Olfactory sense is an essential modality for insects to locate hosts, mates, oviposition sites, and food resources in nature. Based on many studies so far, insect olfactory systems in periphery as well as central nervous systems seem to be highly plastic with behavioral and physiological changes associated with learning and memory, sensory processes, and other developmental processes. Eventually, it is also evident that these plasticity and processes in olfactory systems are modulated by a various ensemble or sets of neuropeptides. The olfactory reception in the peripheral systems of the cockroach, Periplaneta americana, associated with learning behaviors, is fluctuated by the circadian rhythm, which is subsequently thought to control the titer of hormones and various neuropeptides concomitantly. However, it remains still elusive how neuropeptides and neuroendocrine systems modulate olfactory system in the peripheral systems in cockroaches as well as any other insects. Here, our aims to characterize the ultrastructure of these neuro-endocrine systems in the peripheral olfactory systems in American cockroach, Periplaneta americana. Using in situ hybridization methods, we found out that tachykinin and its receptors seem to be important neurotransmission machineries in the periphery to convey the arousal signals from the insect brain. Our findings also indicate complicated endocrine systems connected with central nervous systems may modulate the olfactory reception in the periphery.