A BIG HAND FOR THE LITTLE THEATER

Amid the spate of youth-oriented movies, actresses who used to be considered relatively young are starting to feel positively middle-aged.

Particularly when, like Brooke Adams, who is 35, they’ve been acting since childhood (she used to walk on in her father’s summer theater when she was 6).

But, instead of sitting around griping about the paucity of roles, Adams is taking the rest of the summer to help run a small theater in Upstate New York. And the first play to be staged is by her sister Lynne, “Over Mother’s Dead Body.”

“Theater is in such a bad state right now that we decided we should do something about it,” said Adams the other day. “So Lynne and two friends of ours raised sufficient funds in New York to start this theater in Lexington.

“We’re all going to live up there--in a converted inn nearby. We’ve hired a resident cook, and there’s plenty of room for all the actors.”

Although best known for her movies--among them “Days of Heaven” and the remake of “Invasion of the Body Snatchers”--Adams has done a lot of theater. She was in the original Off-Broadway production of “Key Exchange” and, for a month in 1981, repeated her role in a production at the Westwood Playhouse.

“That was a most depressing experience,” she said, “not like being in the theater at all. Nobody ever came backstage; nobody went out for drinks afterward. It was awful.”

But she loved the play and jumped at the chance to be in the movie (opening next week).

“I never thought it would translate to the screen,” she said, “but it has. And I’m happy with it.” Directed by Barnet Kellman, “Key Exchange” also features Ben Masters from the original production.

Adams last month joined a delegation of women on a visit to El Salvador and Nicaragua. Being fluent in Spanish (she lived in Spain for almost four years), she did much of the translating.

The itinerary in El Salvador included a visit to a women’s prison. When it was over, a prisoner came up to her and said, “You know, you look so much like the actress who was in ‘Lace’ on television.”

“I could hardly believe it,” said Adams, who was in both “Lace” and “Lace II.” “It turned out the prisoners had watched it while on a hunger strike. Talk about the power of TV . . . .”

NOT WORRIED: Undismayed by the cool initial reviews of “Summer Rental,” which he directed, Carl Reiner took off for New York this week to watch his favorite singer perform at the Greene Street Cafe. She is Estelle Reiner, his wife of 42 years.

“She’s a terrific jazz singer,” said Reiner before he left. “She’s always been good, but it’s only lately she’s had the courage to go up on stage and perform.”

In New York, Reiner will do some promotion for his movie, then take off for the South of France, where he has a summer rental--near Mougins.

“We love it there,” he said, “and I speak enough French to get by. In fact, when I was in France a while back promoting ‘Dead Men Don’t Wear Plaid,’ I answered questions at the press reception in French. I don’t find the French unfriendly--if you make an effort. And I do. I literally force cabdrivers to like me.”

A LIGHTER ROLE: Raul Julia, who stars with William Hurt and Sonia Braga in Hector Babenco’s “Kiss of the Spider Woman” (opening Aug. 23), shed 30 pounds to play his role of a political prisoner.

“I had no choice,” he says. “There are no fat revolutionaries.”