Mapping of octopamine‐immunoreactive neurons in the central nervous system of the lobster

Abstract

It has been suggested that serotonin and octopamine serve important roles in behavioral regulation in lobsters. In this paper the locations of octopamine-immunoreactive neurons were mapped in wholemount preparations of the ventral nerve cord of 4th stage lobster (Homarus americanus) larvae. Approximately 86 neurons were found, distributed as follows: brain, 12; circumesophageal ganglia, 2; subesophageal ganglion, 38; thoracic ganglia, 6 each; and 4th and 5th abdominal ganglia, 2 each. All the octopamine-immunoreactive neurons are paired and located along the midline. Of the 86 neurons, 28 were identified as neurosecretory, and 26 as intersegmental ascending thoracic, ascending abdominal, or descending interneurons. The neurosecretory system is arranged segmentally and located entirely within the thoracic and subesophageal neuromeres with extensive terminal fields of endings along 2nd thoracic and subesophageal nerve roots. This set of neurons shares the features of central and peripheral endings with 2 pairs of large serotonin-containing neurosecretory neurons found in the fifth thoracic and first abdominal ganglia. The intersegmental neurons include: (1) two cells in the brain and 2 pairs of cells in the 3rd and 4th neuromeres of the subesophageal ganglion, which project to the 6th abdominal ganglion; (2) a segmentally organized group of ascending interneurons found in the subesophageal and in all thoracic ganglia; and (3) pairs of ascending interneurons found in the 4th and 5th ganglia in the abdominal nerve cord. By means of a biochemical assay, the cell bodies of octopamine-immunoreactive neurosecretory cells in the thoracic segment of the nerve cord were found to contain 40-100 fmol of octopamine, while control neurons had none.

Octopamine immunoreactivity in the fruit fly Drosophila melanogaster

“…To test the specificity of the antibody, we preincubated the antiserum (1:1,000) with 5 × 10 −3 M DL-octopamine from Sigma at 4°C for 24 hours (Schneider et al, 1993). Control larval CNSs were then incubated with preabsorbed primary antibody and were processed as described above.…”

“…Certain octopaminergic DUM neurons have also been revealed by the sulphide silver-staining method, which detects endogenous copper, a cofactor of the octopamine biosynthetic enzyme tyramine β-hydroxylase (Siegler et al, 1991). Recently, antibodies highly specific to octopamine have been developed that facilitate more definitive mapping of octopaminergic neurons in the nervous systems of several animals (Konings et al, 1988;Eckert et al, 1992;Stevenson et al, 1992;Schneider et al, 1993).In Drosophila melanogaster, there is good evidence that the amines octopamine, 5-HT, and dopamine are utilized in the nervous system (reviewed by Restifo and White, 1990). For example, electrophysiological studies suggest effects of octopamine on the adult neuromuscular junction (Dudai et al, 1987).…”

“…Samples for whole-mount immunocytochemistry were dehydrated, cleared in methylsalicylate, and mounted in Permount. Fourteen adult heads, 6 adult thoracic, and 17 larval CNS preparations were analyzed for OA-IR ncuronal patterns.To test the specificity of the antibody, we preincubated the antiserum (1:1,000) with 5 × 10 −3 M DL-octopamine from Sigma at 4°C for 24 hours (Schneider et al, 1993). Control larval CNSs were then incubated with preabsorbed primary antibody and were processed as described above.…”

“…Certain octopaminergic DUM neurons have also been revealed by the sulphide silver-staining method, which detects endogenous copper, a cofactor of the octopamine biosynthetic enzyme tyramine β-hydroxylase (Siegler et al, 1991). Recently, antibodies highly specific to octopamine have been developed that facilitate more definitive mapping of octopaminergic neurons in the nervous systems of several animals (Konings et al, 1988;Eckert et al, 1992;Stevenson et al, 1992;Schneider et al, 1993).…”

Plasticity and Second Messengers During Synapse Development

“…FMRFamide-related peptides-The Drosophila FMRFamide gene encodes as many as 15 neuropeptides (Nambu et al, 1988) which are synthesized, and potentially secreted into the hemolymph from neurosecretory organs localized in the dorsal region of the CNS, but not from nerve terminals at the NMJ (Schneider et al, 1993). Assay of a large group of these peptides at the NMJ showed that they had essentially redundant functionality, enhancing twitch tension presumably by increasing EJC amplitude (Hewes et al, 1998).…”