Sex differences in dendritic atrophy of CA3 pyramidal neurons in response to chronic restraint stress
Section snippets
Animals
Sixteen female (50–56 days old) and 16 male (45–49 days old) 200 g Sprague–Dawley rats were purchased from Charles River. Animals were housed in same-sex pairs in wire-mesh hanging cages. Rats were given Purina rat chow and tap water ad libitum and maintained under a 12 h:12 h light/dark cycle (lights on at 7.00 a.m.). All animals were kept under these conditions for three weeks prior to the start of the experiment. Four days prior to the start of the restraint procedure, group mean weight for
In contrast to females, males showed dendritic atrophy in the apical tree in response to restraint stress
There were sex differences in the effects of repeated restraint stress on dendritic length, with males showing a decrease in the number and length of apical dendrites. Table 1 shows the number of branch points and dendritic length of control and stressed groups of male and female rats in both the apical and basal dendritic trees. Fig. 1 represents camera lucida drawings of a representative cell for each of the four groups of rats. Specifically, there was an interaction effect of condition by
Discussion
Consistent with previous results, male rats that underwent 21 days of restraint stress showed significant apical dendritic atrophy (a decrease in number of branch points and dendritic length) compared to non-stressed controls.21, 30Chronically restrained female rats, however, did not exhibit the severity of apical dendritic atrophy that was seen in stressed males. This result is consistent with a study in vervet monkeys, in which stressed males showed evidence of hippocampal pyramidal neuron
Conclusions
In addition to presenting the first comparison of morphological changes in the male and female rat hippocampus after repeated stress, this study also presents the first comparison of plasma corticosterone and CBG levels in male and female rats exposed to repeated stress. Females had higher basal and stress levels of both plasma corticosterone and CBG than males. They also had a more prolonged increase in plasma corticosterone levels in response to stress than males. Moreover, whereas plasma CBG
Acknowledgements
We thank Maryse Aubourg and Heather Cameron for their technical assistance. This research was supported by a NS07080 grant to BSM, and a postdoctoral fellowship from the Natural Sciences and Engineering Research Council of Canada to LAMG.
References (35)
- et al.
Stress response, adrenal steroid receptor levels, and corticosteroneicosteroid-binding globulin levels—a comparison between Sprague–Dawley, Fisher 344, and Lewis rats
Brain Res.
(1993) - et al.
Differential activation of adrenal steroid receptors in neural and immune tissues of Sprague–Dawley, Fisher 344, and Lewis rats
J. Neuroimmunol.
(1995) - et al.
Immune and neuroendocrine response to restraint in male and female rats
Psychoneuroendocrinology
(1993) - et al.
The dendritic morphology of pyramidal neurons in the rat hippocampal CA3 area. I. Cell types.
Brain Res.
(1989) Estrus-associated decrements in a water maze task are limited to acquisiton
Physiol. Behav.
(1995)- et al.
Gonadal hormone levels and spatial learning performance in the Morris water maze in male and female meadow voles Microtus pennsylvanicus
Horm. Behav.
(1995) - et al.
Gonadal steroid hormone receptors and sex differences in the hypothalamo-pituitary-adrenal axis
Horm. Behav.
(1994) - et al.
Sex differences in NMDA receptor mediated responses in rats
Brain Res.
(1993) Sex differences in “cognitive” regions of the rat brain
Psychoneuroendocrinology
(1991)- et al.
The dendritic morphology of pyramidal neurons in the rat hippocampal CA3 area. II. Effects of gender and the environment
Brain Res.
(1989)