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Social Stress Engages Neurochemically-Distinct Afferents to the Rat Locus Coeruleus Depending on Coping Strategy.

Reyes BA, Zitnik G, Foster C, Van Bockstaele EJ, Valentino RJ - eNeuro (2015)

Bottom Line: Sections through the nucleus paragigantocellularis (PGi) and central amygdalar nucleus (CNA), major sources of enkephalin (ENK) and CRF LC afferents, respectively, were immunocytochemically processed to detect c-fos, FG, and CRF or ENK.Together, these results indicate that the establishment of different coping strategies to social stress is associated with changes in the circuitry that regulates activity of the brain norepinephrine system.This may underlie differential vulnerability to the consequences of social stress that characterize these different coping strategies.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pharmacology and Physiology, College of Medicine, Drexel University , Philadelphia, Pennsylvania 19102.

ABSTRACT
Stress increases vulnerability to psychiatric disorders, partly by affecting brain monoamine systems, such as the locus coeruleus (LC)-norepinephrine system. During stress, LC activity is coregulated by corticotropin-releasing factor (CRF) and endogenous opioids. This study identified neural circuitry that regulates LC activity of intruder rats during the resident-intruder model of social stress. LC afferents were retrogradely labeled with Fluorogold (FG) and rats were subjected to one or five daily exposures to an aggressive resident. Sections through the nucleus paragigantocellularis (PGi) and central amygdalar nucleus (CNA), major sources of enkephalin (ENK) and CRF LC afferents, respectively, were immunocytochemically processed to detect c-fos, FG, and CRF or ENK. In response to a single exposure, intruder rats assumed defeat with a relatively short latency (SL). LC neurons, PGI-ENK LC afferents, and CNA-CRF LC afferents were activated in these rats as indicated by increased c-fos expression. With repeated stress, rats exhibited either a SL or long latency (LL) to defeat and these strategies were associated with distinct patterns of neuronal activation. In SL rats, LC neurons were activated, as were CNA-CRF LC afferents but not PGI-ENK LC afferents. LL rats had an opposite pattern, maintaining activation of PGi-ENK LC afferents but not CNA-CRF LC afferents or LC neurons. Together, these results indicate that the establishment of different coping strategies to social stress is associated with changes in the circuitry that regulates activity of the brain norepinephrine system. This may underlie differential vulnerability to the consequences of social stress that characterize these different coping strategies.

No MeSH data available.


Related in: MedlinePlus

FG injection and retrograde labeling. Ai–Ci, Schematic diagrams adapted from the Rat Brain Atlas (Paxinos and Watson, 1998) showing the anteroposterior levels of the representative injection site (A) and retrograde labeling (B,C). Aii, Bright-field photomicrograph showing a representative FG injection within the rat LC. Bii–Cii, Bright-field photomicrographs of representative retrograde labeling in the nucleus PGi (Bii at ∼Plate 67; Paxinos and Watson, 1998) and CNA (Cii at ∼Plate 26; Paxinos and Watson, 1998) following FG injection into the LC. The arrows indicate immunoperoxidase labeled cells. Scale bars: A, 50 μm; B, C, 25 μm.
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Figure 1: FG injection and retrograde labeling. Ai–Ci, Schematic diagrams adapted from the Rat Brain Atlas (Paxinos and Watson, 1998) showing the anteroposterior levels of the representative injection site (A) and retrograde labeling (B,C). Aii, Bright-field photomicrograph showing a representative FG injection within the rat LC. Bii–Cii, Bright-field photomicrographs of representative retrograde labeling in the nucleus PGi (Bii at ∼Plate 67; Paxinos and Watson, 1998) and CNA (Cii at ∼Plate 26; Paxinos and Watson, 1998) following FG injection into the LC. The arrows indicate immunoperoxidase labeled cells. Scale bars: A, 50 μm; B, C, 25 μm.

Mentions: Of 14 rats (7 control, 7 stress) that were injected with FG into the LC 11 (5 control, 3 stress LL rats and 3 stress SL rats) had optimally placed injections that targeted the region of LC. Figure 1Aii shows a representative bright-field photomicrograph depicting an FG injection site into the LC. FG injections into the LC yielded consistent retrograde labeling of perikarya in both the PGi and the CNA in all cases examined (Fig. 1B,C). The mean number of retrogradely labeled neurons after repeated social stress was not different between experimental groups in either the PGi (F(2,8) = 2.034, p = 0.169) or CNA (F(2,8) = 1.511, p = 0.278; Tables 1, 2).


