The regulation of the corticomelanotropic cell activity in aves—II. Effect of various peptides on the release of ACTH from dispersed, perfused duck pituitary cells

Characterization of CRF, AVT, and ACTH cDNA and pituitary-adrenal axis function in Japanese quail divergently selected for tonic immobility

“…A synergic effect between AVT and CRF on CORT release has previously been reported in ducks (8). Surprisingly, although both peptides had a secretagogue effect on CORT, a synergic effect was not observed in the present study.…”

“…However, the effects of CRF in birds were investigated in several earlier studies using the ovine CRF peptide (8,61), but subsequent characterization of the chicken CRF sequence (60) showed that it differs from the ovine sequence by 7 out of 41 amino acids. Given these differences in peptide sequence, it could be hypothesized that the weaker potency of CRF in inducing ACTH release observed in previous studies compared with AVT was due to the fact that the natural CRF was different from the ovine CRF.…”

“…Various experimental findings have shown that CRF is more potent than AVP in CORT release in several mammals [rats (19,46,59); ewes (33)]. On the other hand, contradictory results have been reported concerning the respective effects of these two peptides in birds, with CRF being sometimes more active (8,61) and sometimes less active (38,58). To further investigate their respective effects on pituitary activation in LTI and STI genotypes, pharmacological studies were undertaken using CRF or AVT alone or both peptides together.…”

Characterization of CRF, AVT, and ACTH cDNA and pituitary-adrenal axis function in Japanese quail divergently selected for tonic immobility

“…A synergic effect between AVT and CRF on CORT release has previously been reported in ducks (8). Surprisingly, although both peptides had a secretagogue effect on CORT, a synergic effect was not observed in the present study.…”

“…However, the effects of CRF in birds were investigated in several earlier studies using the ovine CRF peptide (8,61), but subsequent characterization of the chicken CRF sequence (60) showed that it differs from the ovine sequence by 7 out of 41 amino acids. Given these differences in peptide sequence, it could be hypothesized that the weaker potency of CRF in inducing ACTH release observed in previous studies compared with AVT was due to the fact that the natural CRF was different from the ovine CRF.…”

“…Various experimental findings have shown that CRF is more potent than AVP in CORT release in several mammals [rats (19,46,59); ewes (33)]. On the other hand, contradictory results have been reported concerning the respective effects of these two peptides in birds, with CRF being sometimes more active (8,61) and sometimes less active (38,58). To further investigate their respective effects on pituitary activation in LTI and STI genotypes, pharmacological studies were undertaken using CRF or AVT alone or both peptides together.…”

Arginine Vasopressin Is a Much More Potent Stimulus to ACTH Release from Ovine Anterior Pituitary Cells than Ovine Corticotropin-Releasing Factor

“…The weaker potency of a host of other peptides and amines with respet to ACTH release found within hypophysiotropic pathways has further streng thened this presumption [ 1.27, 29], In most cases, however, the bioassay of these other peptides and amines has been made on rat anterior pituitary primary cultures or tumor cell lines. There is no doubt from several in vivo and in vitro studies that CRF is the most potent ACTH secretagogue in the rat [1,24,27,29]; recent studies in other species [5,II,15], however, and the data in this paper, would suggest that CRF is not the most potent secretagogue in all species.…”

Exposure to chronic stress downregulates corticosterone responses to acute stressors

“…However, this again allows two possible interpretations: 1) only oCRF and rCRF were tested, which starling CRF receptors may not recognize; or 2) CRF is not an ACTH secretagog in this species. There is evidence that CRF may not be the primary ACTH secretagog in other avian species (8,33). Because no effect was found, CRF was not used in the chronic stress part of the study.…”

Characterization of CRF, AVT, and ACTH cDNA and pituitary-adrenal axis function in Japanese quail divergently selected for tonic immobility

“…A synergic effect between AVT and CRF on CORT release has previously been reported in ducks (8). Surprisingly, although both peptides had a secretagogue effect on CORT, a synergic effect was not observed in the present study.…”

