Differential effects of progesterone and medroxyprogesterone on delay eyeblink conditioning in ovariectomized rats.

Ovarian hormones modulate acquisition processes involved in classical conditioning. Although progesterone has been indirectly implicated, its role in classical conditioning of the eyeblink response has not been directly investigated. We assessed the effects of daily dosing of progesterone or medroxyprogesterone (MPA), a non-metabolized synthetic progestin, upon the acquisition of a classically conditioned eyeblink response in ovariectomized (OVX) female rats.

Biochemical and anatomical substrates of depression and sickness behavior.

This paper reviews recent research on the contribution of the proinflammatory cytokine interleukin-1 (IL- 1) and the purine nucleoside adenosine in mediating behavioral depression and related symptoms of conservation-withdrawal in animal models of both major depression and illness. Activation of brain IL- 1 receptors appears to contribute to conservation withdrawal symptoms in animals treated with reserpine or lipopolysaccharide, suggesting a common underlying mechanism. Moreover, brain cytokine signaling is capable of recruiting adenosine signaling at adenosine A2A receptors, which directly mediate symptoms of behavioral depression.