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.

• CA1 neurons
• female and male rats
• long evans rats
• stress
• spatial learning and memory
• ventral hippocampus

Acknowledgements

The authors wish to thank Dr. Carlos Escamilla for his help with the animal care and Dr. Daniel I. Limón for his help with the Morris water maze. AMR and DABD performed the morphologic analyses, ALM and HDLLT applied the water maze test and ABSG conducted the data analysis and wrote the paper.

Declaration of interest

There are no conflicts of interest among the authors. This work was supported by F-PROMEP-21/Rev 05 SEP-23-003-A and CA-PIFI 2009. Support was provided to AB Silva-Gómez. None of the funding institutions had any further role in the study design, collection of data, analyses and interpretation of data, writing of the report or decision to submit the paper for publication. Elsevier Language Editing Services was hired for editing the English language text. All authors have no conflicts of interest.