Inactivation of Basolateral Amygdala Prevents Stress-Induced Astroglial Loss in the Prefrontal Cortex
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Repeated stress causes cognitive decline and decreases the expression of glial fibrillary acidic protein (GFAP)+ astroglial cells in the prefrontal cortex (PFC). The stress-induced alterations in astroglial density and morphology might significantly contribute to cognitive impairments. Apart from PFC, a key region involved in modulation of repercussions of stress is basolateral amygdala (BLA), which undergoes hypertrophy following chronic immobilization stress (CIS) and has intense reciprocal connections to the PFC. Interestingly, inactivation of BLA precludes stress-induced learning deficits. However, the modulatory role of BLA on CIS-induced alterations in GFAP+ astroglial density and associated learning deficits are presently unknown. Accordingly, we present two sets of experiments evaluating the effects of BLA inactivation either permanently or temporarily on CIS-induced changes in learning and astroglial expression in the PFC. CIS causes impairment in novel object recognition memory and astroglial loss in the PFC. In experiment I, we permanently inactivated the BLA by ibotenate lesion prior to CIS and observed a significant improvement in learning. Surprisingly, BLA lesion also prevented the stress-induced astroglial loss in the PFC. Furthermore, in the experiment II, we analyzed whether the effects of permanent inactivation could be mirrored by the temporary blockage of BLA specifically during stress. Interestingly, temporary inactivation of BLA mimics the effects of lesion. There was a notable prevention of learning impairment and astroglial loss in the PFC following BLA inactivation during stress. The present study emphasizes that stress-induced astroglial loss might contribute to cognitive deficits and modulation of BLA activity might be a viable strategy for management of stress-related PFC dysfunctions.
KeywordsChronic stress Inactivation of basolateral amygdala Prefrontal cortex Astroglial plasticity Cognitive deficits
Anterior cingulate cortex
Glial fibrillary acidic protein
Chronic immobilization stress
Novel object recognition
- HPA axis
Hypothalamic pituitary adrenal axis
Sunil Jamuna Tripathi was supported by a Senior Research Fellowship (File No. 09/490(0095)/2014-EMR-I) from the Council of Scientific and Industrial Research (CSIR), New Delhi, India. Suwarna Chakraborty was supported by a research fellowship (NIMH: A&E/C:PhD(NP):2013-14: SC) from the National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, India. We acknowledge financial support from the Department of Biotechnology (DBT), Science and Engineering Research Board, Department of Science & Technology, Government of India (SERB-DST), New Delhi and National Institute of Mental Health and Neuro Sciences (NIMHANS), Bengaluru, India.
S.J.T., T.R.R., and B.S.S.R. conceptualized and designed the experiments; S.J.T. and S.C. performed the experiments and analyzed the data; B.N.S, T.R.R., and B.S.S.R. contributed to reagents/materials/analysis tools; and S.J.T., S.C., B.N.S, T.R.R., and B.S.S.R. wrote the manuscript.
Compliance with Ethical Standards
Conflict of Interest
The authors declare no conflict of interest.
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