Abstract
BackgroundThe role of the endothelial cell (EC) in blood flow regulation within the central nervous system has been little studied. Here, we explored EC participation in morphological changes of the anterior hypothalamic paraventricular nucleus (PVN) microvasculature of female rats at two reproductive stages with different metabolic demand (virginity and lactation). We measured the inner capillary diameter (ICD) of 800 capillaries from either the magnocellular or parvocellular regions. The space occupied by neural (somas, dendrites and axons) and glial, but excluding vascular elements of the neurovascular compartment was also measured in 100-μm2 sample fields of both PVN subdivisions.ResultsThe PVN of both groups of animals showed ICDs that ranged from 3 to 10 microns. The virgin group presented mostly capillaries with small ICD, whereas the lactating females exhibited a significant increment in the percentage of capillaries with larger ICD. The space occupied by the neural and glial elements of the neurovascular compartment did not show changes with lactation.ConclusionsOur findings suggest that during lactation the microvasculature of the PVN of female rats undergoes dynamic, transitory changes in blood flow as represented by an increment in the ICD through a self-cytoplasmic volume modification reflected by EC changes. A model of this process is proposed.
Highlights
The role of the endothelial cell (EC) in blood flow regulation within the central nervous system has been little studied
This visualization through light microscopy is based on two facts: first, the optical effect that reflecting light produces in fixed and unstained capillaries, and second, evidence provided by Electron microscopy (EM) [24,25] showing that the internal wall of central nervous system (CNS) capillaries is exclusively constituted by the endothelial cell
The Lactating group (LAC) group showed an inner capillary diameter (ICD) distribution that ranged from 4 to 10 μm in both regions, with most capillaries located in the 7-μm range followed by the 8- and 6-μm ranges, respectively
Summary
The role of the endothelial cell (EC) in blood flow regulation within the central nervous system has been little studied. Despite attempts to obtain markers enabling CNS capillary imaging or visualization of capillary networks through extracellular tracers, fluorescent markers, diamine benzidine reaction, immunocytochemistry as well as brain arterial injection with black ink or venous plastic infusion [1,15,22,23,24,26], a complete view of the morphology of CNS capillaries still is lacking In this respect, recently we proposed an alternative histological tool focused on detecting the relative space occupied by the capillary endothelial cell [27,28]. Using this procedure we found that changes in capillary luminal area can be detected indirectly via changes in the inner capillary diameter (ICD)
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