Dose-dependent increases in plasma growth hormone following clonidine injection in luteal phase heifers

Kuehner, L.F.; Rieger, D.; Johnson, W. H.; Walton, J.S.

doi:10.1016/0093-691x(93)90107-g

Cited by 1 publication

(2 citation statements)

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“…The nine cows given 10 pg/kg bw responded to clonidine with a GH secretory burst smaller than that reported by Kuehner et al (1993) who found peak values were ten times the basal levels. The present data are more consistent with the findings described by Gorewit (1981), although both these studies used 10-month-old heifers.…”

Section: Plasma Glucosecontrasting

confidence: 73%

“…It does, however, appear to induce a rapid and significant reduction in serum PRL levels in non-human primates (Gold et al 1978). In heifers, clonidine elicits a significant GH secretory burst at doses ranging from 5 to 30 pg/kg body weight (Gorewit 1981, Kuehner et al 1993) while pituitary PRL secretion was not affected by 20 pg/kg but was acutely stimulated by 2 pg/kg (Gorewit 1981). These findings imply a dose-dependent -2-adrenergic secretory dependence for bovine PRL.…”

Section: Introductionmentioning

confidence: 96%

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Inverse control of growth hormone and prolactin secretion in clonidine-stimulated dairy cattle

Borromeo

Berrini²,

Möller³

et al. 1995

Journal of Endocrinology

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Clonidine is a specific alpha-2-adrenoreceptor agonist that stimulates growth hormone (GH) release in animals and humans. This drug was used to study the GH and prolactin (PRL) secretory response in dairy cows and heifers. An i.v. infusion of 10 micrograms/kg body weight induced GH release to a peak concentration after 30-60 min, while 2 micrograms/kg had no effect on GH secretory patterns. Plasma PRL decreased significantly (P < 0.01) starting 15-60 min after both doses of clonidine, this effect lasting up to 6 h. Clonidine significantly lowered plasma insulin (P < 0.01) and raised plasma glucose (P < 0.01). The changes in plasma GH, PRL, insulin and glucose differed significantly between doses, the 10 micrograms/kg dose being more effective (P < 0.01). The results of our investigation in dairy cattle provide evidence of (i) an increase in GH release after 10 micrograms/kg clonidine; (ii) a concomitant decrease in PRL secretion, hence GH and PRL secretion in cattle appear inversely controlled; (iii) a significant difference between the effects of the 2 and 10 micrograms/kg doses and (iv) no relationship between the changes in plasma GH and PRL after clonidine and plasma hormone levels before treatment.

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Section: Plasma Glucosecontrasting

confidence: 73%

Section: Introductionmentioning

confidence: 96%