THE PRODUCTION OF AN ANTISERUM TO SEROTONIN AND SEROTONIN-LIKE IMMUNOREACTIVITY IN THE COCKROACH BRAIN-MIDGUT SYSTEM

Abstract

A highly potent antiserotonin antiserum was prepared by injecting formaldehydecoupled serotonin-bovine serum albumin conjugate to the rabbit, together with the Freund’s complete adjuvant. Mouse intestinal enterochromaffin cells were stained with this antiserum at the dilution up to 1 : 50,000. The antiserum proved specific against serotonin in situ, though cross-reactivity with related compounds particularly with dopamine was seen in vitro. With this antiserum, serotonin-like immunoreactivity in the cockroach brain-midgut endocrine system was seen in: one large and eight to ten small cells bilaterally located in the pars intercerebralis, two cell groups ventral to the calyx, three pairs of a single cell in the suboesophageal ganglion, one cell in the thoracic ganglia, and one cell group in the terminal ganglion. These neurons extend many fibers widely distributed in the central nervous system, especially in the protocerebral bridge, central body and neuropiles of the deutocerebrum. The frontal ganglion, and the nerves innervating the longitudinal muscle fibers of the midgut showed serotonin-like reactivity, but this was not specific. Some endocrine cells in the midgut showed immunoreactivity to serotonin, but its specificity could not be determined because of an extremely small population of these cells.