What are lipoproteins doing in the brain?

Abstract

Lipoproteins in plasma transport lipids between tissues, however, only high density lipoproteins (HDL) appear to traverse the blood brain barrier; thus, lipoproteins found in the brain must be produced within the central nervous system. Apolipoproteins E (ApoE) and ApoJ are the most abundant apolipoproteins in the brain, are mostly synthesized by astrocytes and are found on HDL. In the hippocampus and other brain regions lipoproteins help regulate neurobehavioral functions by processes that are lipoprotein receptor-mediated. Moreover, lipoproteins and their receptors also have roles in the regulation of body weight and energy balance, i.e. through lipoprotein lipase (LPL) and the LDL receptor-related protein (LRP). Thus, understanding lipoproteins and their metabolism in the brain provides a new opportunity with potential therapeutic relevance.

High-Density Lipoproteins in Stroke

“…Various studies have described the capacity of the brain to synthesise lipoproteins that are different from plasma lipoproteins (for review, see Wang and Eckel 2014). Lipoproteins found in the cerebrospinal fluid (CSF) mainly originate from astrocytes and are characterised by a small size (resembling the size and density of HDLs) and contain mainly apo E (Ladu et al 2000;Koch et al 2001).…”

Lipoproteins and Diseases of the Brain

“…Lipoproteins in the brain are involved in the onset and progression of neurodegenerative diseases (e.g., Alzheimer's disease) [1,2] and neuroinflammatory disorders (e.g., neuroborreliosis) [3,4]. These lipoproteins are either endogenously expressed by astrocytes [5] and microglia [6,7] or exogenously produced by bacterial pathogens (e.g., Borrelia burgdorferi, Streptococcus pneumoniae) [8].…”

“…The most abundant endogenous lipoproteins in the brain include apolipoprotein E (apoE) and apoJ [2]. These endogenous lipoproteins mediate transport of lipids between various cells in the brain to maintain and regulate the brain structure and function [9,10].…”

Rôle de la détection centrale des lipides dans le contrôle nerveux de la balance énergétique

“…En effet, en permettant l'hydrolyse des lipoprotéines riches en triglycérides, comme les VLDL (very low density lipoprotein) ou les chylomicrons, cette enzyme entraîne un apport local d'acides gras vers les neurones « sensibles » [11]. En dehors de l'hypothalamus, la LPL interviendrait aussi dans l'hippocampe [9] et dans le noyau accumbens, comme régulateur de la balance énergétique [12], ces structures jouant respectivement un rôle dans les processus d'apprentissage et de motivation.…”

“…En dehors de l'hypothalamus, la LPL interviendrait aussi dans l'hippocampe [9] et dans le noyau accumbens, comme régulateur de la balance énergétique [12], ces structures jouant respectivement un rôle dans les processus d'apprentissage et de motivation. Ainsi, ces données mettent en lumière un effet éventuel de la détection des lipides dans des processus « non homéos-tatiques » de régulation de la prise alimentaire et de la balance énergétique [11].…”