1. Injection of galanin into the dorsal hippocampus impairs emotional memory independent of 5-HT 1A receptor activation.
- Author
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Stiedl O, Kuteeva E, Hökfelt T, and Ögren SO
- Subjects
- Animals, Avoidance Learning drug effects, Behavior, Animal drug effects, Galanin administration & dosage, Male, Mice, Inbred C57BL, Mice, Emotions, Galanin pharmacology, Hippocampus drug effects, Memory drug effects, Memory Consolidation drug effects, Receptor, Serotonin, 5-HT1A drug effects
- Abstract
There is evidence that interaction between the neuropeptide galanin and the 5-HT
1A receptor represents an integrative mechanism in the regulation of serotonergic neurotransmission. Thus, in rats intracerebroventricular (i.c.v.) galanin did not impair retention in the passive avoidance (PA) test 24 h after training, but attenuated the retention deficit caused by subcutaneous (s.c.) administration of the 5-HT1A receptor agonist 8-OH-DPAT. This impairment has been linked to postsynaptic 5-HT1A receptor activation. To confirm these results in mice, galanin was infused i.c.v. (1 nmol/mouse) in C57BL/6/Bkl mice 30 min prior to training followed by s.c. injection (0.3 mg/kg) of 8-OH-DPAT or saline 15 min before PA training. In line with previous results, i.c.v. galanin significantly attenuated the PA impairment caused by 5-HT1A receptor activation in mice. To study if the galanin 5-HT1A receptor interaction involved the dorsal hippocampus, galanin (1 nmol/mouse) was directly infused into this brain region alone or in combination with s.c. 8-OH-DPAT. However, unlike i.c.v. galanin, galanin infusion into the dorsal hippocampus alone impaired PA retention and failed to attenuate the 8-OH-DPAT-mediated PA impairment. These results indicate that the ability of i.c.v. galanin to modify 5-HT1A receptor activation is not directly mediated via receptor interactions in the dorsal hippocampus. Instead, the galanin-mediated PA impairment suggests an important inhibitory role of galanin receptors in the dorsal hippocampus for acquisition (encoding) and/or consolidation of emotional memory. In addition, the interaction between galanin and 5-HT1A receptors probably involves a wide serotonergic network that is important for the integration of emotional and cognitive behaviors., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)- Published
- 2021
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