Not surprisingly, given the sluggish ratings of the program and the lack of critical support, Cybill Shepherd is leaving the syndicated daytime talk show "Men Are From Mars, Women Are From Venus," according to Columbia TriStar TV program and production president Russ Krasnoff. Speaking to TV reporters at a gathering in Las Vegas, Krasnoff said that the former "Moonlighting" star, 50, will be replaced on "Mars" by a panel of five men and women. They are MTV "Loveline" cohost Dr. Drew Pinsky, comedian Rondell Sheridan, Los Angeles-based talk show host Christina Ferrare, Bo Griffin from Miami and Sam Phillips, a model. The switch, Krasnoff said, was effected because "we found that we just weren't properly servicing the Mars/Venus brand by not providing both sensibilities of men and women." Shepherd had been with the show since its premiere last September. No exact date for her departure has been given.