title: Perinatal testosterone exposure is critical for the development of the male-specific sexually dimorphic gastrin-releasing peptide system in the lumbosacral spinal cord that mediates erection and ejaculation.
abstract: BACKGROUND
  In rats, a sexually dimorphic spinal gastrin-releasing peptide (GRP) system in the lumbosacral spinal cord projects to spinal centers that control erection and ejaculation. This system controls the sexual function of adult males in an androgen-dependent manner. In the present study, we assessed the influence of androgen exposure on the spinal GRP system during a critical period of the development of sexual dimorphism.
  
  
  METHODS
  Immunohistochemistry was used to determine if the development of the spinal GRP system is regulated by the perinatal androgen surge. We first analyzed the responses of neonates administered with anti-androgen flutamide. To remove endogenous androgens, rats were castrated at birth. Further, neonatal females were administered androgens during a critical period to evaluate the development of the male-specific spinal GRP system.
  
  
  RESULTS
  Treatment of neonates with flutamide on postnatal days 0 and 1 attenuated the spinal GRP system during adulthood. Castrating male rats at birth resulted in a decrease in the number of GRP neurons and the intensity of neuronal GRP in the spinal cord during adulthood despite testosterone supplementation during puberty. This effect was prevented if the rats were treated with testosterone propionate immediately after castration. Moreover, treating female rats with androgens on the day of birth and the next day, masculinized the spinal GRP system during adulthood, which resembled the masculinized phenotype of adult males and induced a hypermasculine appearance.
  
  
  CONCLUSIONS
  The perinatal androgen surge plays a key role in masculinization of the spinal GRP system that controls male sexual behavior. Further, the present study provides potentially new approaches to treat sexual disorders of males.
authors.affiliation: Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, 130-17 Kashino, Ushimado, Setouchi, Okayama 701-4303 Japan.
authors.forename: Takumi
authors.initials: T
authors.lastname: Oti
authors.affiliation: Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, 130-17 Kashino, Ushimado, Setouchi, Okayama 701-4303 Japan.
authors.forename: Keiko
authors.initials: K
authors.lastname: Takanami
authors.affiliation: Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, 130-17 Kashino, Ushimado, Setouchi, Okayama 701-4303 Japan.
authors.forename: Nao
authors.initials: N
authors.lastname: Katayama
authors.affiliation: Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, 130-17 Kashino, Ushimado, Setouchi, Okayama 701-4303 Japan.
authors.forename: Tomoca
authors.initials: T
authors.lastname: Edey
authors.affiliation: Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, 130-17 Kashino, Ushimado, Setouchi, Okayama 701-4303 Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Satoh
authors.affiliation: Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, 130-17 Kashino, Ushimado, Setouchi, Okayama 701-4303 Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Sakamoto
authors.affiliation: Ushimado Marine Institute (UMI), Graduate School of Natural Science and Technology, Okayama University, 130-17 Kashino, Ushimado, Setouchi, Okayama 701-4303 Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Sakamoto
keywords: Androgens; Gastrin-releasing peptide; Male sexual function; Sexual differentiation; Spinal cord