Vitamin D3 analogues (VD3) are among the most prominent neurosteroids. Their importance in neural development, neuroprotection and control of mood and behaviour has been extensively studied. In addition to the well known involvement in systemic calcium homeostasis VD3 plays a pivotal role in numerous brain functions. Developmental disturbances like autism or attention-deficit hyperactivity syndrome (ADHS) and degenerative ailments including Alzheimer’s or Parkinsons disease have been shown to correspond with low VD3 levels. Seasonal depression and related affective disorders can be effectively treated with VD3. Recent studies indicate that VD3 may even act as pheromones in various species including humans. Vitamin D is known to act through nuclear steroid vitamin D receptor (VDR). Rapid VD3 actions mediated through membrane effects may be equally important. We could show that membrane-associated VDR is linked to vitamin D-binding globulin (DBG). Expression of both proteins is different in various brain regions and malleable to functional status.