Regulation of Morphological and Functional Aspects of Sexual Dimorphism in the Brain

Sexual dimorphism of the adult brain regulates sex-dependent functions including reproductive and neuroendocrine activities in rodents. It is determined by sex steroid hormones during a critical perinatal period in female and male rodents. Sex steroids act on each nuclear receptor in the brain and control different physiological and neuroendocrine functions and behaviors. Several regions of the brain show evident morphological sex differences that are involved in their physiological functions. This review addresses and focuses largely on the role of sex-dependent differences in the brain, and their crucial functions in animal models. Particularly, recent intriguing data concerning the diversity of neuronal functions and sexual dimorphism are discussed

Neural Contributions of the Hypothalamus to Parental Behaviour

Parental behaviour is a comprehensive set of neural responses to social cues. The neural circuits that govern parental behaviour reside in several putative nuclei in the brain. Melanin concentrating hormone (MCH), a neuromodulator that integrates physiological functions, has been confirmed to be involved in parental behaviour, particularly in crouching behaviour during nursing. Abolishing MCH neurons in innate MCH knockout males promotes infanticide in virgin male mice. To understand the mechanism and function of neural networks underlying parental care and aggression against pups, it is essential to understand the basic organisation and function of the involved nuclei. This review presents newly discovered aspects of neural circuits within the hypothalamus that regulate parental behaviours

Induction of oocyte-nurse cell differentiation in the ovary by the brain during the initial stage of oogenesis in the silkworm, Bombyx mori (Lepidoptera: Bombycidae)

Co-culture of ovarian cells in young larvae with brain induced meiosis and endomitosis of the silkworm, Bombyx mori. This suggests that a substance secreted by the brain controls meiosis and endomitosis. When preparations from Bombyx heads were tested for meiosisinducing activity, both the crude and highly purified preparations of bombyxin induced meiosis in vitro, but the crude preparation of prothoracicotropic hormone (PTTH) showed much lower activity. This indicates that bombyxin is the brain substance that induces meiosis. 20-Hydroxyecdysone also induced meiosis, but only at a low concentration

Induction of oocyte-nurse cell differentiation in the ovary by the brain during the initial stage of oogenesis in the silkworm, Bombyx mori (Lepidoptera: Bombycidae)

Co-culture of ovarian cells in young larvae with brain induced meiosis and endomitosis of the silkworm, Bombyx mori. This suggests that a substance secreted by the brain controls meiosis and endomitosis. When preparations from Bombyx heads were tested for meiosisinducing activity, both the crude and highly purified preparations of bombyxin induced meiosis in vitro, but the crude preparation of prothoracicotropic hormone (PTTH) showed much lower activity. This indicates that bombyxin is the brain substance that induces meiosis. 20-Hydroxyecdysone also induced meiosis, but only at a low concentration