Galanin-immunoreactive neuronal system and colocalization with serotonin in the optic lobe and peduncle complex of the octopus (Octopus vulgaris).
Immunohistochemical techniques were used to investigate the distribution of galanin-like immunoreactivity and colocalization with serotonin (5-HT) in the optic lobe and peduncle complex of the octopus, Octopus vulgaris. Galanin immunoreactive (Gal-IR) fibers, but not cells, were seen in the plexiform layer of the optic lobe cortex. Gal-IR cells were scattered in the cell-islands of the optic lobe medulla and Gal-IR varicose fibers were observed to be abundant in the neuropil surrounding the islands. All Gal-IR cells were immunoreactive for 5-HT, and a few cells showed only 5-HT-like immunoreactivity. In the peduncle lobe, no Gal-IR cells were seen in the basal zone or spine, but in the basal zone, many Gal-IR fibers were seen. In the anterior olfactory lobule, only a few pyramidal Gal-IR cells were observed in the cell layer, and their apical processes were traced to the central neuropil. In the median olfactory lobule, ovoid Gal-IR cells were scattered in the peripheral cell layer. All Gal-IR cells in the anterior and median olfactory lobules showed 5-HT-like immunoreactivity. In the posterior olfactory lobule, ovoid and triangular Gal-IR cells were scattered in the cell layer. Some of them showed 5-HT-like immunoreactivity. Western blot analysis indicated an Gal-IR band at approximately 15.4 kDa. These results suggest the association of galanin-like substance and 5-HT with the visual system of octopus and that the main form of the octopus galanin might have a different molecular weight from vertebrate galanins.
Suzuki
H
H
Department of Biology, Fukuoka University of Education, 729-1 Akama, 811-4192, Munakata, Japan. spiderhs@fukuoka-edu.ac.jp
Yamamoto
T
T
Inenaga
M
M
Uemura
H
H
D000818:Animals; D005260:Female; D019004:Galanin / Q000378:metabolism*; D008297:Male; D049831:Octopodiformes / Q000033:anatomy & histology / Q000378:metabolism*; D009899:Optic Lobe, Nonmammalian / Q000033:anatomy & histology / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism*
D012701:Serotonin; D019004:Galanin