Immunocytochemical Localization of Enzymes Involved in Dopamine, Serotonin, and Acetylcholine Synthesis in the Optic Neuropils and Neuroendocrine System of Eyestalks of Paralithodes camtschaticus

Abstract

Identifying the neurotransmitters secreted by specific neurons in crustacean eyestalks is crucial to understanding their physiological roles. Here, we combined immunocytochemistry with confocal microscopy and identified the neurotransmitters dopamine (DA), serotonin (5-HT), and acetylcholine (ACh) in the optic neuropils and X-organ sinus gland (XO-SG) complex of the eyestalks of Paralithodes camtschaticus (red king crab). The distribution of Ach neurons was studied by choline acetyltransferase (ChAT) immunohistochemistry and compared with that of DA neurons examined in the same or adjacent sections by tyrosine hydroxylase (TH) immunohistochemistry. We detected 5-HT, TH, and ChAT in columnar, amacrine, and tangential neurons in the optic neuropils and established the presence of immunoreactive fibers and neurons in the terminal medulla in the XO region of the lateral protocerebrum. Additionally, we detected ChAT and 5-HT in the endogenous cells of the SG of P. camtschaticus for the first time. Furthermore, localization of 5-HT- and ChAT-positive cells in the SG indicated that these neurotransmitters locally modulate the secretion of neurohormones that are synthesized in the XO. These findings establish the presence of several neurotransmitters in the XO-SG complex of P. camtschaticus.

Neurochemical diversity in the central olfactory pathway of the crustacean Parhyale hawaiensis (Amphipoda): evolutionary implications

“…Only a few examples describe antisera staining for ChAT in crustaceans, for example, in the barnacle Balanus amphitrite (Gallus et al., 2006), and in the nervous system of Hemigrapsus sanguineus (Kotsyuba & Dyachuk, 2021) and Paralithodes camschaticus (Kotsyuba & Dyachuk, 2022). However, ChAT staining is well established in D. melanogaster (Seki et al., 2010; Shang et al., 2007; Yasuyama et al., 1995) and other insects like Manduca sexta (Clark et al., 2005; Torkkeli et al., 2005) and Periplanta americana (Fusca et al., 2015).…”

“…Only a few examples describe antisera staining for ChAT in crustaceans, for example, in the barnacle Balanus amphitrite (Gallus et al, 2006), and in the nervous system of Hemigrapsus sanguineus (Kotsyuba & Dyachuk, 2021) and Paralithodes camschaticus (Kotsyuba & Dyachuk, 2022). However, ChAT staining is well established in D.…”

3D Optical Reconstruction of the Nervous System of the Whole-Body Marine Invertebrates

“…Therefore, we have changed some protocol settings and introduced additional steps for immuno-coloring and the optical clearing of the earlier (zoea I) and late-stage (zoea IV) king crab larvae Paralithodes camtschaticus equipped with maxims and mandibles (Table 2). 49 An additional step of decalcification with EDTA and bleaching with H 2 O 2 significantly improved the immunostainings of the neurostructure and increased the transparency of the whole-body of larvae. As a result, neurostructure of the larvae has been easily observed using confocal microscopy after immunostaining with synapsin and nuclei (Dapi) (Figure 7).…”