Involvement of Vasoactive Intestinal Peptide (VIP) as a Humoral Mediator of Penile Erectile Function in the Dog

AOKI, HIKARU; MATSUZAKA, JUNICHI; YEH, KANG‐HSIUNG; SATO, FUMIO; FUJIOKA, TOMOAKI; KUBO, TAKASHI; OHHORI, TSUTOMU; YASUDA, NAOKI

doi:10.1002/j.1939-4640.1994.tb00426.x

Cited by 12 publications

References 28 publications

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Participation of Vasoactive Intestinal Polypeptide (VIP) as a Humoral Mediator in the Erectile Response of Canine Corpus Cavernosum Penis

YEH,

AOKI,

MATSUZAKA

et al. 1994

Journal of Andrology

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The ability of anti‐vasoactive intestinal peptide (anti‐VIP) serum to suppress the electrically induced relaxation of the corpus cavernosum was evaluated in vitro to define the role of VIP in penile erection. Strips of canine corpora cavernosa were placed in 5‐ml organ chambers containing oxygenated Krebs‐Ringer solution. They were stretched and fixed in place at both ends and pretreated with 2 × 10−7 M noradrenaline (NA). NA was given to produce an optimal state of isometric smooth muscle contraction so that subsequent electrical field stimulation (EFS) could induce a good range of measurable relaxation response. This response was deemed to be an in vitro representation of penile erection. After NA treatment the cavernous tension rose markedly by 2–2.5 g; it then declined by up to 1–1.2 g upon EFS. Anti‐VIP serum (1:16) or atropine sulfate (10−6 M) was added at various time points between NA administration and EFS. When anti‐VIP serum was administered, subsequent EFS‐induced relaxation was attenuated by 20%–55% compared to the control EFS treatments. The degree of attenuation depended upon the frequency of EFS applied, being 20.6% ± 4.0% at 20 Hz and 54.7% ± 6.3% at 2 Hz. Atropine administered additionally following anti‐VIP serum produced no further attenuation. However, atropine alone was capable of producing up to 23.7% ± 3.5% attenuation. When anti‐VIP serum was administered following atropine, the degree of attenuation that ensured was the sum of the attenuations produced by each of the two substances independently. These results indicated that both VIP and acetylcholine were involved in the EFS‐induced erectile response, the contribution of the former being greater than that of the latter. A considerable portion of the EFS‐induced cavernous relaxation, however, appeared to be dependent on factors other than VIP and acetylcholine.

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Participation of Vasoactive Intestinal Polypeptide (VIP) as a Humoral Mediator in the Erectile Response of Canine Corpus Cavernosum Penis

YEH,

AOKI,

MATSUZAKA

et al. 1994

Journal of Andrology

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Suppressive Effects of Chronic Hyperprolactinemia on Penile Erection and Yawning Following Administration of Apomorphine to Pituitary‐Transplanted Rats

SATO,

AOKI,

NAKAMURA

et al. 1997

Journal of Andrology

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Recent studies showed in vivo and in vitro that acutely introduced prolactin (PRL) excess was capable of diminishing penile erectile function independently of the LH‐testosterone (T) dynamics. In the present investigation, we examined if such independent suppressive effects can be demonstrated in the pituitary‐transplant rat model with chronically elevated serum PRL. We also compared the effects of pituitary transplantation and castration on the level of erectile activity. Rats were made hyperprolactinemic by homologous transplantation of three anterior pituitaries underneath the kidney capsules, with the eutopic pituitaries left in situ. Before and 3,5, and 8 weeks after transplant or sham surgeries, 80 μg/kg s.c. injection of apomorphine was given as an inducer of erection. This was followed by 30‐minute observation periods during which the numbers of erections and yawning were recorded. Similar experiments were also performed with castrated rats without transplanted pituitaries. In the transplanted rats, plasma PRL was markedly elevated (51.4 ± 3.7 ng/ml) and was significantly (P < 0.001) higher than the values in the sham group (6.0 ± 2.7 ng/ml). In contrast, plasma T was not different (P > 0.05) between the two groups. The castrated rats showed very low plasma T (0.17 ± 0.01 ng/ml, P < 0.05 compared to the sham group) and normal PRL (P > 0.05). The numbers of both erection and yawning were significantly (P < 0.05 ∼0.01) less in the transplant than in the sham group 8 weeks after surgeries. Castrated rats showed a significant reduction (P < 0.05) only in the numbers of erection. These results indicated that the pituitary transplantation with chronic excess of PRL and castration with T deficiency caused roughly comparable degrees of suppression of penile erectile activity through mechanisms presumably independent from one another in the rat.

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Neurochemistry of Male Sexual Behavior

Hull¹,

Domínguez²,

Muschamp³

2007

Handbook of Neurochemistry and Molecular Neurobiology

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Involvement of Vasoactive Intestinal Peptide (VIP) as a Humoral Mediator of Penile Erectile Function in the Dog

Cited by 12 publications

References 28 publications

Participation of Vasoactive Intestinal Polypeptide (VIP) as a Humoral Mediator in the Erectile Response of Canine Corpus Cavernosum Penis

Participation of Vasoactive Intestinal Polypeptide (VIP) as a Humoral Mediator in the Erectile Response of Canine Corpus Cavernosum Penis

Suppressive Effects of Chronic Hyperprolactinemia on Penile Erection and Yawning Following Administration of Apomorphine to Pituitary‐Transplanted Rats

Neurochemistry of Male Sexual Behavior

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