In an aqueous solution, the reduction of the metal center in permanganate ions ($MnO_4^-$) varies depending on the medium :

Acidic Medium : Permanganate acts as a strong oxidizing agent. The reaction can be represented as :

$$8H^+ + 5e^- + MnO_4^- \to Mn^{2+} + 4H_2O$$

This indicates that 5 electrons are involved in the reduction process in an acidic medium.

Neutral Medium : Permanganate acts as a moderate oxidizing agent. The reaction in a neutral medium is :

$$2H_2O + 3e^- + MnO_4^- \to MnO_2 + 4OH^-$$

Here, 3 electrons are involved in the reduction process in a neutral medium.

Alkaline Medium : In alkaline conditions, the reaction is similar to that in a neutral medium :

$$2H_2O + 3e^- + MnO_4^- \to MnO_2 + 4OH^-$$

Again, 3 electrons are involved in the reduction process in an alkaline medium.