Physiological systems, neuropeptides action

The majority of insect neuropeptides discovered thus far seem to have the property of regulating the contractile activity of either skeletal and/or visceral muscles. Whether these are the principal or auxiliary modes of action for a given peptide must await a more comprehensive assessment of their individual profiles of activity in a variety of physiological systems. What follows is a summary of our current understanding of the physiological and pharmacological properties of the insect neuropeptides that regulate muscle activity. 

Examples of neuropeptides are endorphins and enkephalins, sometimes called naturally occurring opioid peptides because of their ability to bind to the same receptors as morphine. In this family of neuropeptides, there are at least 10 to 15 substances with purported actions on such diverse physiological systems as pain response, memory and learning, appetite, and temperature regulation. 

CCK is found in the digestive tract and the central and peripheral nervous systems. In the brain, CCK coexists with DA. In the peripheral nervous system, the two principal physiological actions of CCK are stimulation of gaU. bladder contraction and pancreatic enzyme secretion. CCK also stimulates glucose and amino acid transport, protein and DNA synthesis, and pancreatic hormone secretion. In the CNS, CCK induces hypothermia, analgesia, hyperglycemia, stimulation of pituitary hormone release, and a decrease in exploratory behavior. The CCK family of neuropeptides has been impHcated in anxiety and panic disorders, psychoses, satiety, and gastric acid and pancreatic enzyme secretions. 

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