Nitrergic neurons of the dorsal raphe nucleus encode information about stress duration.

India S Nichols,Chuma Okere,J Christopher Ehlen,Mary I Jones,Brittany Bush,Allison Brager,Ketema Paul,Cloe Gray,Godwin Ananaba,Alexandra Kavushansky

doi:10.1371/journal.pone.0187071

India S Nichols, Chuma Okere + Show 8 more

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https://doi.org/10.1371/journal.pone.0187071

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Journal: PloS one	Publication Date: Nov 10, 2017
Citations: 4	License type: CC BY 4.0

Affiliation: Clark Atlanta University, Morehouse School of Medicine

Abstract

Nitrergic neurons of the dorsal raphe nucleus (DRN) may play a role in physiological stress responses. The caudal lateral wings (CLW) are unique compared to other rostral-caudal DRN sub-regions because they contain distinct nitric oxide (NO) synthase (NOS) populations that are independent of tryptophan hydroxylase (TPH). NOS neurons in the CLW are also highly activated during acute restraint stress. However, the effects of acute stress duration on NOS activation in the CLW are unclear. Here NADPH-d, an index of NOS activity, is used to show that sub-regions of the DRN have differential NOS activation in response to 6 hours of restraint stress in rats. We report increased NOS activity through 6 hours of restraint in the caudal lateral wings and ventromedial sub-regions. These data suggest that, NOS neurons may play a dynamic role in the response to stress duration.

Highlights

The sub-regions of the dorsal raphe nucleus (DRN) are functionally organized based on the localization pattern of serotonin (5-HT) producing neurons
There were no signs of health issues immediately after the rats were removed from the restraints
Study of the role nitric oxide synthase (NOS) plays in the stress response is important because it has been reported that NOS activation in the DRN has anxiolytic-like and antidepressant-like effects [19]

Summary

Introduction

The sub-regions of the dorsal raphe nucleus (DRN) are functionally organized based on the localization pattern of serotonin (5-HT) producing neurons. Serotonergic neurons in the DRN are found in rostro-caudal and mediolateral dimensions where each rostral or caudal region contains a dorsomedial, ventromedial, and bilateral (lateral wings) sub-region (Fig 1) [1]. Neuronal nitric oxide synthase (NOS) neurons manifest in a unique topographical distribution and co-localization pattern across the DRN [2]. Most of the neurons in the dorsomedial and ventromedial DRN, collectively known as the midline, display both NOS and tryptophan hydroxylase (TPH), but neurons in the caudal lateral wing (CLW) display either NOS or TPH exclusively [2, 3].

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