Neurturin has multiple neurotrophic effects on adult rat sacral parasympathetic ganglion neurons.
Neurturin (NTN) is an important neurotrophic factor for parasympathetic neurons; however, no studies to date have investigated the signalling mechanisms downstream of GFRalpha2 and Ret activation underlying this neurotrophic support. This is particularly important for pelvic parasympathetic neurons, which are prone to injury during surgical procedures such as prostatectomy, and where there are no current therapies for axonal regeneration. To address this issue we have cultured dissociated adult rat pelvic ganglion neurons and also examined the structural changes in pelvic ganglion neurons after axotomy. Axotomised penile neurons deprived of target-derived support had smaller somata than intact neurons. Studies of cultured adult pelvic ganglion neurons also demonstrated that NTN stimulated soma growth. Further experiments showed that NTN reduced the up-regulation of tyrosine hydroxylase expression in cultured pelvic parasympathetic neurons. NTN stimulated the extension of neurites in cultured parasympathetic, but not sympathetic, pelvic ganglion neurons. Inhibition of phosphatidylinositol 3-kinase prevented initiation of neurite outgrowth, whereas inhibition of the mitogen-activated protein kinase and the Src family kinase pathways disrupted NTN-stimulated microtubule assembly. Surprisingly, NTN did not activate the transcription factor cAMP-response element binding protein (CREB), which is typically involved in neurotrophic signalling in sympathetic neurons. This is the first study to identify signalling pathways activated by NTN in adult parasympathetic neurons. Our results may lead to a better understanding of regenerative mechanisms in parasympathetic neurons, especially for those innervating urogenital organs. Our results also indicate that neurotrophic signalling in parasympathetic neurons is different from that in other types of peripheral neurons.
Wanigasekara
Yewlan
Y
Prince of Wales Medical Research Institute, University of New South Wales, Randwick NSW 2031, Australia.
Keast
Janet R
JR
D000818:Animals; D019771:Axotomy / Q000379:methods; D048429:Cell Size / Q000187:drug effects; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005726:Ganglia, Parasympathetic / Q000166:cytology*; D005786:Gene Expression Regulation / Q000187:drug effects; D007150:Immunohistochemistry / Q000379:methods; D008297:Male; D009414:Nerve Growth Factors / Q000494:pharmacology*; D016501:Neurites / Q000187:drug effects; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D051101:Neurturin; D019001:Nitric Oxide Synthase / Q000378:metabolism; D010413:Penis / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D012445:Sacrococcygeal Region; D013997:Time Factors; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D017362:Cyclic AMP Response Element-Binding Protein; D004791:Enzyme Inhibitors; D009414:Nerve Growth Factors; D051101:Neurturin; C495057:Nrtn protein, rat; D005576:Colforsin; D019001:Nitric Oxide Synthase; D014446:Tyrosine 3-Monooxygenase