About this Research Topic
The role of insulin in the brain has been suggested in the late 1950’s based on experiments showing that insulin was able to increase glucose uptake in spinal cord tissue and radioactive phosphorus in several brain regions such as choroid plexus, epiphysis and hypophysis. These early studies suggested that glucose metabolism in some specific brain areas was most likely insulin dependent. Since then, increasing evidence attributed to insulin action in the brain numerous critical roles in the control of vital physiological functions: energy homeostasis, neuronal plasticity and growth, lipid and glucose metabolism through the control of peripheral organs. Furthermore, the alteration of insulin action observed in insulin resistant state or obesity is now considered a risk factor for several pathologies including neurodegenerative diseases and metabolic disorders. Nowadays many studies aim to decipher the mechanisms of insulin action in different brain regions and the related physio-pathological outputs. Indeed, this Research Topic aims to collect the latest findings concerning insulin action in the brain and will cover the following points:
Origin of brain insulin: The presence of insulin in brain extracts has risen very early the question whether insulin has a peripheral origin or is produced by the Central Nervous System (CNS). The peripheral origin of insulin has been evidenced by its uptake through blood-brain barrier (BBB) using a specific transport system coupled to insulin receptor in cerebral vessels. The central origin of insulin is still matter of controversy, however, several studies reported the presence of C-peptide and pro-insulin in the CNS. In addition, pre-proinsulin I and insulin II mRNAs have been detected in different brain locations. These findings have been confirmed in cultured neurons.
Insulin signaling in the brain: Since 1970s, insulin receptor expression in the brain has been evidenced by autoradiography using 125I-insulin. Using more modern methods and techniques based on the binding studies, RT-PCR and in situ hybridization, the insulin receptor expression has been confirmed and revealed a distinct expression pattern in the CNS. Furthermore all components of insulin signaling have been characterized in the brain such as IRS/PI3kinase/Akt and Erk1/2 pathways.
Insulin roles in the brain: As peripheral insulin, brain insulin is implicated in major physiological regulations such as: energy homeostasis and weight control, cognition and memory, reproduction, neurogenesis and neuromodulation.
In this Research Topic we welcome original research and reviews articles. Expected contributions will cover all aspects cited above, in particular:
- Mechanisms of insulin uptake by the brain.
- Insulin expression and synthesis in the brain.
- Insulin signaling in different brain regions.
- Insulin and neuronal plasticity.
- Impact of insulin on cognition and memory.
- Insulin and neurodegenerative diseases.
- Role of insulin in the regulation of the reproductive system.
- Neurotrophic action of insulin: neuronal proliferation and differentiation.
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.