Brain cholecystokinin, action

The regulation of food intake in humans is complex. In addition to genetic and cultural influences, it involves the action of leptin, insulin, ghrelin, PYY, cholecystokinin, and amylin. Most of these molecules act by signaling to the brain. 

Substances with a neuromodulatory effect on brain neurotransmitters by direct actions of specific receptors that modify the actions of the transmitters listed include prostaglandins, adenosine, enkephalins, substance P, cholecystokinin, endorphins, endogenous benzodiazepine receptor ligands, and possibly histamine. CNS, central nervous system. NMDA, N-methyl-D-aspartate. Strych, strychnine. 

So far we have discussed the effect of CCK peptides on serotonin brain concentrations. Some evidence also exist on the action of serotonin on the CCK system. Raiteri and colleagues (1993a) looked at the effects of serotonin on the release of cholecystokinin-like immunoreactivity (CCK-LI) in synaptosomes prepared from rat cerebral cortex and nucleus accumbens. In both areas, serotonin increased the calcium-dependent depolarization-evoked CCK-LI release in a dose-related fashion. This effect was antag-... 

Dodd J, Kelly JS The actions of cholecystokinin and related peptides on pyramidal neurones of the mammalian hippocampus. Brain Res 205 337-350, 1981... 

Kaneyuki T, Morimasa T, Shohmori T Action of peripherally administered cholecystokinin on monoaminergic and GABAergic neurons in the rat brain. Acta Med Okayama 43 153-159, 1989... 

Cholecystokinin (CCK) The tetrapeptide CCK causes more panic attacks when infused into patients with panic disorder than it does in normal volunteers, which suggests increased sensitivity of the brain type of CCK receptor, known as CCK-B. Unfortunately, in early investigations CCK-B antagonists did not appear to be effective for panic disorder. Nevertheless, agents with novel pharmacological mechanisms of action are sometimes evaluated for their potential antipanic actions by testing whether they can block CCK-induced panic attacks. 

Several amino-acids are important neurotransmitters in the c.n.s. Glutamic and aspartic acids seem to be excitatory transmitters in the entire brain. y-Aminobutyric acid (GABA) and glycine are important inhibitory transmitters, the former in supraspinal interneurons and the latter at spinal interneurons (Curtis and Johnston, 1970). Of the polypeptide neurotransmitters, the most studied have been the endorphins and enkephalins (see Section 12.8), Substance P (an undecapeptide that helps transmit the sense of pain (von Euler and Pernow, 1977, somatostatin, and gastrin, and cholecystokinin whose action in the gut has been well researched. For more on GABA, see Section 12.7. 

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