Terminal abdominal ganglion

It is imperative to demonstrate whether JH HI operates directly on pheromone glands or whether it facilitates the activity of other pheromonotropic regulators. Studies of mated females, which produce JH III but not pheromone, have made it abundantly clear that unknown regulatory elements downstream of the action of JH must be involved. These factors probably interact with inhibitory signals from the terminal abdominal ganglion that ascend the VNC and control CNS activity. A concerted effort is needed to identify neuropeptides and other factors that activate and terminate pheromone production, emission, and sexual receptivity. 

Pheromone production in females of many species of moths is controlled by a hormone, the pheromone biosynthesis activating neuropeptide (PBAN). PBAN was isolated from Helicoverpa Heliothls ) zea and identified as a 33 amino acid peptide. Amidation of the C-terminus is important for the biological activity of this hormone. Oxidation of two Met residues at postitions 5 and 14 enhanced pheromonotropic activity of PBAN. Stability of PBAN in saline can be increased by the substitution of Nle for Met at positions 5 and 14. Biological activity is mostly associated with brain-suboesophageal ganglion and corpora cardiaca of both female and male moths. Terminal abdominal ganglion does not appear to be directly involved in the control of pheromone production. PBAN is slowly degraded in hemolymph. Future possibilities of research on PBAN are discussed. 

Figure 5. Pheromonotropic activity associated with (1) brain-suboesophageal ganglion, (2) corpora cardiaca-corpora allata (3) thoracic ganglia (4) three anterior abdominal ganglia (5) terminal abdominal ganglion and...

Table I. Role of terminal abdominal ganglion in pheromone production in ligated Helicoverpa zea females...

Voltage clamp experiments using identified neurons, dorsal unpaired median (DUM) neurons from the terminal abdominal ganglion of P. americana, demonstrated that DCJW inhibited the peak Na+ current with an IC50 of 28 nM [38]. DCJW (7) (100 mv[) induced a hyperpolarization of DUM neurons associated with block of background Na channels involved in maintenance of the resting potential. While the peak Na+ current was inhibited, DCJW had no effect on either activation or inactivation kinetics (Fig. 29.4.13). Zhao et al. (2005) similarly... 

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