Thyrotrophin-releasing hormone-induced growth hormone secretion in ducks: Independence of peripheral plasma somatostatin, insulin, and glucagon

Harvey, S.; Foltzer-Jourdainne, Ch.; Karmann, H.; Mialhe, P

doi:10.1016/0016-6480(88)90111-6

Cited by 4 publications

(4 citation statements)

References 44 publications

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“…A period of GH unresponsiveness after TRH chal¬ lenge has also been observed in vivo in young chickens (Harvey et al 1978;Harvey, Scanes & Phillips, 1985). In rats, Carlson, Mariz & Daughaday (1974) A progressive decrease of the response of GH to TRH, parallel to the age-related decrease of basal plasma levels of GH (Foltzer, Harvey, Strosser & Mialhe, 1981) was observed, as in vivo, in adult ducks (Harvey, Foltzer-Jourdainne, Karmann & Mialhe, 1988). Similarly, TRH has little or no effect on plasma GH levels in adult chickens (Harvey, Sterling & Phillips, 1981;) and minor effects on incubated adult pituitary cells (Scanes & Gross, 1983).…”

Section: Srif Perifusionmentioning

confidence: 73%

“…The solid symbols and asterisks indicate values significantly different from the pretreatment concentrations (*/><005, **.P<001, ***P< 0-005; analysis of variance). Mialhe, 1988). TRH also stimulates GH secretion in vitro and in vivo in young chickens (Harvey, Scanes, Chadwick & Bolton, 1978;Leung & Taylor, 1983).…”

Section: Srif Perifusionmentioning

confidence: 95%

“…However, in adult ducks, GRF, TRH and SRIF have no effect on GH concentrations in peripheral plasma (Strosser et al 1985; Foltzer-Jourdainne et al 1987;Harvey, Foltzer-Jourdainne, Karmann & Mialhe, 1988). In adult chickens, the effect of GRF is much reduced and TRH stimulates GH secretion only in anaesthetized birds Scanes, Carsia, Lauterio et al 1984; .…”

Section: Introductionmentioning

confidence: 95%

“…Although specific GH-releasing factors have not been characterized in the avian hypothala¬ mus, synthetic GH-releasing factors increase plasma GH concentrations in chickens , turkeys (Proudman, 1984) and young ducks (Foltzer-Jourdainne, Harvey, Karmann & Mialhe, 1987), and hypothalamic sites regulating GH release have been detected in the ventromedial and arcuate nuclei of the domestic fowl (Rabii, Knapp, De La Guardia et al 1984). Thyrotrophin-releasing hor¬ mone (TRH) also appears to be physiologically important as a GH-releasing factor in birds, increas¬ ing the circulating GH level in young chickens Klandorf, Harvey & Fraser, 1985), ducklings (Pethes, Scanes & Rudas, 1979;Harvey, Foltzer-Jourdainne, Karmann & Mialhe, 1988) and turkey poults (Proudman, 1984). Somato¬ statin (SRIF), in contrast, has been demonstrated in the avian hypothalamus (Calas, Dubois & Assenmacher, 1975;Blahser, 1984;Foltzer, Harvey & Mialhe, 1987) and has inhibitory effects on in-vivo GH secretion in immature birds (Strosser, Harvey, Foltzer & Mialhe, 1984Harvey, Lam & Hall, 1986).…”

Section: Introductionmentioning

confidence: 99%

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In-vitro control of growth hormone secretion by synthetic releasing factors in young and adult ducks (Anas platyrhynchos)

Foltzer-Jourdainne¹,

Harvey²,

Mialhe³

1988

Journal of Endocrinology

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Release of GH from perifused duckling hemipituitaries was stimulated, in a biphasic manner, by synthetic TRH and human pancreatic GH-releasing factor (GRF). At all effective concentrations, the level of GH release was increased within 5 min of TRH or GRF perifusion and was maximal after 10 min of TRH perifusion and after 20 min of GRF perifusion. Although TRH was perifused for 20 min the level of GH release declined during the last 10 min. The most effective dose of TRH (1.0 micrograms/ml; 2.7 mumol/l) and GRF (0.5 micrograms/ml; 110 nmol/l) provoked similar (250-300%) increases in the level of GH release. However, since the effect of TRH was only of short duration, the total release of GH induced by GRF was higher than that elicited by TRH, especially with the low dose. The increase in release of GH induced by TRH or GRF was blunted when pituitaries from adult ducks were used. As in young ducks, the GH response to GRF was higher, whereas the response to TRH was very low. The GH response of perifused adult pituitaries to GRF was, however, potentiated when TRH was perifused simultaneously. The basal release of GH from both young and adult pituitary glands was unaffected by perifusion with somatostatin-14 (SRIF-14) at doses of 1 and 2 micrograms/ml. The perifusion of hemipituitary glands with similar doses of SRIF-14 was also unable to suppress the stimulation of GH release induced by prior perifusion with GRF, although when SRIF-14 and TRH were simultaneously perifused TRH-induced GH release was markedly suppressed.(ABSTRACT TRUNCATED AT 250 WORDS)

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