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

Abstract

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.

Adjunct treatment with ketamine enhances the therapeutic effects of extinction learning after chronic unpredictable stress

“…Our data also do not exclude the possibility that lower doses of ketamine may enhance the responsivity of the mPFC from another input, such as the vHipp. In females, but not males, chronic stress affects dendritic morphology of vHipp neurons, ( Morales Rico et al, 2015 ). Thus, the vHipp is sexually dimorphic in the context of stress and response to treatment ( Galea et al, 1997 ; Shors et al, 2001 ).…”

Ventral hippocampus, Stress and Psychopathology: Translational implications

“…Morales Rico et al [14] subjected male and female Long Evans rats to chronic restraint stress. Stressed female rats exhibited a decrease in the density of basilar dendritic spines and an increase in the num ber of apical dendritic intersections in VH accompa nied by deficits in spatial memory.…”

Dendritic Spines in Depression: What We Learned from Animal Models

“…Similar to acute stress, the same CRS regimen causes a decrease in spine density in the apical dendrites of hippocampal CA1 pyramidal neurons in male rat and male mouse [ 40 , 43 , 46 , 48 ] but causes an increase in spine density in the same region in female rats [ 37 , 38 , 42 ]. One recent study shows that CRS decreases spine density in basal dendrites, while it increases apical dendritic arbors in the CA1 pyramidal neurons of the ventral hippocampus in female but not in male rats [ 47 ]. In contrast to female rats, female mice show a decrease in spine density in CA1 pyramidal after exposure to same 21-day CRS [ 45 ].…”