Histamine in the central nervous system is produced mainly in the tuberomammillary nucleus (TMN) and is implicated in learning and memory as well as sleep and wakefulness, feeding and drinking, and neuroendocrine regulation. Previously, we demonstrated that and promote the recall of forgotten object memories. However, whether activation of histamine neurons influences memory recall and what kind of physiological stimulus activates histamine neurons are not clear. In this study, first, we examined whether chemogenetic activation of histamine neurons in the TMN affect retrieval of forgotten object and spatial and fear memories in mice. The pre-test activation of histamine neurons promoted retrieval of object and spatial memories. Next, we used fiber photometry to measure the activity of histamine neurons. We virally targeted GCaMP6, a genetically-encoded calcium indicator, was Cre-dependently expressed into histamine neurons in the TMN of HDC-Cre mice, and implanted an optic fiber was implanted in the upper part of the TMN. We found that various physiological stimuli, including auditory stimulus and sucrose presentation, increased activity of histamine neurons. These physiological stimuli may influence memory performance through activation of histamine neurons.
Brain histamine is produced mainly in the tuberomammillary nucleus (TMN) and is implicated in learning and memory as well as wakefulness and feeding. Previously, we demonstrated histamine H 3 receptor inverse agonists upregulate histamine release in the perirhinal cortex and promote the recall of forgotten object memories. However, since H 3 receptors are expressed in non-histaminergic neurons as well as histaminergic neurons, other neurotransmitter systems could be involved in the memory recovery. In this study, we examined whether chemogenetic manipulation of histamine neurons modulates memory retrieval in mice. We virally targeted hM3Dq, the excitatory DREADD receptor, to histamine neurons in the TMN of HDC-Cre mice. In a training session of the novel object recognition task, mice were placed in the field, in which two identical objects were positioned. One week later, they underwent a test session where one familiar and one novel object were presented. The pre-test injection of CNO to the mice receiving AAV-DIO-hM3Dq enhanced the discrimination between two objects as compared to controls. The activation of histamine neurons had no effect on anxiety-like behavior in the elevated plus maze test. These findings indicate that activation of histamine neurons enhances retrieval of a forgotten long-term object memory.
No abstract
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.