Hustler magazine publisher Larry Flynt rolled into federal court here today in a gold-plated wheelchair and did his best, as did his psychiatrist, to convince a jury in a $45 million libel trial that he never intended to harm Moral Majority leader Jerry Falwell by publishing a controversial ad parody.

Flynt, dressed in a three-piece suit, also told the jury that his claim in a videotaped deposition that he did intend to harm Falwell should be disregarded for medical reasons.

"I feel fine today," Flynt said on the stand, "but at the time of the deposition I was in extreme pain. I had a terrible bed sore . . . and I'd been in solitary confinement for several months, handcuffed to my bed most of the time."

Flynt is being sued by Falwell over a liquor advertisement parody that purported to quote Falwell saying he frequently got "sloshed" before preaching and that his first sexual experience was with his mother.

Flynt and his lawyers have contended that the parody, which included a disclaimer at the bottom, was an obvious spoof that no reader could have mistaken as truth. Falwell disagreed and is seeking punitive and compensatory damages for libel, invasion of privacy and intentional infliction of mental harm.

Falwell has retained New York lawyer Norman Roy Grutman, who counts among his clients Penthouse magazine publisher Robert Guccione. Grutman successfully represented Guccione when Falwell sued Penthouse for libel more than a year ago.

Flynt and Grutman are old adversaries, and today their battle of wits was both cutting and entertaining. Grutman tried unsuccessfully to goad Flynt into losing his temper and Flynt needled Grutman by referring to him several times as Norman.

"He did that on purpose," Grutman said during a recess. "He knows I don't like to be called by my first name."

It was Grutman who conducted the controversial videotaped deposition six months ago at a federal prison in North Carolina. In that 3 1/2-hour tape, a bearded and angry Flynt, paralyzed from the waist down since being shot in 1978, lies on his back on a hospital gurney.

Grutman has characterized the deposition as proof that Flynt did not intend the ad as a parody, has long held malice toward Falwell and added the disclaimer only to satisfy the magazine's lawyers.

He also has stated that Flynt's claim of mental illness is calculated to defuse the damaging statements of the deposition.

"I notice not a single obscenity this morning," Grutman said of Flynt's subdued courtroom demeanor. "Is this Larry Flynt the real Larry Flynt or was the real Larry Flynt the one we saw on the TV screen?"

Flynt answered, "I'm more myself than I was then . . . . Norman, you're trying to make it sound like I was okay. I was not okay. I had problems. Anyone who knows me knows that I had problems."

Saul Niedorf, a California psychiatrist who has been treating Flynt for more than a year, went further. Niedorf testified today that Flynt suffers from a chronic manic-depressive disorder. He said that the tape, in which Flynt claims among other things to have the entire FBI working for him and to have proof of Falwell's drunkenness and incestuous relationships, should be viewed as the ravings of a sick man.

Niedorf said that Flynt's numerous and outrageous confrontations with judges are the classic manifestations of the manic phase, in which the individual has little or no control over himself and often says and does things not in his own best interest.

"He's a wonderful storyteller, but he's a very ill man," Niedorf said after court adjourned for the day. "And he was crazier than a loon during that deposition."

Flynt has been receiving drug treatment, including the antidepressant Lithium, and is currently in good shape, according to the doctor.

Falwell's lawyers have rested their case.

After the defense calls a few remaining witnesses tomorrow morning, the eight-woman, four-man jury will hear closing arguments and is expected to begin its deliberations late in the day.