Secretion of dopamine and norepinephrine in hypophyseal portal blood and prolactin in peripheral blood of Holstein cattle

The objective was to test the hypothesis that dopamine regulates prolactin (PRL) secretion by determining acute changes in catecholamine concentrations in hypophyseal portal blood of cattle, and their relation to peripheral blood concentration of PRL in hypophyseal stalk-transected (HST) and sham-op...

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Bibliographic Details
Published in:Domestic animal endocrinology 2001-02, Vol.20 (2), p.89-100
Main Authors: Hard, D.L., Bhatnagar, R.K., Molina, J.R., Anderson, L.L.
Format: Article
Language:English
Subjects:
Animals
Cattle - physiology
Dopamine - blood
Dopamine - secretion
Female
Kinetics
Norepinephrine - blood
Norepinephrine - secretion
Pituitary Gland - blood supply
Pituitary Gland - physiology
Pituitary Gland - surgery
Portal System
Prolactin - blood
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Summary:The objective was to test the hypothesis that dopamine regulates prolactin (PRL) secretion by determining acute changes in catecholamine concentrations in hypophyseal portal blood of cattle, and their relation to peripheral blood concentration of PRL in hypophyseal stalk-transected (HST) and sham-operated controls (SOC). Holstein heifers (606 ± 21 kg BW; mean ± SE) were subjected to neurosurgery for 8 h to collect hypophyseal portal blood with a stainless steel cannula designed with a cuff placed under the pituitary stalk and peripheral blood via a jugular vein catheter. PRL plasma concentration was measured by radioimmunoassay, and dopamine and norepinephrine in portal plasma by radioenzymatic assay. During anesthesia before HST or SOC, PRL plasma concentration ranged from 20–40 ng/ml throughout 255 min. PRL abruptly increased and remained above 90 ng/ml after HST compared with a steady decrease to 8 ng/ml) was significantly increased ( P < 0.05) compared with peripheral blood (
ISSN:0739-7240
1879-0054
DOI:10.1016/S0739-7240(01)00085-6