Neural mechanism of early maternal deprivation leading to increased pain emotion in adult rats
DONG Ya1, CHEN Chun2, LI Haijing1, LIN Li1, LIN Zhenlang1.
1.Department of Neonatal Pediatrics, the Second Affiliated Hospital & Yuying Children’s Hospital of Wenzhou Medical University, Wenzhou 325027, China; 2.Department of Pediatrics, the First Affiliated Hospital Zhejiang University School of Medicine,Hangzhou 310000, China
DONG Ya,CHEN Chun,LI Haijing, et al. Neural mechanism of early maternal deprivation leading to increased pain emotion in adult rats[J]. JOURNAL OF WEZHOU MEDICAL UNIVERSITY, 2022, 52(9): 741-746.
Abstract：Objective: To explore the central nervous mechanism of early maternal deprivation on the aggravation of pain emotion in rats. Methods: The random number table method was used to divide the neonatal rats into the maternal deprivation group and the control group according to their litters. By restricting the nesting material, a rat maternal deprivation model was established. The control group was given a sufficient amount of nesting material, while the maternal deprivation group was given 1/3 of the nesting material of the control Group, with other conditions being the same. At the age of 2 months, the body weight of the rats was recorded, and the Formalin-induced conditioned place avoidance (F-CPA) model was performed. After the rats were anesthetized, their cerebrospinal fluid and blood as well as the brain were collected. The levels of adrenocorticotropic hormone in cerebrospinal fluid and blood cortisol were determined by ELISA. The number of c-Fos protein positive cells in
rat brain tissue was observed by immunohistochemical staining. Results: At the age of 2 months, the body weight of the rats in the maternal deprivation group was [(300.1±67.2)g] and the control group was [(294.3±59.3)g].There was no significant difference in the body weight between the two groups (P>0.05). The ACTH concentration in the cerebrospinal fluid of the rats in the control group after the test on the 4th day was (173.6±21.7)ng/mL, while it was (186.2±16.0)ng/mL in the maternal deprivation group, with the maternal deprivation group significantly higher than the control group (P<0.05). The blood cortisol concentration of the rats in the control group after the test on the 4th day was (141.7±15.4)ng/mL, while it was (158.0±22.7)ng/mL in the maternal deprivation group,with the maternal deprivation group significantly higher than the control group (P<0.05). The formalin-induced conditioned place avoidance model (F-CPA) aroused the maternal deprivation group with the expression of c-Fos protein in MITN and IC of the medullary plate, while the F-CPA awakened the control group with no expression at this site. Conclusion: In the early stage, by restricting the nesting material of mother mice, the changes of blood cortisol and ACTH of cerebrospinal fluid in offspring mice can be induced, and a new model of maternal deprivation was established. The abnormal expression of c-Fos protein in MITN and IC of the medullary plate suggest that this part may be the neuroanatomical structure related to the emotion of maternal deprivation pain in the neonatal period.
