Relationship between Hypothalamic Serotoninergic Activity and Prolactin and Growth Hormone Secretion in the Domestic Cockerel

Hall, T.R.; Harvey, S.; Chadwick, A.

doi:10.1159/000123981

Cited by 14 publications

(5 citation statements)

References 18 publications

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“…Three-week-old birds were too small for serial blood sampling, and so the older (6 week) birds were used when temporal comparisons were made. At 18 weeks cockerels are approaching pubescence when neuroendocrine mechanisms may be maturing (Sharp & Gow, 1983) and differences in responses may be seen, as was found with prolactin and growth hormone secretion (Hall, Harvey & Chadwick, 1984). Experiment 1 Six-week-old cockerels were injected with 10 mg quipazine maleate/kg (Miles Labs Inc., Elkhart, IN, U.S.A.), a specific serotonin receptor agonist, 80 mg pargyline HCl/kg (Sigma Chemical Co., Poole, Dorset), an inhibitor of serotonin breakdown or 0-9% (w/v) NaCl and plasma was collected 15, 30,45 and 60 min later.…”

Section: Methodsmentioning

confidence: 90%

“…Different populations of seroto¬ nin receptors may regulate different hypothalamic functions, since both methysergide and cyprohepta¬ dine block prolactin responses to quipazine whereas cyproheptadine, but not methysergide, blocks growth hormone responses to quipazine Hall, Chadwick & Harvey, 1983). Plasma LH concen¬ trations are also reduced following inhibition of MAO, which increases hypothalamic serotonin con¬ centrations (El Halawani et al 1978Hall et al 1984). Blockade of MAO also increases avian hypo¬ thalamic catecholamine concentrations (El Halawani et al 1978 but this effect is only temporary, whereas serotonin is chronically increased Hall, Chadwick, Woodhouse & Harvey, 1985) and plasma LH remains depressed for at least 8 h. The specificity of serotoninergic inhibition of LH secretion in cockerels is shown by the response to L-tryptophan, which selectively activates serotoninergic neurones (Curzon, 1981).…”

Section: Discussionmentioning

confidence: 99%

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Serotoninergic inhibition of LH secretion in the domestic fowl

Hall¹,

Cheung²,

Harvey³

1986

Journal of Endocrinology

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Immature cockerels were injected with drugs known to affect serotoninergic activity. The receptor agonist quipazine as well as pargyline, an inhibitor of serotonin breakdown, both reduced plasma LH concentrations in a time-dependent fashion. The effect of pargyline was also dose-related. The serotonin precursor, tryptophan, reduced plasma LH levels. Tryptophan and pargyline were as effective in pubertal cockerels as in 3-week-old birds. Responses to quipazine were attenuated by the antagonist, methysergide, although another antagonist, cyproheptadine, also reduced plasma LH levels. Serotonin itself had no effect on plasma LH levels. Parachlorophenylalanine, which blocks serotonin synthesis, had no effect on plasma LH by itself, but attenuated the tryptophan-induced inhibition of LH. These data indicate that serotoninergic mechanisms inhibit secretion of LH in domestic fowl. This mechanism probably operates through the central nervous system.

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Section: Methodsmentioning

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Serotoninergic inhibition of LH secretion in the domestic fowl

Hall¹,

Cheung²,

Harvey³

1986

Journal of Endocrinology

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show abstract

“…Previous animal experiments revealed no direct effect of serotonin on basal GH secretion (Kato et al, 1980;Hail, 1982;Hall et al, 1984). With a histochemical technique, synaptic connections between serotonergic nerve endings and somatostatin neurons have been observed in the rat anterior periventricular nucleus (Kiss et al, 1988).…”

Section: Discussionmentioning

confidence: 94%

The Combination Therapy with Bromocriptine and Cyproheptadine in Patients with Acromegaly.

et al. 1989

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The therapeutic efficacy of the combination of cyproheptadine and bromocriptine was studied in 15 patients with active acromegaly showing incomplete GH suppression in response to bromocriptine therapy alone. The mean basal plasma GH was 31.3 +/- 5.5 micrograms/L, and it decreased to 19.0 +/- 3.9 micrograms/L during the single bromocriptine therapy (10 to 20 mg for 2 to 21 months). When cyproheptadine (12 to 16 mg for 8 to 52 months) was added to bromocriptine therapy, plasma GH decreased further (9.4 +/- 3.0 micrograms/L: vs pretreatment, P less than 0.001; vs bromocriptine treatment, P less than 0.005), and GH normalization was obtained in 8 patients. The plasma somatomedin-C levels in these 8 patients (0.3-1.8 U/ml) were within the normal range during the combination therapy. Plasma GH responses to TRH or GHRH were markedly suppressed in 6 patients during the combination therapy compared to pretreatment or during bromocriptine treatment. In addition, a clear reduction in the tumor size was observed in 4 of 7 previously untreated patients during the combination therapy. In conclusion, cyproheptadine has therapeutic efficacy in acromegalic patients who showed incomplete GH suppression in response to treatment with bromocriptine alone. Following the cyproheptadine and bromocriptine combination therapy tumor shrinkage was observed in some patients.

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“…The administration of serotonin, its receptor agonist quipazine (Hong & Pardo, 1966), or pargyline HC1, a monoamine oxidase inhibitor that increases hypo¬ thalamic serotonin concentrations (Hall, Harvey & Chadwick, 1984), all produced increases in circulating corticosterone concentrations in young cockerels, although the hormone effects were short-lived (Figs 1 and 5). The quipazine-induced response was attenu¬ ated by cyproheptadine, a serotonin antagonist.…”

Section: Discussionmentioning

confidence: 99%

Serotoninergic regulation of corticosterone secretion in domestic fowl

Cheung¹,

Hall²,

Harvey³

1987

Journal of Endocrinology

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The effects of serotoninergic drugs on adrenocortical function in domestic fowl were examined. Administration of the serotonin receptor agonist 2-(1-piperazinyl)quinoline maleate (quipazine), an inhibitor of serotonin metabolism, N-methyl-N-2-propynylbenzylamine HCl (pargyline), as well as serotonin itself, all increased plasma concentrations of corticosterone. The maximum responses to serotonin and quipazine occurred 1 h after treatment. The quipazine-stimulated response was partly prevented by the serotonin antagonist cyproheptadine. Cockerels pretreated with dexamethasone, a synthetic steroid known to inhibit pituitary ACTH release, showed attenuated responses to subsequent quipazine, pargyline or serotonin injection. Serotonin, quipazine and cyproheptadine did not affect corticosterone release directly from the adrenal gland incubated in vitro, nor did they affect adrenal responsiveness to ACTH stimulation. The neurotoxin 5,6-dihydroxytryptamine injected into day-old chicks decreased plasma concentrations of corticosterone for up to 7 days after treatment, with corresponding decreases in the hypothalamic concentration of serotonin, but not dopamine or noradrenaline concentrations. These results show that adrenal corticosterone secretion is regulated by a central serotoninergic system, probably acting on the hypothalamo-pituitary-adrenal axis.

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Relationship between Hypothalamic Serotoninergic Activity and Prolactin and Growth Hormone Secretion in the Domestic Cockerel

Cited by 14 publications

References 18 publications

Serotoninergic inhibition of LH secretion in the domestic fowl

Serotoninergic inhibition of LH secretion in the domestic fowl

The Combination Therapy with Bromocriptine and Cyproheptadine in Patients with Acromegaly.

Serotoninergic regulation of corticosterone secretion in domestic fowl

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