His other friends like Shikamaru would use his intelligence to figure out what Danzo has done and where Naruto is being held. He would then rally the rest of their friends, including Choji and Ino, to mount a rescue mission. They would all be horrified at what has happened to Naruto and would be determined to bring him back safely and ensure that justice is served against Danzo.
Sakura might be extremely angry and feel guilty for not being able to protect Naruto. She could immediately start planning ways to rescue him and make Danzo pay for what he's done.
Sasuke would likely be enraged. Given his own experiences with the village's dark side, he would see this as another example of the village's corruption. He might go on a rampage to find Naruto and take revenge on Danzo, perhaps even allying with some unexpected forces in the process. His loyalty to Naruto would drive him to extreme actions.
Sasuke would be furious. He already has a strong sense of justice and loyalty to Naruto. He'd likely immediately start looking for Naruto, using his Sharingan to track any possible leads. He might even go against the village rules if he thought the village was involved in Naruto's kidnapping.
Well, Naruto's friends would be in an uproar. Iruka, who has always been like a father figure to Naruto, would be heartbroken and would not rest until he knew Naruto was safe. The other Konoha ninja would also be affected. Neji, despite his initial coldness towards Naruto, has come to respect him. He would see Orochimaru's actions as a threat to the village and to his friend. Tenten would offer her weapon - related skills to help in any rescue attempt. And Hinata, who has deep feelings for Naruto, would be extremely distraught. She might even try to take on Orochimaru herself in a desperate attempt to save Naruto, regardless of the danger to her own life.
Naruto could also become more vengeful. If he survived the experiments, he would likely be angry at Danzo for what he had done. This could lead to a darker side of Naruto emerging, where he is focused on getting revenge rather than his original goal of becoming Hokage and being accepted by the village. He might be more willing to use force and be less forgiving.
At first, Naruto would probably be excited. He's always eager to get stronger, so he might see this as an opportunity. He'd trust Tsunade because she's the Hokage and a respected medical ninja. But if the experiments got too painful or started to seem strange, he'd start to question things. He might try to talk to Tsunade about it, but in his Naruto - like way, still be respectful.
He would probably be very angry. Naruto has always been a free - spirited person, and being experimented on against his will would be a huge violation of his rights. He might initially try to resist physically, but as the situation gets more complex, he could start to plot his escape and revenge.
He probably resists. Naruto has always been a fighter. He would not just sit there and let them experiment on him without a fight. He might use his basic ninja skills like substitution jutsu to try and escape the experimenters.
Sakura, being the kind - hearted and practical one, would immediately start giving Naruto advice on how to keep his braces clean. She might also tell him about the foods he should avoid so that the braces don't get damaged. Sasuke, on the other hand, would be his usual aloof self. However, if any other village kids were to make fun of Naruto because of the braces, Sasuke might subtly step in and intimidate them. Shikamaru would likely grumble about Naruto's new look adding to the chaos in their group. But deep down, he would understand that it's just another thing that makes Naruto unique. Kiba and Akamaru would initially find it funny. Kiba might even joke that Naruto's braces look like some strange ninja weapon. But as time goes on, they would all get used to it and it would just become a normal part of Naruto.
One possible plot could be Naruto developing new and unexpected powers as a result of the experiments. Maybe he has to struggle to control these new abilities while also dealing with his feelings of betrayal towards the village that allowed Danzo to do this to him.
Sakura would probably be really concerned. She has known Naruto for a long time and would want to make sure he's okay. She might try to talk to him and get him to open up about his feelings.
His friends' reactions could vary greatly. For example, Choji might be a bit scared at first, seeing Naruto as a wolf. But once he realizes it's still Naruto, he would offer him food. Ino could use her mind - transfer jutsu to communicate with Naruto in his wolf form. And Hinata would be very concerned and would stay close to Naruto, trying to protect him from any harm that might come his way because of his new form.