., Valentine, S.L., Baer, J.D. and Coyle, J.T. (2000) Insulin-like growth factor I prevents the development of sensitivity to kainate neurotoxicity in cerebellar granule cells. J. Neurochem. 75, 1548-56.

Li, Y.X., Zhang, Y., Lester, H.A., Schuman, E.M. and Davidson, N. (1998) Enhancement of neurotransmitter release induced by brain-derived neurotrophic factor in cultured hippocampal neurons. J. Neurosci. 18, 10231-40.

Liou, J.C. and Fu, W.M. (1997) Regulation of quantal secretion from developing motoneurons by postsynaptic activity-dependent release of NT-3. J. Neurosci. 17, 2459-68.

Lohof, A.M., Ip N.Y. And Poo, M.M. (1993) Potentiation of developing neuromuscular synapses by the neurotrophins NT-3 and BDNF. Nature 363, 350-3.

Lund, P.K., Moats-Staats, B.M., Hynes, M.A., Simmons, J.G., Jansen, M., D'Ercole, A.J. and Van Wyk, J.J. (1986) Somatomedin-C/insulin-like growth factor-I and insulin-like growth factor-II mRNAs in rat fetal and adult tissues. J. Biol. Chem. 261, 14539-44.

Megyesi, K., Kahn, C.R., Roth, J., Froesch, E.R., Humbel, R.E., Zapf, J. and Neville, D.M. Jr. (1974) Insulin and non-suppressible insulin-like activity (NSILA-s): evidence for separate plasma membrane receptor sites. Biochem. Biophys. Res. Commun. 57, 307-15.

Mehrhof, F.B., Muller, F.U., Bergmann, M.W., Li, P., Wang, Y., Schmitz, W., Dietz, R. and von Harsdorf R. (2001) In cardiomyocyte hypoxia, insulin-like growth factor-I-induced antiapoptotic signaling requires phosphatidylinositol-3-OH-kinase-dependent and mitogen-activated protein kinase-dependent activation of the transcription factor cAMP response element-binding protein. Circulation 104, 2088-94.

Mohan, S., Bautista, C.M., Wergedal, J. and Baylink, D.J. (1989) Isolation of an inhibitory insulin-like growth factor (IGF) binding protein from bone cell-conditioned medium: a potential local regulator of IGF action. Proc. Natl. Acad. Sci. U. S. A. 86, 8338-42.

Nastuk, M.A. and Fallon, J.R. (1993) Agrin and the molecular choreography of synapse formation. Trends Neurosci. 16, 72-6.

Nitkin, R.M., Smith, M.A., Magill, C., Fallon, J.R., Yao, Y.M, Wallace, B.G. and McMahan, U.J. (1987) Identification of agrin, a synaptic organizing protein from Torpedo electric organ. J. Cell Biol. 105, 2471-8.

Pierson. R.W. Jr. and Temin, H.M. (1972) The partial purification from calf serum of a fraction with multiplication-stimulating activity for chicken fibroblasts in cell culture and with non-suppressible insulin-like activity. J. Cell Physiol. 79, 319-30.

Pu, S.F., Zhuang, H.X., Marsh, D.J. and Ishii, D.N. (1999) Time-dependent alteration of insulin-like growth factor gene expression during nerve regeneration in regions of muscle enriched with neuromuscular junctions. Brain Res. Mol. Brain Res. 63, 207-16.

Rechler, M.M. and Nissley S.P. (1990) Insulin-like growth factors. In: Sporn M.B., Rober A.B.( eds ) Peptide Growth Factors and Their Receptors. Springer Verlag, Berlin, 263-367.

Recio-Pinto, E., Rechler, M.M. and Ishii, D.N. (1986) Effects of insulin, insulin-like growth factor-II, and nerve growth factor on neurite formation and survival in cultured sympathetic and sensory neurons. J. Neurosci. 6, 1211-9.

Rind, H.B. and von Bartheld, C.S. (2002) Target-derived cardiotrophin-1 and insulin-like growth factor-I promote neurite growth and survival of developing oculomotor neurons. Mol. Cell Neurosci. 19, 58-71.

Rinderknecht, E. and Humbel, R.E. (1976) Polypeptides with nonsuppressible insulin-like and cell-growth promoting activities in human serum: isolation, chemical characterization, and some biological properties of forms I and II. Proc. Natl. Acad. Sci. U. S. A. 73, 2365-9.

Ribchester, R.R., Thomson, D., Haddow, L.J. and Ushkaryov, Y.A. (1998) Enhancement of spontaneous transmitter release at neonatal mouse neuromuscular junctions by the glial cell line-derived neurotrophic factor (GDNF). J. Physiol. 512, 635-41.

Ross, M., Francis, G.L., Szabo, L., Wallace, J.C. and Ballard, F.J. (1989) Insulin-like growth factor (IGF)-binding proteins inhibit the biological activities of IGF-1 and IGF-2 but not des-(1-3)-IGF-1. Biochem. J. 258, 267-72.

