title: Tx2-6 toxin of the Phoneutria nigriventer spider potentiates rat erectile function.
abstract: The venom of the spider Phoneutria nigriventer contains several toxins that have bioactivity in mammals and insects. Accidents involving humans are characterized by various symptoms including penile erection. Here we investigated the action of Tx2-6, a toxin purified from the P. nigriventer spider venom that causes priapism in rats and mice. Erectile function was evaluated through changes in intracavernosal pressure/mean arterial pressure ratio (ICP/MAP) during electrical stimulation of the major pelvic ganglion (MPG) of normotensive and deoxycorticosterone-acetate (DOCA)-salt hypertensive rats. Nitric oxide (NO) release was detected in cavernosum slices with fluorescent dye (DAF-FM) and confocal microscopy. The effect of Tx2-6 was also characterized after intracavernosal injection of a non-selective nitric oxide synthase (NOS) inhibitor, L-NAME. Subcutaneous or intravenous injection of Tx2-6 potentiated the elevation of ICP/MAP induced by ganglionic stimulation. L-NAME inhibited penile erection and treatment with Tx2-6 was unable to reverse this inhibition. Tx2-6 treatment induced a significant increase of NO release in cavernosum tissue. Attenuated erectile function of DOCA-salt hypertensive rats was fully restored after toxin injection. Tx2-6 enhanced erectile function in normotensive and DOCA-salt hypertensive rats, via the NO pathway. Our studies suggest that Tx2-6 could be important for development of new pharmacological agents for treatment of erectile dysfunction.
authors.affiliation: Departamento de Fisiologia e Biofisica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais , Belo Horizonte, Minas Gerais, Brazil.
authors.forename: K P
authors.initials: KP
authors.lastname: Nunes
authors.forename: A
authors.initials: A
authors.lastname: Costa-Gonçalves
authors.forename: L F
authors.initials: LF
authors.lastname: Lanza
authors.forename: S F
authors.initials: SF
authors.lastname: Cortes
authors.forename: M N
authors.initials: MN
authors.lastname: Cordeiro
authors.forename: M
authors.initials: M
authors.lastname: Richardson
authors.forename: A M C
authors.initials: AM
authors.lastname: Pimenta
authors.forename: R C
authors.initials: RC
authors.lastname: Webb
authors.forename: R
authors.initials: R
authors.lastname: Leite
authors.forename: M E
authors.initials: ME
authors.lastname: De Lima
mesh_terms: D000818:Animals; D004195:Disease Models, Animal; D004357:Drug Synergism; D004558:Electric Stimulation; D007172:Erectile Dysfunction / Q000150:complications / Q000188:drug therapy / Q000503:physiopathology; D006973:Hypertension / Q000139:chemically induced / Q000150:complications / Q000503:physiopathology; D008297:Male; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009479:Neuropeptides / Q000302:isolation & purification / Q000494:pharmacology*; D009498:Neurotoxins / Q000302:isolation & purification / Q000494:pharmacology*; D009569:Nitric Oxide / Q000378:metabolism; D010410:Penile Erection / Q000187:drug effects* / Q000502:physiology; D010413:Penis / Q000187:drug effects* / Q000294:innervation / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013111:Spider Venoms / Q000494:pharmacology*; D013112:Spiders
chemical_list: D009479:Neuropeptides; D009498:Neurotoxins; D013111:Spider Venoms; C076902:Tx2 neurotoxin; D009569:Nitric Oxide; D019331:NG-Nitroarginine Methyl Ester