TY - JOUR
T1 - Distribution of neuronal melanocortins in the spadefoot toad Spea multiplicata and effects of stress
AU - Venkatesan, S.
AU - Carr, James A.
N1 - Copyright:
Copyright 2007 Elsevier B.V., All rights reserved.
PY - 2001
Y1 - 2001
N2 - 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 radio-immunoassay (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.
AB - 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 radio-immunoassay (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.
KW - Adrenocorticotropin
KW - Amphibian
KW - Endorphin
KW - Melanocyte-stimulating hormone
KW - Nucleus accumbens basal ganglia
KW - Pro-opiomelanocortin
KW - Radioimmunoassay
KW - Striatum
UR - http://www.scopus.com/inward/record.url?scp=0034884658&partnerID=8YFLogxK
U2 - 10.1159/000047233
DO - 10.1159/000047233
M3 - Article
C2 - 11509823
AN - SCOPUS:0034884658
VL - 57
SP - 150
EP - 160
JO - Brain, Behavior and Evolution
JF - Brain, Behavior and Evolution
SN - 0006-8977
IS - 3
ER -