LongeCity - Drugs that influence cortisol

Dopamine Antagonist Alters Serum Cortisol and Prolactin Secretion in Lactating Holstein Cows

A. Ahmadzadeh[sup]1[/sup][sup],<a href="http://jds.fass.org/cgi/content/full/89/6/2051#FN1">2[/sup], M. A. Barnes, F. C. Gwazdauskas and R. M. Akers Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061

The role of dopamine in regulating glucocorticoid and prolactin[sup] [/sup]secretion was investigated in lactating Holstein cows by characterizing[sup] [/sup]serum cortisol and prolactin responses to fluphenazine, a dopamine[sup] [/sup]receptor antagonist. Twelve anovulatory cows received an intravenous[sup] [/sup]bolus injection of either saline (n = 6) or 0.3 mg of fluphenazine/kg[sup] [/sup]of body weight (n = 6) in wk 2 postpartum. Blood samples were[sup] [/sup]collected every 30 min for 4 h before and 4 h after saline or[sup] [/sup]fluphenazine injection. Serum progesterone concentration was[sup] [/sup]0.13 ± 0.1 ng/mL and did not differ between groups. No[sup] [/sup]difference in serum cortisol concentrations was detected between[sup] [/sup]groups before treatments. Fluphenazine increased serum cortisol[sup] [/sup]concentrations within 30 min after fluphenazine administration[sup] [/sup](>30 ng/mL) and concentrations remained elevated throughout[sup] [/sup]the sampling period. Cortisol remained unchanged in saline-treated[sup] [/sup]cows (<10 ng/mL). Prolactin concentrations also increased[sup] [/sup]after fluphenazine administration (103.1 ± 3.1 ng/mL),[sup] [/sup]but were unaffected by saline (18 ± 3.1 ng/mL). Prolactin[sup] [/sup]concentrations remained elevated throughout the sampling period[sup] [/sup]in fluphenazine-treated cows. Our results indicated that a dopamine[sup] [/sup]antagonist increased cortisol, suggesting that endogenous dopamine,[sup] [/sup]at least in part, regulates cortisol and prolactin secretion.[sup] [/sup]These effects are regulated through dopamine receptors in anovulatory[sup] [/sup]lactating dairy cows during the early postpartum period.

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