Apelin-13 enhances contextual fear extinction in rats. (1st November 2019)

• Record Type: Journal Article
• Authors: Chen, Fang-Ling; Li, Jie; Wang, Bo; Tian, Shao-Wen; Long, Chen
• Is Part Of: Neuroscience letters. Volume 712(2019)
• Publication Date: 2019-11-01
• Subjects: Apelin-13 -- Fear extinction -- Memory -- PTSD -- Rats; Neurology -- Periodicals; Neurology -- Periodicals; Research -- Periodicals; Neurologie -- Périodiques; Neuroanatomie -- Périodiques; Neuropharmacologie -- Périodiques; Neurophysiologie -- Périodiques; Neurology; Periodicals; Electronic journals; 617.48
• DOI: 10.1016/j.neulet.2019.134487
• Languages: English
• ISSNs: 0304-3940

Abstract

Highlights: Apelin-13 enhances within-session contextual fear extinction. Apelin-13 enhances between-session contextual fear extinction. Apelin-13 has no effect on baseline freezing response. Apelin-13 has no effect on locomotor activity and anxiety level. Abstract: Fear extinction is considered as a new learning process that is valid to model features of post-traumatic stress disorder (PTSD). The neuropeptide apelin, such as apelin-13, apelin-17 and apelin-36, are endogenous ligands of the G-protein coupled receptor APJ. Apelin and its receptor APJ are widely distributed in the central nervous system. Accumulating evidence suggests the critical role of apelin-13 in modulation of learning and memory, however, its specific role in fear extinction remains unclear. In the present study, we investigated the effect of apelin-13 administration on contextual fear extinction in rats. The behavioral procedure included four sessions: habitation, conditioning, extinction training and extinction recall. Rats received intracerebroventricular infusion of apelin-13 (3 or 6 μg) 0.5 h prior to the extinction training. Percentage of freezing was utilized to assess the conditioned fear response. Results showed that apelin-13, with the dose of 6 but not 3 μg, significantly decreased freezing response during both extinction training and extinction recall test sessions. Furthermore, apelin-13 did not affect the levels of baseline freezing, locomotor activity and anxiety. The results suggest that apelin-13 dose-dependently enhances contextual fear extinction, and may function as a novel target for treatment of PTSD.