The brain is a complex organ in charge of regulating the homeostasis of our body and behaviors such as motivation, reward, memory, and movement control, between others. These behaviors are regulated by dopaminergic neurons, which can be modulated by several stimuli throughout the life of an individual. For example, early exposure to sex hormones or endocrine disruptors during critical period of neuronal development affects dopaminergic pathways permanently, producing some disorders such as drug addiction. On the other hand, current knowledge regarding neurodegeneration in Parkinson and Alzheimer diseases pointed out the neuroprotection that estradiol can exert, but contradictory information can also be found in the literature. To know the underlying mechanisms that are related to the above mentioned diseases will help to improve health policies and treatments development.
Part of the book: Sex Hormones in Neurodegenerative Processes and Diseases
The blood circulation interface and the neural tissue feature unique characteristics encompassed by the term blood -brain barrier (BBB). The barrier’s primary functions are maintenance of brain homeostasis, selective transport, and protection, all of them determined by its specialized multicellular structure. The BBB primarily exists at the level of the brain microvascular endothelium; however, endothelial cells are not intrinsically capable of forming a barrier. Indeed, the development of barrier characteristics in cerebral endothelial cells requires coordinated cell–cell interactions and signaling from glial cells (i.e., astrocytes, microglia), pericytes, neurons, and extracellular matrix. Such an intricate relationship implies the existence of a neurovascular unit (NVU). The NVU concept emphasizes that the dynamic BBB response to stressors requires coordinated interactions between various central nervous system (CNS) cell types and structures. Every cell type makes an indispensable contribution to the BBBs integrity, and any cell’s failure or dysfunction might result in the barrier breakdown, with dramatic consequences, such as neuroinflammation and neurodegeneration. This chapter will focus on the structure and function of the BBB and discuss how BBB breakdown causes detrimental brain function.
Part of the book: Connectivity and Functional Specialization in the Brain