Social Stress Engages Neurochemically-Distinct Afferents to the Rat Locus Coeruleus Depending on Coping Strategy.

Reyes BA, Zitnik G, Foster C, Van Bockstaele EJ, Valentino RJ - eNeuro (2015)

FG injection and retrograde labeling. Ai–Ci, Schematic diagrams adapted from the Rat Brain Atlas (Paxinos and Watson, 1998) showing the anteroposterior levels of the representative injection site (A) and retrograde labeling (B,C). Aii, Bright-field photomicrograph showing a representative FG injection within the rat LC. Bii–Cii, Bright-field photomicrographs of representative retrograde labeling in the nucleus PGi (Bii at ∼Plate 67; Paxinos and Watson, 1998) and CNA (Cii at ∼Plate 26; Paxinos and Watson, 1998) following FG injection into the LC. The arrows indicate immunoperoxidase labeled cells. Scale bars: A, 50 μm; B, C, 25 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4660134&req=5

Figure 1: FG injection and retrograde labeling. Ai–Ci, Schematic diagrams adapted from the Rat Brain Atlas (Paxinos and Watson, 1998) showing the anteroposterior levels of the representative injection site (A) and retrograde labeling (B,C). Aii, Bright-field photomicrograph showing a representative FG injection within the rat LC. Bii–Cii, Bright-field photomicrographs of representative retrograde labeling in the nucleus PGi (Bii at ∼Plate 67; Paxinos and Watson, 1998) and CNA (Cii at ∼Plate 26; Paxinos and Watson, 1998) following FG injection into the LC. The arrows indicate immunoperoxidase labeled cells. Scale bars: A, 50 μm; B, C, 25 μm.
Mentions: Of 14 rats (7 control, 7 stress) that were injected with FG into the LC 11 (5 control, 3 stress LL rats and 3 stress SL rats) had optimally placed injections that targeted the region of LC. Figure 1Aii shows a representative bright-field photomicrograph depicting an FG injection site into the LC. FG injections into the LC yielded consistent retrograde labeling of perikarya in both the PGi and the CNA in all cases examined (Fig. 1B,C). The mean number of retrogradely labeled neurons after repeated social stress was not different between experimental groups in either the PGi (F(2,8) = 2.034, p = 0.169) or CNA (F(2,8) = 1.511, p = 0.278; Tables 1, 2).

Bottom Line: Sections through the nucleus paragigantocellularis (PGi) and central amygdalar nucleus (CNA), major sources of enkephalin (ENK) and CRF LC afferents, respectively, were immunocytochemically processed to detect c-fos, FG, and CRF or ENK.Together, these results indicate that the establishment of different coping strategies to social stress is associated with changes in the circuitry that regulates activity of the brain norepinephrine system.This may underlie differential vulnerability to the consequences of social stress that characterize these different coping strategies.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pharmacology and Physiology, College of Medicine, Drexel University , Philadelphia, Pennsylvania 19102.

ABSTRACT
Stress increases vulnerability to psychiatric disorders, partly by affecting brain monoamine systems, such as the locus coeruleus (LC)-norepinephrine system. During stress, LC activity is coregulated by corticotropin-releasing factor (CRF) and endogenous opioids. This study identified neural circuitry that regulates LC activity of intruder rats during the resident-intruder model of social stress. LC afferents were retrogradely labeled with Fluorogold (FG) and rats were subjected to one or five daily exposures to an aggressive resident. Sections through the nucleus paragigantocellularis (PGi) and central amygdalar nucleus (CNA), major sources of enkephalin (ENK) and CRF LC afferents, respectively, were immunocytochemically processed to detect c-fos, FG, and CRF or ENK. In response to a single exposure, intruder rats assumed defeat with a relatively short latency (SL). LC neurons, PGI-ENK LC afferents, and CNA-CRF LC afferents were activated in these rats as indicated by increased c-fos expression. With repeated stress, rats exhibited either a SL or long latency (LL) to defeat and these strategies were associated with distinct patterns of neuronal activation. In SL rats, LC neurons were activated, as were CNA-CRF LC afferents but not PGI-ENK LC afferents. LL rats had an opposite pattern, maintaining activation of PGi-ENK LC afferents but not CNA-CRF LC afferents or LC neurons. Together, these results indicate that the establishment of different coping strategies to social stress is associated with changes in the circuitry that regulates activity of the brain norepinephrine system. This may underlie differential vulnerability to the consequences of social stress that characterize these different coping strategies.

No MeSH data available.


Related in: MedlinePlus