Maybe know that the enteric nervous system can function completely independently of the rest of the cns. If the vagus nerve is severed the GI can still function. The system also responds to stimuli without brain intervention. For example as digestive material builds up in the intestines this stretches the intestine causing peristalsis to increase.
Great question. Hopefully someone else chimes in as I am not positive about this. When I think of the mesenteric nervous system I think of the reflexes in the GI tract that happen without the CNS what so ever. What comes to mind mainly with this are the stretch receptors through the tract. There are nerves that run through the GI tract in the mesenteric plexuses. To me this is what the enteric nervous system is. I think gastrin, secretin, GLP, CCK, etc are more of a endorcrine function as they go through the blood and thus require the rest of the body for their function unlike the independent reflexes.