Ashton Kutcher finally touched down in LA -- two days after Demi Moore was rushed to the hospital -- looking far more concerned than he did earlier this week in Brazil.

Ashton was spotted partying hard at a Bruno Mars concert -- the day after Demi was hospitalized when she fell into convulsions at home. She was taken by ambulance to a nearby hospital ... where she's been getting treatment for substance abuse.

Demi announced her plans to divorce Ashton back in November.

Ashton Kutcher's fist pumping in Brazil, Demi Moore's hospitalized after getting high like teenagers do -- and TMZ staffers are doing PSAs on the dangers of whip-its! The whole world's upside down. 

Just one night after Demi Moore was rushed to the hospital for inhaling too much nitrous oxide -- Ashton Kutcher hit up a Bruno Mars concert in Brazil ... where he fist-pumped his brains out.

The video was shot the same night Ashton dropped by a nightclub in Sao Paulo with a mystery female companion in a red shirt -- the same girl is standing beside him at the Bruno Mars concert.

As we previously reported, Ashton gave a Brazilian photog the cold shoulder when asked if Demi was okay -- giving no answer.

Famous Concertgoers

Ashton Kutcher had no answer when asked if Demi Moore was okay following her nitrous oxide-induced medical emergency -- hopping wordlessly into a car beside a blonde mystery woman Tuesday night.

The video was shot as the actor was leaving a nightclub in Sao Paulo, Brazil -- an agency photog asks, "Is Demi okay?" ... and Ashton keeps mum, piling into an idling vehicle with two acquaintances, one female.

Ashton has yet to speak out on Demi's condition. The two split in November.

Demi Moore was rushed to the hospital Monday night ... and we're told the issue is substance abuse.

Law enforcement tells us a 911 call was placed at 10:45 PM Monday night. Paramedics responded to Demi's L.A. home and after assessing her for a half hour, she was transported to a local hospital.

Sources tell us she is being placed in a facility to "seek further professional assistance." Our sources say the treatment is for substance abuse.

Demi's rep tells TMZ, "Because of the stresses in her life right now, Demi has chosen to seek professional assistance to treat her exhaustion and improve her overall health. She looks forward to getting well and is grateful for the support of her family and friends." 

Ashton Kutcher's style wasn't cramped at all in the wake of Demi Moore's health crisis -- he was partying Tuesday in Sao Paulo, Brazil at a Bruno Mars concert and a nightclub.

We put a call in yesterday to Ashton's rep for comment on Demi's situation, but so far ... radio silence.

Sara Leal -- the 22-year-old blonde who allegedly slept with Ashton Kutcher this summer -- insists she isn't responsible for the actor's crumbling marriage to Demi Moore ... telling TMZ, she was just a "bump in the road."

Sara tells us, Ashton and Demi were having problems long before she came along -- but was she the straw that broke the camel's back?

Less than two weeks before Demi Moore announced she would divorce Ashton Kutcher, he threw a Hail Mary to save the marriage ... in the form of a lavish, eco-friendly gift. 

According to our sources, Ashton contacted a high-end car company, to buy a new set of wheels for Demi's birthday. We're told Ashton picked out a 2012 Lexus LS 600h L -- and paid North of $100,000.


Our sources say Ashton wanted a quick deal -- bagging the luxury hybrid on November 9, just two days before Demi's birthday.

If it was meant to win back Demi ... clearly it didn't work. We don't know if Demi accepted the vehicle or if Ashton was able to give it back to the car company.

On the upside -- 22 mpg!

Only in Hollywood can someone who slept with a married man claim they feel "lied to" -- but that's what Brittney Jones, Ashton Kutcher's alleged mistress, told our photog yesterday.

As TMZ first reported, Jones -- whose alleged tryst with Kutcher in 2010 was heavily denied by his camp -- says she felt vindicated when Demi Moore finally pulled the plug on her marriage to Ashton.

Jones said she hasn't spoken to Ashton lately but she wishes him and Demi the best.

How comforting.

Ashton Kutcher's alleged mistress -- the FIRST alleged mistress -- claims she feels "vindicated" by Demi Moore's divorce statement ... telling TMZ she hopes people will finally believe her story about sleeping with Ashton.

TMZ spoke with Brittney Jones -- who claimed she got busy with Kutcher in 2010 after meeting the guy at a bowling alley. Jones' credibility was called into question when she capitalized on her sudden fame by releasing a sex tape .... which did NOT feature Ashton.

Ashton's lawyer released a statement at the time Brittney was in the headlines, insinuating her story was a lie ... but not entirely denying

Now, Jones tells TMZ ... "Although divorce is often sad I do feel somewhat vindicated."

She adds, "For so long people have thought that I was dishonest or just making up my passionate nights with Ashton, when in fact I was being used."

"Ashton told me that both he and Demi had an 'open relationship' and that he was not in fact cheating.  Now I can tell all the facts about how Ashton really was, and hopefully people will believe my side of the story."

Still, Jones says, "I feel for Demi very much and wish her nothing but the best during this hard time."

Demi Moore will divorce Ashton Kutcher, her husband of 6 years ... and she's strongly suggesting it's because of the cheating scandal.

The 49-year-old Moore says she's ending her marriage "with great sadness and a heavy heart."

Demi says, "as a woman, a mother and a wife, there are certain values and vows that I hold sacred, and it is in this spirit that I have chosen to move forward with my life."

Ashton just tweeted, "I will forever cherish the time I spent with Demi. Marriage is one of the most difficult things in the world and unfortunately sometimes they fail" -- though it's unclear if this message was approved by his Twitter team.

Demi and Ashton made headlines in September after a 22-year-old woman named Sara Leal claimed she had unprotected sex with him in San Diego.

Leal claimed Ashton told her he was "separated" from Demi at the time of the alleged affair.