Eur J Anat, 20 (2): 113-120 (2016)

Brain sexual development in Kallmann syndrome

Leandro Castañeyra-Ruiz^1,3, Emilia M. Carmona-Calero^1,2, Ibrahim González-Marrero¹, Juan M. González-Toledo¹, Agustín Castañeyra-Perdomo^1,2, Francisco J. Perez-Molto⁴

¹Departamento de Anatomía, Facultad de Medicina, Universidad de La Laguna, La Laguna, Tenerife, Islas Canarias, Spain, ²Instituto de Investigación y Ciencias de Puerto del Rosario, Puerto del Rosario, Fuerteventura, Islas Canarias, Spain, ³Departamento de Farmacología, Facultad de Medicina, Universidad de La Laguna, La Laguna, Tenerife, Islas Canarias, Spain, ⁴Dpto. de Anatomía y Embriología Humana, Facultad de Medicina, Universidad de Valencia,Valencia, Spain

ABSTRACT Prenatal and one-two month postnatal testosterone influences human neural and behavioural development, since the prenatal and one-two month postnatal hormone environment clearly contributes to the development of sex-related variation in human behaviour, and plays a role in the development of the sexual brain and individual differences in behaviour within each sex, as well as differences between the sexes. Olfactory system development, brain sexual maturation and sexual behaviour in man and animals are closely related. Kallmann syndrome (KS) is a genetic disorder which combines hypogonadotropic hypogonadism and anosmia. Hypogonadism is characterized by the absence or reduced levels of gonadotropin-releasing hormone, and anosmia is due to aplasia of the olfactory bulb. The overlap between the formation of the olfactory system and the migration of neurons that synthesize the gonadotropin-releasing hormone (GnRH) is common knowledge. GnRH neurons migrate from the medial portion of the nasal epithelium through the olfactory nerves and the main olfactory bulb to the anterior hypothalamus. Furthermore, the clinical manifestations of KS are: anosmia, the absence of puberty, and modifications in sexual behaviour. The structures responsible for the maturation of the main and accessory olfactory systems, the sexual differentiation of the brain and its relationship with clinical manifestations and sexual behaviour in Kallmann syndrome are analyzed in this review. The importance of the treatment of KS at early ages is suggested in order to improve brain sexual development and its clinical and sexual behaviour manifestations.

Keywords: Encephalic sexual maturation, Main and accessory olfactory systems, Kallmann syndrome, Sexual behaviour