α-Melanocyte-Stimulating Hormone and Habituation of Prey-Catching Behavior in the Texas Toad, Bufo speciosus

Olsen, Christopher M.; Lovering, Andrew T.; Carr, James A.

doi:10.1006/hbeh.1999.1531

Cited by 15 publications

(12 citation statements)

References 32 publications

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“…The caudal ventral striatum in particular appears to play an important role in visually-guided feeding, as lesions in this brain area eliminate prey-oriented movement [Finkenstädt, 1989]. Interestingly, melanocortins reduce prey-oriented turning movements and facilitate habituation to a non-rewarding prey-stimulus in B. cognatus [Carpenter and Carr, 1996] and B. speciosus [Olsen et al, 1999]. Whether melanocortin effects on visually-guided feeding are mediated by receptors in the basal ganglia is an area for future research.…”

Section: Discussionmentioning

confidence: 99%

“…In rats, melanocortins partially mediate restraint stress-induced anorexia [Vergoni et al, 1999], a model that has been com-pared to anorexia nervosa in humans because of the purely psychological (as opposed to physical or visceral) nature of the stressor [Vergoni et al, 2000]. Melanocortins (αMSH, ACTH, ACTH 4-10) reduce prey-oriented turning responses and facilitate the acquisition of habituation in the toads B. cognatus [Carpenter and Carr, 1997] and B. speciosus [Olsen et al, 1999]. Exposure of toads (Bufo) to unrelated stressors [confinement, Kim and Carr, 1997;ether vapors, Olsen et al, 1999] produces regional alterations in brain αMSH and also inhibits feeding behavior [Carr et al, 2000].…”

Section: Discussionmentioning

confidence: 99%

“…We have previously demonstrated that exposure to ether vapors is a potent stressor in anurans as gauged by a greater than 4-fold increase in plasma corticosterone levels within 60 min of exposure [Olsen et al, 1999]. In the present study toads were placed into a closed jar containing ether vapors for 45 s and then returned immediately to their home aquaria.…”

Section: Ether Stress Proceduresmentioning

confidence: 99%

“…Evidence that neuronal melanocortins play a role in the stress response is not restricted to mammals. Previous work in our lab indicates that exposure of toads (Bufo speciosus) to a noxious stimulus selectively alters regional brain αMSH content [Kim and Carr, 1997;Olsen et al, 1999] and reduces prey-oriented turning reactions [Carr et al, 2000].…”

Section: Introductionmentioning

confidence: 99%

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Distribution of Neuronal Melanocortins in the Spadefoot Toad <i>Spea multiplicata</i> and Effects of Stress

Venkatesan

Carr²

2001

Brain Behav Evol

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We examined the effects of an acute stressor on regional alpha-melanocyte-stimulating hormone (αMSH) content in the New Mexican spadefoot toad, Spea multiplicata. We first used immunocytochemistry along with radioimmunoassay (RIA) to examine the distribution of pro-opiomelanocortin (POMC) neurons in the brain of Spea. Neurons immunoreactive for αMSH, β-endorphin, and corticotropin were observed in the preoptic nucleus and ventral infundibulum of the hypothalamus. Ascending immunoreactive fibers projected to the olfactory nucleus, nucleus accumbens, and striatum. Numerous immunoreactive fibers were also observed in the hypothalamus. The thalamus/hypothalamus (T/HT) contained the greatest concentrations of αMSH as determined by RIA followed by the preoptic area (PO). Levels in the telencephalon, brain stem, and optic tectum (OT) were 14–23 times lower than in the T/HT. Exposure to a brief stressor elevated αMSH levels in the PO and OT. We conclude that Spea possesses two distinct POMC neuronal cell groups, one located in the anterior preoptic area and one located in the ventral infundibulum. Ascending projections to the basal ganglia might play an indirect role in tectal regulation and the control of prey-catching behavior. Exposure to an acute stressor alters brain αMSH content in Spea, although there are regional and temporal differences in the response pattern compared to Bufo. These findings are consistent with the notion that neuronal melanocortins influence how frogs and toads gather information about their environment during stress.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Ether Stress Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Distribution of Neuronal Melanocortins in the Spadefoot Toad <i>Spea multiplicata</i> and Effects of Stress

Venkatesan

Carr²

2001

Brain Behav Evol

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“…Colchicine was administered to the third ventricle of 5 adult male B. speciosus using coordinates previously reported for this species [Olsen et al, 1999]. Briefly, toads were anesthetized with MS-222 and the dorsal skin over the injection site removed using a cautery pen.…”

Section: Colchicine Injectionsmentioning

confidence: 99%

The Organization of CRF Neuronal Pathways in Toads: Evidence that Retinal Afferents Do Not Contribute Significantly to Tectal CRF Content

Carr¹,

Lustgarten²,

Ahmed³

et al. 2010

Brain Behav Evol

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Previous work has suggested that the peptide corticotropin-releasing factor (CRF) acts to inhibit visually guided feeding in anurans, but little is known about potential targets for CRF within the subcortical visuomotor circuitry. Here we investigated the relationship between CRF neuronal organization and visual pathways in toads. CRF-immunoreactive (ir) neurons and fibers were widely distributed throughout the ventral subpallial telencephalon and hypothalamus, although few fibers were found in telencephalic areas, such as the striatum, that are known to project to the tectum in anurans. Large populations of CRF-ir cells were observed in the bed nucleus of the stria terminalis and preoptic area as well as in the ventral infundibular hypothalamus. CRF-ir neurons and fibers also were observed in several midbrain and brain stem areas. Colchicine treatment significantly enhanced CRF-ir neurons and fibers throughout the brain, and revealed CRF-ir cell groups in several brain areas (including the dorsal hypothalamus) that were not observed in untreated animals. Intrinsic CRF-immunoreactive neurons were routinely observed in cell layer 8 and sometimes in layer 6 of the optic tectum in both untreated and colchicine-treated animals. CRF was detected in toad optic tectum by radioimmunoassay, although tectal CRF content was less than that of the hypothalamus and forebrain. Unilateral eye ablation did not affect CRF content of the contralateral optic tectum. We conclude that CRF-producing neurons are widely distributed in several areas of the toad brain known to be involved in regulating the behavioral, autonomic and endocrine response to stressors, including the optic tectum and several brain areas known to project to the optic tectum. Furthermore, retinal afferents do not contribute significantly to tectal CRF content.

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Stress and Reproduction in Amphibians

Carr

2011

Hormones and Reproduction of Vertebrates

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α-Melanocyte-Stimulating Hormone and Habituation of Prey-Catching Behavior in the Texas Toad, Bufo speciosus

Cited by 15 publications

References 32 publications

Distribution of Neuronal Melanocortins in the Spadefoot Toad <i>Spea multiplicata</i> and Effects of Stress

Distribution of Neuronal Melanocortins in the Spadefoot Toad <i>Spea multiplicata</i> and Effects of Stress

The Organization of CRF Neuronal Pathways in Toads: Evidence that Retinal Afferents Do Not Contribute Significantly to Tectal CRF Content

Stress and Reproduction in Amphibians

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