Regan has not started a game for Rovers since the 6-1 defeat at Walsall last month and the arrival of right-back Danny Senda has seen the 30-year-old fall further down the pecking order at the Memorial Stadium.
Regan has twice played under current Notts boss Paul Ince - at Macclesfield and MK Dons.
He will go straight into the Notts squad for the home game against Charlton on Friday night.
Source: PA
Source: PA