Evidence for corticotropin releasing factor (CRF) synthesis in the preoptic nucleus of Xenopus laevis tadpoles

Notenboom, C. D.; Terlou, M.; Maten, Marianne L.

doi:10.1007/bf00219304

Cited by 13 publications

(2 citation statements)

References 18 publications

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“…Early studies in an amphibian ( Bufo melanosticus ) found an elevation in plasma corticosteroids after electrical stimulation of the POA, ventral hypothalamus, or the median eminence, but not after stimulation of other brain regions (52). Furthermore, lesioning of the ventral region of the POA in X. laevis tadpoles caused the pituitary corticotropes to regress (53). In the present study, we investigated the effects of a physical stressor, handling/shaking on CRH neuronal physiology in X. laevis .…”

Section: Discussionmentioning

confidence: 99%

Distribution and Acute Stressor‐Induced Activation of Corticotrophin‐Releasing Hormone Neurones in the Central Nervous System of Xenopus laevis

Yao

Westphal

Denver

2004

J Neuroendocrinology

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In mammals, corticotrophin-releasing hormone (CRH) and related peptides are known to play essential roles in the regulation of neuroendocrine, autonomic and behavioural responses to physical and emotional stress. In nonmammalian species, CRH-like peptides are hypothesized to play similar neuroendocrine and neurocrine roles. However, there is relatively little detailed information on the distribution of CRH neurones in the central nervous system (CNS) of nonmammalian vertebrates, and there are currently no comparative data on stress-induced changes in CRH neuronal physiology. We used a specific, affinity-purified antibody raised against synthetic Xenopus laevis CRH to map the distribution of CRH in the CNS of juvenile South African clawed frogs. We then analysed stress-induced changes in CRH immunoreactivity (CRH-ir) throughout the CNS. We found that CRH-positive cell bodies and fibres are widely distributed throughout the brain and rostral spinal cord of juvenile X. laevis. Strong CRH-immunoreactivity (ir) was found in cell bodies and fibres in the anterior preoptic area (POA, an area homologous to the mammalian paraventricular nucleus) and the external zone of the median eminence. Specific CRH-ir cell bodies and fibres were also identified in the septum, pallium and striatum in the telencephalon; the amygdala, bed nucleus of the stria terminalis and various hypothalamic and thalamic nuclei in the diencephalon; the tectum, torus semicircularis and tegmental nuclei of the mesencephalon; the cerebellum and locus coeruleus in the rhombencephalon; and the ventral horn of the rostral spinal cord. To determine if exposure to an acute physical stressor alters CRH neuronal physiology, we exposed juvenile frogs to shaking/handling and conducted morphometric analysis. Plasma corticosterone was significantly elevated by 30 min after exposure to the stressor and continued to increase up to 6 h. Morphometric analysis of CRH-ir after 4 h of stress showed a significant increase in CRH-ir in parvocellular neurones of the anterior preoptic area, the medial amygdala and the bed nucleus of the stria terminalis, but not in other brain regions. The stress-induced increase in CRH-ir in the POA was associated with increased Fos-like immunoreactivity (Fos-LI), and confocal microscopy showed that CRH-ir colocalized with Fos-LI in a subset of Fos-LI-positive neurones. Our results support the view that the basic pattern of CNS CRH expression arose early in vertebrate evolution and lend further support to earlier studies suggesting that amphibians may be a transitional species for descending CRH-ergic pathways. Furthermore, CRH neurones in the frog brain exhibit changes in response to a physical stressor that parallel those seen in mammals, and thus are likely to play an active role in mediating neuroendocrine, behavioural and autonomic stress responses.

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Section: Discussionmentioning

confidence: 99%

Distribution and Acute Stressor‐Induced Activation of Corticotrophin‐Releasing Hormone Neurones in the Central Nervous System of Xenopus laevis

Yao

Westphal

Denver

2004

J Neuroendocrinology

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“…The distribution and development of hypothalamic neuroendocrine cells and fibers is well documented in mammals (Ugrumov, 1991). In amphibians, however, there have been few reports on the development of the 0 1995 WILEY-LISS, INC. hypothalamus (Carr and Norris, 1990;Notenboom et al, 1976). In addition, almost no studies have been attempted to investigate the correlational development of the hypothalamo-adenohypophysial and hypothalamo-neurohypophysial systems in species higher than amphibians.…”

Section: Hypothalamus Immunohistochemistry Xenopus Zaeuismentioning

confidence: 99%

Immunohistochemical studies on the development of the hypothalamo‐hyophysial system in Xenopus laevis

1995

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These results suggest the following three chronological steps in the development of hypothalamo-hypophysial systems and their target organs: independent development of target organs at early developmental stages; appearance of hypophysial hormones to control the development of target organs at middle developmental stages; appearance of hypothalamic hormones to control the function or maturation of the hypophysis at late developmental stages.

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Cerebrospinal fluid-contacting neurons and other somatostatin-immunoreactive perikarya in brains of tadpoles of Xenopus laevis

1982

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In untreated tadpoles of Xenopus laevis, stage 60 (Nieuwkoop and Faber 1956), somatostatin-immunoreactive perikarya and fiber networks are already discernible in the pallium and the septum, as well as in the anterior and posterior hypothalamus. In addition, somatostatin-immunoreactive cerebrospinal fluid (CSF)-contacting neurons were found in the periventricular gray of the most caudal division of the ventral tuber cinereum. The results are discussed with respect to the inhibitory influence of the system of CSF-contacting and other somatostatin-immunoreactive neurons on the anterior pituitary and other target sites, especially during the climax of metamorphosis.

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Evidence for corticotropin releasing factor (CRF) synthesis in the preoptic nucleus of Xenopus laevis tadpoles

Cited by 13 publications

References 18 publications

Distribution and Acute Stressor‐Induced Activation of Corticotrophin‐Releasing Hormone Neurones in the Central Nervous System of Xenopus laevis

Distribution and Acute Stressor‐Induced Activation of Corticotrophin‐Releasing Hormone Neurones in the Central Nervous System of Xenopus laevis

Immunohistochemical studies on the development of the hypothalamo‐hyophysial system in Xenopus laevis

Cerebrospinal fluid-contacting neurons and other somatostatin-immunoreactive perikarya in brains of tadpoles of Xenopus laevis

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