Neuronal nitric oxide synthase and gonadal steroid interaction in the MPOA of male rats: Co-localization and testosterone-induced restoration of copulation and nNOS-immunoreactivity

• Published in: Brain research 2005-05, Vol.1043 (1), p.205-213
• Main Authors: Sato, Satoru, Braham, Claudean S., Putnam, Susan K., Hull, Elaine M.
• Format: Article
• Language: English
• Subjects: Androgen receptor; Androgens - metabolism; Androgens - pharmacology; Animals; Biological and medical sciences; Copulation - drug effects; Copulation - physiology; Estrogen receptor; Estrogen Receptor alpha - metabolism; Fundamental and applied biological sciences. Psychology; Hormone metabolism and regulation; Immunohistochemistry; Male; Male sexual behavior; Mammalian male genital system; Medial preoptic area (MPOA); Nerve Tissue Proteins - metabolism; Neurons - enzymology; Nitric oxide synthase (NOS); Nitric Oxide Synthase - metabolism; Nitric Oxide Synthase Type I; Paraventricular Hypothalamic Nucleus - metabolism; Preoptic Area - cytology; Preoptic Area - drug effects; Preoptic Area - metabolism; Rats; Rats, Long-Evans; Receptors, Androgen - metabolism; Testosterone - metabolism; Testosterone - pharmacology; Vertebrates: reproduction
• ISSN: 0006-8993; 1872-6240
• DOI: 10.1016/j.brainres.2005.02.074

Neuronal nitric oxide synthase (nNOS) in the medial preoptic area (MPOA) has been implicated in various physiological functions, including male rat copulation. Based on their apparent sensitivity to gonadal steroid manipulation, we hypothesized that nNOS cells contain steroid receptors, and the testosterone-induced restoration of nNOS-immunoreactivity in castrates should accompany the restoration of copulation. In Experiment 1, we investigated co-localization of nNOS with the androgen receptor (AR) and the estrogen receptor alpha (ERα) using immunocytochemistry. We found regionally specific co-localizations of nNOS-AR and nNOS-ERα. In Experiment 2, we investigated the relationship between MPOA nNOS-immunoreactivity (ir) and copulatory measures in the testosterone-induced restoration paradigm in castrates. The restoration of various copulatory measures was accompanied by an increase in optical density of nNOS-ir, but not in the number of nNOS-ir cells. These data provide additional evidence supporting the role of MPOA nitric oxide in male rat copulation.