title: Involvement of L-arginine/nitric oxide pathway at the paraventricular nucleus of hypothalamus in central neural regulation of penile erection in the rat.
abstract: The objective of this study is to investigate whether the L-arginine/nitric oxide pathway is involved in the neurotransmission of paraventricular nucleus of hypothalamus (PVN) activation-induced penile erection in the rat. Male adult Sprague-Dawley rats anesthetized with pentobarbital were used. The femoral artery was cannulated to measure systemic and mean arterial pressure (SAP and MAP), and heart rate (HR). A 26-gauge needle was inserted into corpus cavernosum to measure the intracavernous pressure (ICP) simultaneously with SAP, MAP and HR on a polygraph. Four groups of study were arranged: (1) stereotaxically delivery of L-arginine (500 nmol/500 nl) into PVN; (2) administration of a mixture (1 microl) containing N(G)-Nitro-L-arginine methyl ester (L-NAME) 500 nmol and L-arginine 500 nmol into PVN; (3) microinjection of saline 500 nl into PVN as a vehicle control; and (4) intracavernous injection of L-arginine (100 nmol/50 microl). The ICP, SAP, MAP and HR were monitored for at least 2 h after each administration of the experimental agents. Upon administration of L-arginine into PVN, there was a significant increase of ICP from resting 9.6+/-2.5 mmHg to peaked at 64.4+/-9.8 mmHg after a latency of 3016.0+/-1749.7 s and with a duration of 27.6+/-15.8 min. There was no change of resting ICP after administration of the mixture of L-NAME and L-arginine into PVN. Application of saline to PVN and intracavernous injection of L-arginine failed to increase ICP. Based on elicitation of penile erection upon administration of L-arginine into PVN, and elimination of this L-arginine induced penile erection by co-administration of L-NAME with L-arginine, the results of this study suggest that L-arginine/nitric oxide pathway may be involved in the neurotransmission of PVN activation-induced penile erection in the rat.
authors.affiliation: Division of Urology, Department of Surgery, Taipei Veterans General Hospital, Taipei, Taiwan, Republic of China. kkchen@vghtpe.gov.tw
authors.forename: K K
authors.initials: KK
authors.lastname: Chen
authors.forename: L S
authors.initials: LS
authors.lastname: Chang
mesh_terms: D000818:Animals; D001120:Arginine / Q000008:administration & dosage / Q000378:metabolism* / Q000494:pharmacology; D004338:Drug Combinations; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008297:Male; D008845:Microinjections; D019331:NG-Nitroarginine Methyl Ester / Q000008:administration & dosage / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism*; D010286:Paraventricular Hypothalamic Nucleus / Q000502:physiology*; D010410:Penile Erection / Q000187:drug effects / Q000502:physiology*; D010413:Penis / Q000187:drug effects / Q000502:physiology; D011312:Pressure; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D004338:Drug Combinations; D004791:Enzyme Inhibitors; D009569:Nitric Oxide; D001120:Arginine; D019331:NG-Nitroarginine Methyl Ester