Homer Simpson and the gang hit 5oo

There are television shows and then there's The Simpsons. The animated comedy, which celebrates its 500th episode in the US on Sunday (the episode will air on Sky One in May) – occupies its own space in television history. It is America's longest-running show, currently in its 23rd season and, despite recent contract disputes, shows no sign of nearing its end.

"I think we're going to keel over doing this show," admits its creator Matt Groening. "We have a great group of people working on it who want to continue doing it. If we ran out of ideas – and I don't imagine that happening – we would probably give up but we're having too good a time."

Groening remains bullish over suggestions that The Simpsons, which was spun off into a hit movie in 2007, has suffered any loss of form.

"The Simpsons is basically a forum for different kinds of comedy," says Groening. "We've tried different jokes and different styles and we parody different kinds of animation styles and our range of references go from truly obscure literary references to the most dumb, broad comedy that you can imagine."

It's certainly the case that the show continues to attract all manner of celebrities keen to have a go at being yellow. The new series features cameos from Lady Gaga and Jeremy Irons while the 500th episode itself has a voiceover from the (increasingly rather less) secretive WikiLeaks founder Julian Assange.

"The Simpsons go off the grid to this very rugged place where they meet Assange, who's sort of their new Ned Flanders in that he lives next door," says Al Jean, co-producer. "The similarities end there..."

The rest of the episode "addresses what it would be like to have The Simpsons as your neighbours for 500 episodes", says Jean, who attributes the show's long lasting success to the fact that "it's evergreen... and we really care about it, we work really hard".

As to how long the show will continue to run the two men remain coy. "I think everyone who works on it has a secret final episode in mind," says Groening. "We've talked about it but I don't think we've come to any conclusion that we're all happy with."

'The Simpsons' is on Sky 1 HD and Sky 1, weekdays at 6.30pm. The 500th episode will air in May