Physiology & behavior
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Physiology & behavior · Jun 2004
Comparative StudyChanges in anxiety-related behaviors and hypothalamic-pituitary-adrenal activity in mice lacking the 5-HT-3A receptor.
The serotonin-3 (5-HT-3A) receptor has been localized in limbic and brainstem structures that regulate anxiety-related behavior and hypothalamic-pituitary-adrenal (HPA) activity, but its role in regulating anxiety-related behaviors is equivocal, and evidence for its role in regulating HPA activity is limited. Therefore, we used 5-HT-3A receptor knockout (KO) mice to further study these issues. Behavior in the elevated plus maze, open field, light-dark box and after Pavlovian fear conditioning was examined in addition to HPA activity under basal and acute stress conditions. ⋯ In addition, lower vasopressin mRNA in the paraventricular nucleus of the hypothalamus (PVN) and higher corticotropin-releasing hormone (CRH) mRNA in the central amygdala were observed in KO compared to WT mice. Therefore, deletion of the 5-HT-3A receptor revealed an important role for this receptor in regulating HPA responses to acute stress and a potential interaction between the 5-HT-3A receptor and CRH in the amygdala. Together, these data suggest that the 5-HT-3A receptor does not have a unitary role in the regulation of anxiety- and fear-related behaviors but has a potentially substantial role in the regulation of HPA activity.
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Physiology & behavior · Jun 2004
Comparative StudyNonevoked facial pain in rats following infraorbital nerve injury: a parametric analysis.
Unilateral chronic constriction injury to the infraorbital nerve (IoN-CCI) induces an increase in face-grooming behavior that is not part of normal body grooming (i.e., "isolated face grooming"). Despite the validity of isolated face grooming as a measure of spontaneous neuropathic pain, variation between rats in postoperative face grooming has limited its usefulness. We examined whether performing bilateral rather than unilateral IoN surgery could induce a more stable face-grooming behavior. ⋯ The effects of cage size were mostly related to differences in episode duration; that is, rats performed longer face-grooming episodes in the small compared to the large observation cage. The present data confirm previous reports that isolated face grooming is a more sensitive measure than the total amount of face grooming. Bilateral IoN surgery does not seem to offer a more stable outcome measure; increases in isolated face grooming were, however, more clearly observed in the small cage.