Expressions and Distributions of Leucine-enkephalin, Delta, Mu, and Kappa Opioid Receptors in Four Systems of the Octopus, Octopus ocellatus by Comparative Immunohistochemical Method and ELISA

We have investigated the expressions and distributions of leucine-enkephalin (Leu-enk), delta (δ), mu (μ), kappa (κ) opioid receptors immunoreactivities in respiratory, circulatory, excretory reproductive systems Octopus, Octopus ocellatus, by comparative immunohistochemical method enzyme-linked immunosorbent assay (ELISA). The results showed that δ receptor Leu-enk were both detected branchia, ventricle, branchial heart, ovary oviducal gland, while was additionally gland kidneys less extend. majority examined tissues presented weak Leu-enk, with notable exception white body spermary found negative. No labellings μ κ observed O. ocellatus. combined indicated they may be involved regulations respiration, circulation, reproduction endocrine together other hormones or neurotransmitters ocellatus’ body. different densities ocellatus related to functions.