In what one literary agent calls the oddest "article that's appeared in a national magazine," New York Magazine this week offered its readers Christina Paolozzi Bellin's very intimate paean to rock 'n' and the disco world.

If you didn't know Bellin's father was an Italian count, that her mother was a United Fruit heiress, that as a young woman Bellin was a "trailblazer among the rich clique of the international thrills-seeker set," that her admission of open marriage several years ago led to depression, that a face lift and an 18-year-old Israeli boy who took her dancing helped her rediscover a love of life, well, you'd know after you read "Rock Keeps You Young."

The article by Bellin, who is 38 and married to a Manhattan plastic surgeon, is a bizarre first-person piece that raised eyebrows in New York's publishing circles, if only because Bellin's writing appears not to have been edited.

Her father was "the most attractive swinger in Roma." Her sister went to "the finest girls' boarding school in the U.S.A." The co-owner of a New York disco is "America's leading rock promoter," Bellin writes twice, adding in the second reference that he's opened "the ultimate discotheque." One paragraph begins, "I was sunbathing nude in front of my summer East Hampton house . . ."

"We didn't touch a word," says New York magazine editor John Berendt. "It's a remarkable social document, very revealing, a commentary on the world of disco, pop and beautiful people."

Berendt says Bellin "signaled the beginning of what came to be known as pop," when, as a young model, she shocked the fashion world by appearing topless in Harper's Bazaar. Perhaps struck by the tone of the writing ("In Europe we knew that you could only have fun with your inferiors"), and editor at New York called Bellin and offered her $350 for the piece.

But Bellin says she hadn't intended her writing to be a magazine article. Instead, she had meant what eventually appeared under her byline to be a request that she be assigned to write a piece on rock 'n' roll. Christina Paolozzi Bellin, after a career as model, actress, socialite and mother, decided she wanted to be a journalist.

Two years ago Bellin began taking journalism courses at Columbia Unversity. "Every one of my teachers said, 'Christina, you have no punctuation, no structure, no knowledge of composition,' So I said, 'You're right. I'm a high school dropout,'" recalls Bellin.

Then she began researching an article on rock 'n' roll stars but could get no interviews because, she suspects, "everyone thinks I'm a personality, not a journalist." At the suggestion of a friend, she wrote a few pages about why she ought to write the music piece, based on her own life-long love of rock music.

"I sat cross-legged on the floor with my secretary with all these newspaper clippings of the past 25 years and I said, 'Oh, look at this, oh, fantastic, I remember this,' and we put it all down and that's how the article got writen. It took 22 minutes."

And that was what New York saw fit to print. Surprised by a call from a New York editor offering to purchase and print her rock 'n' roll reminiscence, Bellin says, "I'd be an absolute fool if an editor says 'I'm going to print it,' and I didn't expose myself like that. The most important part is the fact that it said 'Christina has turned to journalism after a varied career.' I would have been a fool to stop that article."

Bellin thinks the prose is "childish."

"But," says Bellin, "I noticed it contacted people emotionally. There's a quote that people would rather have one good, soul-satisfying emotion than a dozen facts."

Old lovers called her, she says, to renew friendships. She was grilled by New York talk-show host Stanley Siegal, who tried to get her to discuss lovers. (Bellin concludes the piece with a rhapsody to an 18-year-old Israeli boy who "is exquisitely handsome, sexy, with a beautiful voice" whose visit with her "turned out to be the most exciting six months of my life. I was old enough to understand what was happening and to enjoy it.") But aware of the fact that her husband works in a Catholic hospital, Bellin plays coy about affairs: "I did have an open marriage," she says carefully. "Now if someone wants to flirt with me, they just have to take a chance - maybe I still have love in me, maybe I don't."

Her husband of 14 years, Dr. Howard Bellin, says he's very proud of his wife's first article.

"Five years ago she had become depressed, a housewife who let her face and body go and suddenly she became interested in life again. Do I dance? You betch! It's fabulous exercise. Dancing, karate and lovemaking are three incredible things I do and they keep me in total shape and I haven't had any plastic surgery."

(Bellin's face lift was performed by a friend of her husband, a natural consequence of a "tremendous movement afoot to stay healthy and look healthy," remarks her husband).

Bellin is off to London next week for couple of months, and she happily notes that Studio 54 is opening a disco there.

"It's called 'disco craze." What happens to a city like New York is that there are a lot creative people, and all the creative people need about 10,000 backup people from taxi drivers to doormen. By the time a creative person stops creating, you look at the clock and it's 9 p.m. You've missed the cocktail parties, the dinner party, your husband has called to say his office is full of patients.

"So the first thing I do," says Bellin, "is go look in on my two children I find them happy, their homework done, lying in bed watching TV. I don't feel like going to a sit-down party so the nicest thing to do is go with a friend - a girl or boy or anything - and go dancing. You pay your $10 and you get all the cricks out of your neck. Discos, you see, answer a very great need in society because all of us work very, very hard and by the end of the day all of us don't want to sit down and watch TV."

Notes editor Berendt: "It was an honest statement by a woman very much involved in this crazy scene."