Hormone complement of the Cancer productus sinus gland and pericardial organ: an anatomical and mass spectromelnc investigation, J.
In decapod Crustacea, neuromodulators are released into the hemolymph from two major neurosecretory structures: the sinus glands located in the eyestalks, and the pericardial organs (POs) in the pericardial cavity that surrounds the heart (Alexandrowicz, 1953; Cooke and Sullivan, 1982; Li et al., 2003; Billimoria et al., 2005; Fu et al., 2005).
Cells containing CHH-like peptides are also found in the pericardial organ and gastrointestinal tract of Carcinus maenas (Chung et al., 1999; Webster et al., 2000; Dircksen et al., 2001).
Crustacean hyperglycaemic hormone (CHH)-like peptides and CHH-precursor-related peptides from pericardial organ neurosecretory cells in the shore crab, Carcinus maenas, are putatively spliced and modified products of multiple genes.
In support of this type of action, pericardial organ extracts were found to increase cAMP levels in Homarus cardiac ganglia, and pharmacological manipulations that increased cAMP mimicked the effect of PO extracts (Lemos and Berlind, 1981), Manipulations expected to increase NO levels increased cGMP levels and inhibited activity of the CG, while decreasing NO synthase activity decreased cGMP levels and increased burst frequency (Labenia et al., 1998).
The sites of action of pericardial organ extract and 5-hydroxytryptamine in the decapod crustacean heart.
Crustacean cardioactive peptide (CCAP), originally isolated from pericardial organs of Carcinus maenas (Stangier et al., 1987), is another example of a neuropeptide with a wide, if not universal, occurrence in arthropods.
Biological effects of crustacean cardioactive peptide, a putative neurohormone/neurotransmitter from crustacean pericardial organs. Pp.
Heart rate ([f.sub.H]) is also modified by all of the neurohormones that have been identified in the pericardial organs (see reviews by Wilkens, 1987; Wilkens and McMahon, 1992).
Such factors could include neurohormonal secretions from the pericardial organs lining the pericardial cavity and metabolite end products produced during walking.
In crustaceans, FMRFamide-like immunoreactivity has been found throughout the nervous system, the highest amounts being concentrated in the pericardial organs (Kobierski et al., 1987; Marder et al., 1987; Trimmer et al., 1987; Krajniak, 1991; Mercier et al., 1991).
Future work will focus on the sites of action of these peptides to ascertain their role in cardioregulation, and measurement of circulating levels will determine whether they are released from the pericardial organs in amounts sufficient to effect the reported changes.