“…However, the effects of CRF in birds were investigated in several earlier studies using the ovine CRF peptide (8,61), but subsequent characterization of the chicken CRF sequence (60) showed that it differs from the ovine sequence by 7 out of 41 amino acids. Given these differences in peptide sequence, it could be hypothesized that the weaker potency of CRF in inducing ACTH release observed in previous studies compared with AVT was due to the fact that the natural CRF was different from the ovine CRF.…”

“…Various experimental findings have shown that CRF is more potent than AVP in CORT release in several mammals [rats (19,46,59); ewes (33)]. On the other hand, contradictory results have been reported concerning the respective effects of these two peptides in birds, with CRF being sometimes more active (8,61) and sometimes less active (38,58). To further investigate their respective effects on pituitary activation in LTI and STI genotypes, pharmacological studies were undertaken using CRF or AVT alone or both peptides together.…”

Arginine Vasopressin Is a Much More Potent Stimulus to ACTH Release from Ovine Anterior Pituitary Cells than Ovine Corticotropin-Releasing Factor

“…The weaker potency of a host of other peptides and amines with respet to ACTH release found within hypophysiotropic pathways has further streng thened this presumption [ 1.27, 29], In most cases, however, the bioassay of these other peptides and amines has been made on rat anterior pituitary primary cultures or tumor cell lines. There is no doubt from several in vivo and in vitro studies that CRF is the most potent ACTH secretagogue in the rat [1,24,27,29]; recent studies in other species [5,II,15], however, and the data in this paper, would suggest that CRF is not the most potent secretagogue in all species.…”

Exposure to chronic stress downregulates corticosterone responses to acute stressors

“…However, this again allows two possible interpretations: 1) only oCRF and rCRF were tested, which starling CRF receptors may not recognize; or 2) CRF is not an ACTH secretagog in this species. There is evidence that CRF may not be the primary ACTH secretagog in other avian species (8,33). Because no effect was found, CRF was not used in the chronic stress part of the study.…”

Characterization of CRF, AVT, and ACTH cDNA and pituitary-adrenal axis function in Japanese quail divergently selected for tonic immobility

“…A synergic effect between AVT and CRF on CORT release has previously been reported in ducks (8). Surprisingly, although both peptides had a secretagogue effect on CORT, a synergic effect was not observed in the present study.…”

“…However, the effects of CRF in birds were investigated in several earlier studies using the ovine CRF peptide (8,61), but subsequent characterization of the chicken CRF sequence (60) showed that it differs from the ovine sequence by 7 out of 41 amino acids. Given these differences in peptide sequence, it could be hypothesized that the weaker potency of CRF in inducing ACTH release observed in previous studies compared with AVT was due to the fact that the natural CRF was different from the ovine CRF.…”

“…Various experimental findings have shown that CRF is more potent than AVP in CORT release in several mammals [rats (19,46,59); ewes (33)]. On the other hand, contradictory results have been reported concerning the respective effects of these two peptides in birds, with CRF being sometimes more active (8,61) and sometimes less active (38,58). To further investigate their respective effects on pituitary activation in LTI and STI genotypes, pharmacological studies were undertaken using CRF or AVT alone or both peptides together.…”

Arginine Vasopressin Is a Much More Potent Stimulus to ACTH Release from Ovine Anterior Pituitary Cells than Ovine Corticotropin-Releasing Factor

“…The weaker potency of a host of other peptides and amines with respet to ACTH release found within hypophysiotropic pathways has further streng thened this presumption [ 1.27, 29], In most cases, however, the bioassay of these other peptides and amines has been made on rat anterior pituitary primary cultures or tumor cell lines. There is no doubt from several in vivo and in vitro studies that CRF is the most potent ACTH secretagogue in the rat [1,24,27,29]; recent studies in other species [5,II,15], however, and the data in this paper, would suggest that CRF is not the most potent secretagogue in all species.…”

Exposure to chronic stress downregulates corticosterone responses to acute stressors

“…However, this again allows two possible interpretations: 1) only oCRF and rCRF were tested, which starling CRF receptors may not recognize; or 2) CRF is not an ACTH secretagog in this species. There is evidence that CRF may not be the primary ACTH secretagog in other avian species (8,33). Because no effect was found, CRF was not used in the chronic stress part of the study.…”