Sympathetic nerves are sparsely distributed in rat mesenteric perivascular adipose tissue.

Area of Science:

• Vascular Biology
• Adipose Tissue Biology
• Neuroscience

Background:

• Perivascular adipose tissue (PVAT) influences blood vessel function.
• Sympathetic neural input to PVAT is proposed to modulate this effect.
• The extent of PVAT innervation by the sympathetic nervous system is not fully understood.

Purpose of the Study:

• To investigate the sympathetic innervation of rat mesenteric PVAT.
• To examine PVAT in Dahl-salt sensitive (Dahl-SS) rats, a model for hypertension.
• To determine if tyrosine hydroxylase (TH)-positive nerves are present in mesenteric PVAT.

Main Methods:

• Whole-mount immunofluorescence staining of mesenteric PVAT, arteries, and small intestine.
• Antibodies against tyrosine hydroxylase (TH) and CD-31 (PECAM) were used.
• Confocal microscopy and image analysis quantified nerve and vessel labeling.

Main Results:

• Limited TH-positive nerve innervation was found in mesenteric PVAT of Sprague-Dawley and Dahl-SS rats.
• Most TH-positive nerves were observed along small blood vessels within the PVAT.
• Strong TH-positive nerve labeling was present on mesenteric resistance arteries, distinct from PVAT.
• CD-31 labeling confirmed antibody penetration and vascular presence.

Conclusions:

• Mesenteric PVAT exhibits sparse innervation by TH-positive sympathetic nerves.
• Sympathetic nerve control of individual PVAT adipocytes appears limited.
• Nerves primarily associate with blood vessels within the PVAT rather than adipocytes themselves.