Allopregnanolone produces hyperphagia by reducing neophobia without altering food palatability

The neurosteroid allopregnanolone may increase feeding by altering food palatability; however, it may also increase feeding by reducing anxiety (neophobia). Moreover, it is unclear whether this induced hyperphagia is selective to safe, palatable foods only. Male rats were injected with allopregnanolone 20 min prior to behavioral testing. The taste reactivity test was used to examine possible shifts in the palatability of a 0.3 M sucrose solution. A lickometer was used to monitor intake and licking of either a sucrose or sucrose-quinine solution. Sucrose palatability was not enhanced; however, allopregnanolone significantly increased sucrose intake and licking on Test Day 1 when the solution was novel, but not on Test Day 2 when the solution was familiar. Sucrose-quinine intake was not enhanced. Allopregnanolone-induced hyperphagia is not a result of altered sucrose palatability, but rather reflects a reduction in the neophobia elicited by a novel solution; an effect that further seems to be selective to safe, palatable foods.