Progestogens and estrogen influence impulsive burying and avoidant freezing behavior of naturally cycling and ovariectomized rats

Abstract

Steroid hormones, progesterone and estradiol, may influence approach and/or anxiety behavior. Female rats in behavioral estrus, have elevated levels of these steroid hormones and demonstrate more approach and less anxiety behavior than do diestrous rats. Ovariectomy obviates these cyclic variations and systemic progesterone and/or estrogen replacement can enhance approach and anti-anxiety behavior. However, the role of progesterone and/or estrogen in mediating impulsive, avoidant and/or fear behaviors requires further investigation. We hypothesized that if progesterone and/or estrogen influences impulsivity and/or fear then rats in behavioral estrus would demonstrate less impulsive behavior in a burying task and freezing behavior in a conditioned fear task than will diestrous rats. Ovariectomized rats administered progesterone and/or estrogen would show less impulsive burying and freezing behaviors than will vehicle-administered rats. Experiment 1: Naturally cycling rats were tested in marble burying or conditioned fear when they were in behavioral estrus or diestrus. Experiment 2: Ovariectomized rats were administered progesterone, estrogen or vehicle, then tested in marble burying or conditioned fear. Results of Experiment 1 show rats in behavioral estrus demonstrate less impulsive burying and less freezing behavior than diestrous rats. Results of Experiment 2 show administration of progesterone or both estrogen and progesterone decreases impulsive burying and each decrease freezing behavior compared to vehicle. Thus, progesterone and/or estrogen may mediate impulsive and/or avoidant behavior.

Dopamine D1 Receptor Activation Rescues Extinction Impairments in Low-Estrogen Female Rats and Induces Cortical Layer-Specific Activation Changes in Prefrontal–Amygdala Circuits

“…Progesterone levels fluctuate across the estrous cycle, undergoing a sharp peak shortly after that of estrogen, at the approximate beginning of the night of PRO (Staley and Scharfman, 2005). When administered either alone or with estradiol, progesterone given before extinction learning facilitates extinction retrieval in intact animals (Milad et al, 2009), and suppresses freezing in ovariectomized rats (Llaneza and Frye, 2009). In addition, there is evidence that progesterone can interact with dopaminergic systems (Frye and Sora, 2010;Yu and Liao, 2000), but how these interactions might influence extinction learning and retrieval has not been tested directly.…”

Influence of housing variables on the development of stress-sensitive behaviors in the rat

“…While tetrahydrofurandiols do not bind ER alpha, it has been shown to inuence ER levels in the brain and alter behavior by an unknown mechanism of action [23,49]. Notably, developmental exposure to estrogens (and progestins) has been shown to inuence anxiety-like behavior in male and female rodents, acting as an anxiolytic [50][51][52][53]. Likewise, through development, intake of phytoestrogens via diet has been shown to decrease anxiety-like behavior in Long-Evans rats in a similar direction as shown in this manuscript [54].…”

Sex differences in animal models of psychiatric disorders

“…Thirty percent of female rats bury more marbles in dioestrous, in comparison with prooestrous, and this is attenuated by acute treatment with the antidepressants fluoxetine, nomifensine and the anxiolytic diazepam (Schneider and Popik, 2007). Accordingly, female rats spend more time burying in dioestrous than in prooestrous (Llaneza and Frye, 2009). However, others have found that in this test, female rats in prooestrous are more sensitive to diazepam, than male and female rats in dioestrous (Fernandez-Guasti and Picazo, 1990).…”