Objective: Assessment of behavioral activation, arousal, and agitation in a stressful aquatic environment following CRF infusion into the locus coeruleus
Materials & Equipment Checklist
4 items2 from ConductScience
Gather these items before starting the experiment. Check off items as you prepare.
Equipment3
Not explicitly stated • Not mentioned • Not mentioned • Not mentioned
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Protocol Steps
View Abstract
The present series of experiments tested the hypothesis that the behavioral activating and anxiogenic effects produced by intraventricular administration of corticotropin-releasing factor (CRF) may be mediated by noradrenergic neurons in the brain-stem locus coeruleus (LC). Results showed that infusion of CRF into the LC (100 ng) significantly increased nonambulatory spontaneous motor activity measured in photocell cages; ambulatory (i.e., locomotor) activity was not altered. In the modified Porsolt swim test, which examines arousal and agitation in a stressful situation, significant behavioral activation (i.e., decreased floating) was seen following infusion of CRF (10 ng) into the LC; a 500 ng dose of CRF was necessary to produce similar effects following infusion into the lateral ventricle. The results of these 2 tests suggest that the behavioral activating effects of CRF in the LC may be related to arousing or stress-related effects, rather than to increased locomotor activity per se. Anxiogenic activity was assessed in animals placed in an open field containing a small, darkened compartment. Infusion or CRF into the LC (1–100 ng) significantly increased the time spent in the compartment and decreased the amount of time spent exploring the outside of the compartment or venturing into the inner squares of the open field, all indices of anxiogenic behavior. Biochemical studies showed that bilateral infusion of CRF into the LC produced significant increases in the concentration of the norepinephrine metabolite 3,4-dihydroxyphenylglycol in such forebrain projection areas of the LC as the amygdala and posterior hypothalamus. These data, taken together, suggest that CRF produces its behavioral activating and anxiogenic effects, at least in part, by increasing the activity of LC noradrenergic neurons.
1
CRF infusion into locus coeruleus
Bilateral infusion of corticotropin-releasing factor into the locus coeruleus at specified doses
Not explicitly statedNot mentioned
Note: Doses tested: 1-100 ng for anxiogenic assessment, 10 ng for modified Porsolt swim test, 100 ng for photocell cage assessment
View evidence from paper
“infusion of CRF into the LC (100 ng) significantly increased nonambulatory spontaneous motor activity; infusion of CRF (10 ng) into the LC”
2
Photocell cage assessment
Measure nonambulatory spontaneous motor activity and ambulatory (locomotor) activity following CRF infusion
Not explicitly statedNot mentioned
Note: 100 ng CRF dose used for this test
View evidence from paper
“nonambulatory spontaneous motor activity measured in photocell cages; ambulatory (i.e., locomotor) activity was not altered”
3
Modified Porsolt swim test
Place animals in stressful aquatic environment and measure behavioral activation through decreased floating behavior
Note: 10 ng CRF dose into LC produced significant behavioral activation; 500 ng dose into lateral ventricle produced similar effects
View evidence from paper
“In the modified Porsolt swim test, which examines arousal and agitation in a stressful situation, significant behavioral activation (i.e., decreased floating) was seen following infusion of CRF (10 ng)”
4
Open field anxiogenic assessment
Place animals in open field containing small darkened compartment and measure time spent in compartment and exploration behavior
Not explicitly statedNot mentioned
Open Field Test Arena
Matches: Open field apparatus with darkened compartment
Note: CRF doses of 1-100 ng tested; measured time in compartment, time exploring outside, and time in inner squares
View evidence from paper
“Infusion or CRF into the LC (1–100 ng) significantly increased the time spent in the compartment and decreased the amount of time spent exploring”
5
Biochemical analysis
Measure norepinephrine metabolite 3,4-dihydroxyphenylglycol concentration in forebrain projection areas following bilateral CRF infusion into locus coeruleus
Not explicitly statedNot mentioned
Note: Measured in amygdala and posterior hypothalamus
View evidence from paper
“Bilateral infusion of CRF into the LC produced significant increases in the concentration of the norepinephrine metabolite 3,4-dihydroxyphenylglycol in such forebrain projection areas of the LC as the amygdala and posterior hypothalamus”
Subjects / Specimens
Species
Not explicitly stated
Strain
Not explicitly stated
Age
Not explicitly stated
Sex
unknown
Weight
Not explicitly stated
Animals received bilateral infusion of CRF into the locus coeruleus