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Nitric oxide production is increased in the paraventricular nucleus of the hypothalamus of male rats during non‐contact penile erections and copulation
Author(s) -
Melis Maria Rosaria,
Succu Salvatora,
Mauri Alessandro,
Argiolas Antonio
Publication year - 1998
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.1998.00207.x
Subject(s) - nitric oxide , hypothalamus , microdialysis , endocrinology , medicine , chemistry , nucleus , arginine , methylene blue , nitric oxide synthase , penis , central nervous system , biology , anatomy , neuroscience , biochemistry , amino acid , photocatalysis , catalysis
Male rats put in the presence of a receptive female rat that they can see, hear and smell, but cannot touch, show penile erection episodes. These non‐contact erections occur concomitantly with an increase in nitric oxide production in the paraventricular nucleus of the hypothalamus, as detected by the increase in the NO 2 – and NO 3 – concentration in the paraventricular dialysate obtained from these males by in vivo microdialysis. NO 2 – concentration increased from 0.81 ± 0.12 to 2.51 ± 0.43 μ m and that of NO 3 – from 4.50 ± 0.73 to 8.31 ± 2.3 μ m . The NO 2 – increase was prevented by the nitric oxide synthase inhibitor N G –nitro‐ l ‐arginine methylester (20 μg) given unilaterally in the paraventricular nucleus, which also prevented non‐contact erections. In contrast, the nitric oxide scavenger haemoglobin (20 μg) prevented the NO 2 – increase, but not non‐contact erections; while the guanylate cyclase inhibitor methylene blue (20 μg) was ineffective on either response. NO 2 – and NO 3 – concentration was also increased in the paraventricular dialysate of male rats during in copula penile erections, that is, when sexual activity was allowed with the receptive females. As found with non‐contact erections, N G –nitro‐ l ‐arginine methylester prevented NO 2 – increase and impaired copulatory behaviour; haemoglobin prevented NO 2 – increase only; and methylene blue was ineffective on either response. The present results confirm that nitric oxide is a physiological mediator of penile erection at the level of the paraventricular nucleus of the hypothalamus.