Leu-enkephalin and somatostatin immunoreactivities in canine and equine pheochromocytomas.

This research investigates the presence of leu-enkephalin and somatostatin in tumors called pheochromocytomas found in the adrenal glands of dogs and horses, and provides microscopic evidence of their occurrence therein.

Introduction

• The study focuses on pheochromocytoma, the most common tumor found in the adrenal medulla of domestic animals. This type of tumor originates from chromaffin cells in the adrenal medulla which typically produce substances called epinephrine and norepinephrine.
• Recent research has shown that there may be other substances present in the adrenal glands and the pheochromocytomas, including somatostatin and the enkephalins, in addition to the traditionally acknowledged secretory products, epinephrine and norepinephrine.
• The article seeks to document the presence of two particular substances—with an emphasis on leu-enkephalin and somatostatin—within the cells of these tumors.

Methodology

• The scientists conducted autopsy on a 13-year-old mixed breed dog, which had shown no signs of illness before its sudden death, and a 16-year-old pony that had clinical signs of hyperadrenalcorticism.
• The tissues were fixed in formalin, processed, embedded in paraffin and stained with hematoxylin and eosin for light microscopy.
• For electron microscopy, the tissues were treated with glutaraldehyde and osmium tetroxide, then processed, embedded in araldite, sectioned, and further stained with uranyl acetate and lead citrate.
• Immunohistochemical staining was carried out on the paraffin-embedded tissues after deparaffinizing and clearing them in ethanol. They were then hydrated and incubated in normal swine serum with an optimal dilution for anti-somatostatin and leu-enkephalin respectively.

Objective

• The main objective of this study was to demonstrate the presence of leu-enkephalin and somatostatin in pheochromocytomas in dogs and horses using both light and electron microscopy, advancing our understanding of the composition of these tumors.