The effects of chronic restraint on the morphology of ventral CA1 neurons in female Long Evans rats.

Women are more likely than men to develop psychopathology as a result of stress, but there is little research regarding the effects of a stressful condition and its treatment in female non-human animals, perhaps because of inherent hormonal activity. Recent studies have demonstrated that there are structural and functional differences between the dorsal and ventral hippocampus, but the effects of stress on the morphology of CA1 and CA3 neurons have been studied primarily in the dorsal hippocampus. This study assessed the effects of stress induced by restricted movement on the morphology of ventral hippocampal CA1 neurons in male and female rats. Male and female Long Evans (LE) rats were subjected to restraint stress for 6 h every day for 25 days. One group of rats was used to study the dendritic morphology of CA1 ventral hippocampal neurons using the Golgi-Cox stain. A second group of rats was used to analyze learning and memory using the Morris water maze. Stressed female rats exhibited a decrease in the density of basilar dendritic spines, an increase in the number of apical dendritic intersections and deficits in spatial memory. There were no apparent effects of stress on male rats. Our data support previous findings of a dimorphic response to chronic stress and indicate that the ventral hippocampus is not particularly susceptible to the effects of stress.