Neuroendocrine regulatory peptide-1 and neuroendocrine regulatory peptide-2 influence differentially feeding and penile erection in male rats: sites of action in the brain.

Bernard B Brodie Department of Neuroscience and Centre of Excellence for the Neurobiology of Addictions, University of Cagliari, and Institute of Neuroscience, National Research Council, Cagliari Section, 09042 Monserrato, Cagliari, Italy.
Regulatory Peptides (Impact Factor: 2.06). 05/2012; 177(1-3):46-52. DOI: 10.1016/j.regpep.2012.04.007
Source: PubMed

ABSTRACT The effect of NERP-1 and NERP-2, two recently discovered VGF-derived peptides, on feeding and penile erection was studied after injection into the lateral ventricles, the lateral hypothalamus, the arcuate nucleus or the paraventricular nucleus of the hypothalamus. NERP-2 (1-5 nmol), but not NERP-1 (2-4 nmol), increased feeding in a dose-dependent manner when injected into the lateral ventricles or bilaterally into the lateral hypothalamus but not into the arcuate or the paraventricular nucleus. The effect of NERP-2 given into the lateral ventricles was found in the first, but not in the second 60 min after treatment, and was antagonized by SB-408124, an orexin-1 receptor antagonist given into the lateral ventricles or the arcuate nucleus, but not into the paraventricular nucleus. However, SB-408124 was unable to reduce NERP-2-induced feeding when injected bilaterally into the lateral hypothalamus before NERP-2 given also bilaterally into the lateral hypothalamus. In contrast, NERP-1, but not NERP-2, induced penile erection in a dose-dependent manner when injected into the lateral ventricles or the arcuate nucleus, but not into the paraventricular nucleus or the lateral hypothalamus. The pro-erectile effect of NERP-1 was not prevented by the prior injection of d(CH(2))(5)Tyr (Me)(2)-Orn(8)-oxytocin or SB-408124 into the lateral ventricles. The present results suggest that while NERP-2 facilitates feeding by acting in the lateral hypothalamus, possibly by increasing orexin activity in the arcuate nucleus, NERP-1 facilitates penile erection by acting in the arcuate nucleus with a mechanism not related to orexin or oxytocin.

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    ABSTRACT: Of the numerous neuropeptides identified in the central nervous system, only a few are involved in the control of sexual behavior. Among these, the most studied are oxytocin, adrenocorticotropin, α-melanocyte stimulating hormone and opioid peptides. While opioid peptides inhibit sexual performance, the others facilitate sexual behavior in most of the species studied so far (rats, mice, monkeys and humans). However, evidence for a sexual role of gonadotropin-releasing hormone, corticotropin releasing factor, neuropeptide Y, galanin and galanin-like peptide, cholecystokinin, substance P, vasoactive intestinal peptide, vasopressin, angiotensin II, hypocretins/orexins and VGF-derived peptides are also available. Corticotropin releasing factor, neuropeptide Y, cholecystokinin, vasopressin and angiotensin II inhibit, while substance P, vasoactive intestinal peptide, hypocretins/orexins and some VGF-derived peptide facilitate sexual behavior. Neuropeptides influence sexual behavior by acting mainly in the hypothalamic nuclei (i.e., lateral hypothalamus, paraventricular nucleus, ventromedial nucleus, arcuate nucleus), in the medial preoptic area and in the spinal cord. However, it is often unclear whether neuropeptides influence the anticipatory phase (sexual arousal and/or motivation) or the consummatory phase (performance) of sexual behavior, except in a few cases (e.g., opioid peptides and oxytocin). Unfortunately, scarce information has been added in the last 15 years on the neural mechanisms by which neuropeptides influence sexual behavior, most studied neuropeptides apart. This may be due to a decreased interest of researchers on neuropeptides and sexual behavior or on sexual behavior in general. Such a decrease may be related to the discovery of orally effective, locally acting type V phosphodiesterase inhibitors for the therapy of erectile dysfunction.
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