Rotwein, P., Burgess, S.K., Milbrandt, J.D. and Krause, J.E. (1988) Differential expression of insulin-like growth factor genes in rat central nervous system. Proc. Natl. Acad. Sci. U. S. A. 85, 265-9.

Russell, J.W., Cheng, H.L. and Golovoy, D. (2000) Insulin-like growth factor-I promotes myelination of peripheral sensory axons. J. Neuropathol. Exp. Neurol. 59, 575-84.

Salmon, W.D. JR. and Dauaghaday, W.H. (1957) A hormonally controlled serum factor which stimulates sulfate incorporation by cartilage in vitro. J. Lab. Clin. Med. 49, 825-36.

Sanes, J.R. and Lichtman, J.W. (1999) Development of the vertebrate neuromuscular junction. Annu. Rev. Neurosci. 22,389-442.

Sasaoka, T., Rose, D.W., Jhun, B.H., Saltiel, A.R., Draznin, B. and Olefsky, J.M. (1994) Evidence for a functional role of Shc proteins in mitogenic signaling induced by insulin, insulin-like growth factor-1, and epidermal growth factor. J. Biol. Chem. 269, 13689-94.

Sasaoka, T., Ishiki, M., Wada, T., Hori, H., Hirai, H., Haruta, T., Ishihara, H. and Kobayashi, M. (2001) Tyrosine phosphorylation-dependent and -independent role of Shc in the regulation of IGF-1-induced mitogenesis and glycogen synthesis. Endocrinology 142, 5226-35.

Shatz, C.J. (1990) Impulse activity and the patterning of connections during CNS development. Neuron 5, 745-56.

Spitzer, N.C. and Lamborghini, J.E. (1976) The development of the action potential mechanism of amphibian neurons isolated in culture. Proc. Natl. Acad. Sci. U. S. A. 73, 1641-5.

Tabti, N. and Poo, M.M. ( 1991 ) Culturing spinal cord neurons and muscle cells from Xenopus embryos. In: Culturing nerve cells ( Banker G, Gosling K, eds ) pp 137-154. Cambridge, MA: MIT Press.

Torres-Aleman, I. (1999) Insulin-like growth factors as mediators of functional plasticity in the adult brain. Horm. Metab. Res. 31, 114-9.

Ui, M., Shimonaka, M., Shimasaki, S. and Ling, N. (1989) An insulin-like growth factor-binding protein in ovarian follicular fluid blocks follicle-stimulating hormone-stimulated steroid production by ovarian granulosa cells. Endocrinology 125, 912-6.

Usdin, T.B. and Fischbach, G.D. (1986) Purification and characterization of a polypeptide from chick brain that promotes the accumulation of acetylcholine receptors in chick myotubes. J. Cell. Biol. 103, 493-507.

Wang, X.H. and Poo, M.M. (1997) Potentiation of developing synapses by postsynaptic release of neurotrophin-4. Neuron 19, 825-35.

Wang, T., Xie, Z. and Lu, B. (1995) Nitric oxide mediates activity-dependent synaptic suppression at developing neuromuscular synapses. Nature 374, 262-6.

Werther, G.A., Abate, M., Hogg, A., Cheesman, H., Oldfield, B., Hards, D., Hudson, P., Power, B., Freed, K. and Herington, A.C. (1990) Localization of insulin-like growth factor-I mRNA in rat brain by in situ hybridization--relationship to IGF-I receptors. Mol. Endocrinol. 4, 773-8.

Xie, K., Wang, T., Olafsson, P., Mizuno, K. and Lu, B. (1997) Activity-dependent expression of NT-3 in muscle cells in culture: implications in the development of neuromuscular junctions. J. Neurosci. 17, 2947-58.

Ye, P., Umayahara, Y., Ritter, D., Bunting, T., Auman, H., Rotwein, P. and D'Ercole, A.J. (1997) Regulation of insulin-like growth factor I (IGF-I) gene expression in brain of transgenic mice expressing an IGF-I-luciferase fusion gene. Endocrinology 138, 5466-75.

You, H., Zheng, H., Murray, S.A., Yu, Q., Uchida, T., Fan, D. and Xiao, Z.X. (2002) IGF-1 induces Pin1 expression in promoting cell cycle S-phase entry. J. Cell. Biochem. 84, 211-6.

Young, S.H. and Poo, M.M. (1983) Spontaneous release of transmitter from growth cones of embryonic neurones. Nature 305, 634-7.

Zapf, J., Schoenle, E., Jagars, G., Sand, I., Grunwald, J. and Froesch, E.R. (1979) Inhibition of the action of nonsuppressible insulin-like activity on isolated rat fat cells by binding to its carrier protein. J. Clin. Invest. 63, 1077-84.

Zhang, L.I., Tao, H.W., Holt, C.E., Harris, W.A. and Poo, M. (1998) A critical window for cooperation and competition among developing retinotectal synapses. Nature 395, 37-44.