Effect of excitatory amino acid receptor agonists on penile erection after administration into paraventricular nucleus of hypothalamus in the rat.
OBJECTIVE
To investigate whether the excitatory amino acid receptor agonists can activate the paraventricular nucleus of the hypothalamus (PVN) and induce penile erections in the rat.


METHODS
Male adult Sprague-Dawley rats were used. A 26-gauge needle was inserted into the corpus cavernosum to monitor the intracavernous pressure (ICP) simultaneously with the systemic arterial pressure and heart rate. The study was divided into seven parts: stereotaxic delivery of N-methyl-d-aspartic acid (NMDA) (50 ng/500 nL) into the PVN; administration of the NMDA noncompetitive antagonist MK-801 (100 ng/250 nL) and NMDA (50 ng/250 nL) into the PVN; administration of the NMDA competitive antagonist (+/-)-3-(2-carboxypiperazin-4-yl)-propyl-1-phosphonic acid (CPP; 100 ng/250 nL) and NMDA (50 ng/250 nL) into the PVN; microinjection of (+/-)-alpha-(amino)-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA; 100 ng/500 nL) into the PVN; microinjection of trans-(+/-)-1-amino-1,3-cyclopentanedicarboxylic acid (ACPD; 100 ng/500 nL) into the PVN; saline 500 nL into the PVN; and intracavernous administration of NMDA (50 ng/100 microL).


RESULTS
On administration of NMDA into the PVN, a significant increase occurred in the ICP from a resting 8.3 +/- 1.8 mm Hg to a peak at 59.0 +/- 8.4 mm Hg. No change occurred in the resting ICP after administration of either the mixture of MK-801 and NMDA or CPP and NMDA into the PVN. Microinjection of AMPA, ACPD, or saline into the PVN and intracavernous administration of NMDA were all ineffective to induce an increase in ICP.


CONCLUSIONS
The results of this study suggest that ionotropic excitatory amino acid (NMDA) may have an effect on inducing penile erection through activation of the PVN in the rat.
Chen
Kuang-Kuo
KK
Division of Urology, Department of Surgery, Taipei Veterans General Hospital, Taiwan, People's Republic of China.
Chang
Luke S
LS
D000818:Animals; D016291:Dizocilpine Maleate / Q000008:administration & dosage; D018690:Excitatory Amino Acid Agonists / Q000008:administration & dosage*; D008297:Male; D016202:N-Methylaspartate / Q000008:administration & dosage*; D010286:Paraventricular Hypothalamic Nucleus / Q000187:drug effects* / Q000502:physiology; D010410:Penile Erection / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000008:administration & dosage
D018690:Excitatory Amino Acid Agonists; D016202:N-Methylaspartate; D016291:Dizocilpine Maleate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid