Metabolic profiles of canine cerebrovascular tree: a histochemical study

Acetylcholinesterase-containing fibers and choline acetyltransferase activity in isolated cerebral microvessels from goats

Microvessels have been isolated from goat cerebral cortex and caudate nucleus. The purity of the preparations was assessed by light microscopy and by the high enrichment in the marker enzymes alkaline phosphatase and gamma-glutamyltransferase. Choline acetyltransferase activity was detected in the vascular fractions, being significantly higher in capillaries than in larger vessels. Acetylcholinesterase (AChE)-containing fibers were visualized in vessels of different caliber. Vessels with diameters larger than 70-90 microns showed a network pattern of fibers similar to that of pial arteries. In small vessels (10-70 microns) longitudinal or helical fibers were observed with occasional side-branches that surround the vessel. No AChE staining was visualized in isolated capillaries under light microscopy. This study shows that isolated intracerebral microvessels are suitable preparations for histochemical studies of perivascular nerves. Taken together, the biochemical and histological results are in accordance with a cholinergic innervation of the goat intracerebral vasculature.

Thalamic arterial pattern: an endocast and scanning electron microscopic study in normotensive male rats

Rat cerebral vasculature serves as a model for study of the pathophysiology of stroke in humans. Human thalamic arteries show a high incidence of stroke. The objective is to describe the thalamic arterial vascular pattern in normotensive male rats as the initial step for quantitative histochemical studies of enzyme activities in the walls of these vessels. Intracardiac injections of methyl methacrylate monomer provide detailed vascular endocasts. The thalamic vascular bed defined by in situ dissection, serial reconstruction, and light and scanning electron microscopy of endocasts contained four groups of vessel: ventral medial thalamic arteries, thalamic branches from the posterior cerebral artery, and ventral lateral and ventral anterior thalamic arteries. Thalamic vessels are muscular arterioles that, after three to four bipinnate branches, feed into a continuous capillary bed (no loops). The parent vessels and their subsequent branches have been evaluated in terms of their mean internal diameters, mean interbranch intervals, and branch angles. The arterial patterns to rat and human thalami are very similar, with the exception of the anterior choroidal artery which is missing in the rat. The branches supplying the thalamus in both the rat and human are closely associated with the circle of Willis; however, the constituent parts of the circle in rat vary from the pattern in human brain. The rat thalamic arteries show morphological features similar to those seen in the stroke-prone ganglionic arteries in the human basal ganglia.

The terminal vascular bed in the superficial cortex of the rat. An SEM study of corrosion casts

The capillaries in the vascular bed of the rat brain have been investigated by means of scanning electron microscopy of corrosion casts. A technique is described that allowed the finer ramifications to be observed. A series of representative sites from the arteriovenous terminal pathway are described in detail. Contrary to previous reports, the dichotomic pattern of vessel distribution is shown to prevail over the network pattern. Arteriovenous shunts of discrete size were not seen. "Thoroughfare channels" could be recognized. The findings are considered in light of current physiological knowledge, and their significance for microcerebrovascular flow is indicated.

A histochemical examination of the metabolic profiles of rat ventral tegmental area and substantia nigra arterioles

To determine the metabolic profiles of arterioles of the rat ventral tegmental area and zona compacta and zona reticulata of the substantia nigra (SN), the distribution of selected enzymes, or by-products, of key metabolic pathways were examined histologically. Arterioles of all three regions expressed the enzymes required for aerobic and anaerobic metabolism. However, the relative abundance of the enzymes and byproducts suggests a lower metabolic capacity for the SN than the ventral tegmentum, while lipid catabolism in both regions appears non-operative. Moreover, the larger ventral tegmental arterioles possess a greater potential for nucleic acid and protein synthesis. Together, these results suggest the larger ventral tegmental arterioles possess a greater capacity for proliferation and repair.

A metabolic profile of the rat caudate microvasculature: a histochemical study

Arterioles of the rat caudate nucleus were examined histochemically to determine their metabolic profile. These microvessels appear capable of aerobic and anaerobic metabolism with a potential for nucleic acid and protein synthesis. Little intramural lipid storage occurs and any fatty acids utilized are provided via the blood supply. Likewise, glycogen is not seen in the arteriolar wall and may be rapidly turned over as a substrate for anaerobic metabolism.