EnteroMedics, a St. Paul, Minn., developer of obesity-treatment implants, filed to raise up to $86.25 million in an IPO. Its S-1 filing with the SEC is here.

The company is developing a neuromodulation implant called VBLOC that is designed to intermittently disrupt signals sent along the vagus nerve, which regulates many functions of the stomach, intestines and pancreas. Ideally, the implanted device will limit stomach expansion, reduce the frequency and strength of stomach contractions, and induce a sense of fullness in patients. The company envisions the device as a safer and less invasive obesity treatment than drug therapy or interventions such as bariatric, or stomach-reduction, surgery.

EnteroMedics plans to test VBLOC in a large 220-patient trial starting in the third quarter. This trial will actually be placebo controlled, which in this case means that roughly one-third of the patients will have the device implanted, but never turned on. That sort of trial design should produce more reliable data than most device trials, which often don’t employ placebo comparisons. If all goes well, the company believes it may bring VBLOC to the market in 2010.

The company has so far raised approximately $64 million in venture funding, according to VentureWire (subscription required). Major shareholders include MPM Capital, Bay City Capital, Aberdare Ventures, InterWest Partners and Onset Ventures.