Of the stages, females that were trained during proestrus (stressed 24 hours earlier in di estrus) were

most impaired by stressor exposure.11 Since this stage is associated with elevated levels of estrogen, the hormone is again implicated in these stress effects on conditioning. Figure 3. Contribution of ovarian hormones to the stress effect on learning in females. A. Females that were ovariectomized (OVX) prior to stressor exposure and training were not impaired by stress and exhibited a similar response to those exposed to a sham surgery. … Recall that females under normal unstressed conditions Inhibitors,research,lifescience,medical learn faster in proestrus than in other stages. How might estrogen contribute to both enhanced learning under unstressed conditions and impaired learning after stress? It may be BTB06584? useful to consider the effect of stress on

learning from a slightly different perspective in which stress does not impair conditioning directly, but rather prevents the enhancement, that normally occurs when estrogen levels Inhibitors,research,lifescience,medical are elevated. Neuroanatomical correlates of stress and sex differences in learning These opposite effects of stress in males and females pose Inhibitors,research,lifescience,medical some interesting questions, one being whether there is a neuronal or anatomical substrate that can account for these opposite responses to stress. .First, we considered a potential role for dendritic spines, tiny protrusions on many dendrites Inhibitors,research,lifescience,medical in the brain, which are a source of excitatory input.39 Because they enable connections and associations to be made between adjacent neurons, it

has been hypothesized that they are involved in the formation of associative memories. Despite the pervasiveness of the hypothesis in the literature, there are minimal data in support of this. In fact, the most. potent modulator of dendritic spines so far established is estrogen. Acute Inhibitors,research,lifescience,medical exposure to estradiol enhances spine density in the selleckchem hippocampus of ovariectomized females; moreover, females in proestrus have a greater spine density than females in other stages.40,41 The effect of estrus on spine density is rapid and dramatic, varying as much as 30% over the 5-day cycle. Recently, we compared the changes in spine density across the estrous cycle in females with that, Anacetrapib of males. As shown previously,42 females in proestrus had a greater density of dendritic spines on apical dendrites in area. CA1 of the hippocampus. As shown in Figure 4, we also observed that females in proestrus have a greater density of spines in the hippocampus than do males.43 As discussed, it has long been assumed that dendritic spines participate in learning processes. So docs this change in spine density across the estrous cycle and between the sexes relate to learning ability? At.