Functional studies on neuropeptides and receptors in model animal <italic>Aplysia</italic>

Abstract

Neuropeptides are widely distributed in the central nervous system and the endocrine system. As signaling transduction molecules between cells, neuropeptides play important roles in regulating a variety of physiological processes, such as behavioral control, temperature regulation, energy balance, circadian rhythm. In this paper, we primarily review the discoveries and functions of neuropeptides that are released by neuronal elements in behavior-generating neural circuits in the central nervous system. Due to the complexity of neural circuits, it has been highly challenging to study all or most of the neuropeptides and their functions in a specific system in vertebrates.Consequently, many invertebrates have been used as model animals to discover novel neuropeptides and their receptors, and to study the functions of these neuropeptides and receptors. We describe the basic characteristics, modes of actions, and research approaches, particularly the progress of neuropeptide research in the experimentally-advantageous mollusc Aplysia. We highlight the diversity of neuropeptide/receptor signaling systems and the challenges in studying them. We believe that the findings in invertebrates will provide novel insights for the research on the functions and mechanisms of neuropeptides in vertebrates, including mammals.

AI protein structure prediction-based modeling and mutagenesis of a protostome receptor and peptide ligands reveal key residues for their interaction

“…Neuropeptides are the most diverse class of neuromodulators in both protostomes and deuterostomes (1)(2)(3)(4)(5). Neuropeptides primarily act on G protein-coupled receptors (GPCRs) to influence a variety of behaviors and physiological processes, including feeding, locomotion and reproduction.…”

Functional characterization of a neuropeptide receptor exogenously expressed in Aplysia neurons

“…Thus, relatively simple model systems, such as Aplysia , with identifiable neurons in well-defined neural circuits [3-10, 12, 14-17, 21, 22, 24-36] have been used in these studies. Earlier studies in model systems have focused on identifying neuropeptides and their bioactivity [2,34,35,[37][38][39][40][41][42][43][44][45][46][47].…”

“…Neuropeptides are the most diverse class of neurotransmitters/neuromodulators, which mostly act on G-protein coupled receptors (GPCRs). The diversity arises in part from the possibility that a single neuropeptide precursor can generate multiple forms of active peptides, and a peptide can act on multiple GPCRs, which in turn might function through different signaling pathways [1, 2]. Consequently, it has been challenging to study peptide signaling systems in vertebrates.…”

“…Thus, relatively simple model systems, such as Aplysia [3-28], with identifiable neurons in well-defined neural circuits [3-10, 12, 14-17, 21, 22, 24-36] have been used in these studies. Earlier studies in model systems have focused on identifying neuropeptides and their bioactivity [2, 34, 35, 37-47]. Recently, growing genetic information in model systems is becoming available and has facilitated studying of both neuropeptides and their receptors [36, 48-52].…”