Pattern of adrenergic innervation of aorta in goat (Capra Hircus)

Abstract

Adrenergic innervation of aorta influences its physicomechanical properties and functioning. The pattern may vary between species. The goat is a suitable model for studying cardiovascular disease, but the pattern of its innervation is largely unreported. The purpose of this study was therefore to describe the pattern of adrenergic innervation of its aorta. Aortae for this study were obtained from four adult male goats (capra hircus). Specimens were obtained immediately after euthanasia from ascending aorta, aortic arch, proximal (T6), middle (T9), distal (T12) thoracic and abdominal aorta. Fresh 2 mm long transverse specimens were embedded using OCT compound (Tissue-Tek II) in cryostat chamber at –30 °C. Cut sections were prepared for demonstration of tissue monoamines by the sucrose-potassium phosphate-glyoxylic acid (SPG) method. Examination under Leitz-Ortholux © fluorescent microscope revealed that adrenergic innervation is dense in the proximal segments where nerve terminals penetrate into the tunica media and colocalise with muscle islands present in the adventitial half. Density of innervation declines caudally such that in the abdominal aorta, there are only sparse terminals confined to the media-adventitial border. This dense adrenergic innervation of goat aorta and its regional variation may underpin regional differences in physicomechanical properties, functions and disease distribution in this vesse