GA flight instructor on training flight with student reported a ground conflict on the takeoff roll with another aircraft taking off from the opposite direction.

Narrative

I was PIC in Aircraft X with a student holding short of Runway 23 at GIF. Aircraft Y departed in front of us; and three other aircraft were in the traffic pattern landing and taking off Runway 23. After departing aircraft reach roughly 400 feet of altitude my student called on UNICOM (123.05) 'Winter haven Traffic; Aircraft X departing XX left closed traffic' we entered the protected area and began our departure. Upon reaching rotation speed and beginning rotation I noticed an aircraft at roughly 25-50 feet AGL departing straight at us. I immediately took controls of the aircraft and aborted the takeoff to avoid a head on collision. I keyed into UNICOM and asked the pilot of the aircraft what he was doing and what he was thinking and advised the pilot that he just departed directing into us. He advised me the winds were calm and calm wind runway at GIF was 05 not 23 and that he made the call that he was departing. Neither I nor my student heard his departure call nor did any other aircraft in the pattern.