title: Intraocular production and release of nerve growth factor after iridectomy.
abstract: OBJECTIVE
  To determine the presence of nerve growth factor (NGF), NGF mRNA, and NGF receptor (TrkA) in rabbit ocular tissues, and whether changes occur in NGF and NGF mRNA levels after experimental iridectomy.
  
  
  METHODS
  Immunohistochemistry for NGF and TrkA and in situ hybridization for NGF mRNA were performed on rabbit cornea, iris, ciliary body, and lens in the basal state. Quantification of NGF mRNA and NGF protein levels in these tissues was performed by RT-PCR and immunoenzymatic assay, respectively. A time course of NGF concentration in the aqueous humor and the expression of NGF mRNA in iris and ciliary body were performed after the iridectomy and were compared with levels in a sham-treated group (paracentesis).
  
  
  RESULTS
  Cornea, iris, ciliary body, and lens expressed NGF mRNA, NGF protein, and TrkA in the basal state. The highest levels of NGF were detected in the iris (8938.0 +/- 3968.1 pg/g), and the lowest were in the aqueous humor (22.8 +/- 9.7 pg/mL). Experimental iridectomy induced a transient increase of NGF concentration in the aqueous humor that reached its peak 4 hours after the experimental injury (464.4 +/- 29.9 pg/mL versus the control group 101.6 +/- 18.8 pg/mL; P < 0.001) and returned to baseline value after 7 days. A significant increase of NGF mRNA was also observed 1 hour and 4 hours after the iridectomy in the iris (1 hour, 788 +/- 85 OD; 4 hours, 760 +/- 81 OD versus baseline, 246 +/- 32 OD; P < 0.0001) and ciliary body (1 hour, 330 +/- 19 OD; 4 hours, 453 +/- 52 OD versus baseline, 219 +/- 37 OD; P < 0.05), but not in the cornea, lens, or any tissues from the control group.
  
  
  CONCLUSIONS
  NGF is present and produced in the anterior segment of the eye and is released in the aqueous humor in the basal state. Experimental iridectomy induces increased production of NGF in the iris and in the ciliary body and an increased concentration of NGF in the aqueous humor.
authors.affiliation: Department of Ophthalmology, University of Rome Tor Vergata, Rome, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Lambiase
authors.forename: Stefano
authors.initials: S
authors.lastname: Bonini
authors.forename: Luigi
authors.initials: L
authors.lastname: Manni
authors.forename: Emiliano
authors.initials: E
authors.lastname: Ghinelli
authors.forename: Paola
authors.initials: P
authors.lastname: Tirassa
authors.forename: Paolo
authors.initials: P
authors.lastname: Rama
authors.forename: Luigi
authors.initials: L
authors.lastname: Aloe
mesh_terms: D000818:Animals; D001082:Aqueous Humor / Q000378:metabolism; D002924:Ciliary Body / Q000378:metabolism; D003315:Cornea / Q000378:metabolism; D007124:Immunoenzyme Techniques; D017403:In Situ Hybridization; D007498:Iris / Q000378:metabolism* / Q000601:surgery*; D008297:Male; D020932:Nerve Growth Factor / Q000235:genetics / Q000378:metabolism*; D013508:Ophthalmologic Surgical Procedures; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D020917:Receptor, trkA / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D012333:RNA, Messenger; D020932:Nerve Growth Factor; D020917:Receptor, trkA