Ahmadzadeh A, Barnes M A, Gwazdauskas F C, Akers R M
Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061, USA.
J Dairy Sci. 2006 Jun;89(6):2051-5. doi: 10.3168/jds.S0022-0302(06)72272-X.
The role of dopamine in regulating glucocorticoid and prolactin secretion was investigated in lactating Holstein cows by characterizing serum cortisol and prolactin responses to fluphenazine, a dopamine receptor antagonist. Twelve anovulatory cows received an intravenous bolus injection of either saline (n = 6) or 0.3 mg of fluphenazine/kg of body weight (n = 6) in wk 2 postpartum. Blood samples were collected every 30 min for 4 h before and 4 h after saline or fluphenazine injection. Serum progesterone concentration was 0.13 +/- 0.1 ng/mL and did not differ between groups. No difference in serum cortisol concentrations was detected between groups before treatments. Fluphenazine increased serum cortisol concentrations within 30 min after fluphenazine administration (>30 ng/mL) and concentrations remained elevated throughout the sampling period. Cortisol remained unchanged in saline-treated cows (<10 ng/mL). Prolactin concentrations also increased after fluphenazine administration (103.1 +/- 3.1 ng/mL), but were unaffected by saline (18 +/- 3.1 ng/mL). Prolactin concentrations remained elevated throughout the sampling period in fluphenazine-treated cows. Our results indicated that a dopamine antagonist increased cortisol, suggesting that endogenous dopamine, at least in part, regulates cortisol and prolactin secretion. These effects are regulated through dopamine receptors in anovulatory lactating dairy cows during the early postpartum period.
通过描述血清皮质醇和催乳素对氟奋乃静（一种多巴胺受体拮抗剂）的反应，研究了多巴胺在调节泌乳期荷斯坦奶牛糖皮质激素和催乳素分泌中的作用。12头无排卵奶牛在产后第2周接受静脉推注生理盐水（n = 6）或0.3 mg氟奋乃静/千克体重（n = 6）。在注射生理盐水或氟奋乃静之前4小时和之后4小时，每30分钟采集一次血样。血清孕酮浓度为0.13±0.1 ng/mL，两组之间无差异。治疗前两组血清皮质醇浓度无差异。氟奋乃静给药后30分钟内血清皮质醇浓度升高（>30 ng/mL），且在整个采样期内浓度一直升高。生理盐水处理的奶牛皮质醇浓度保持不变（<10 ng/mL）。氟奋乃静给药后催乳素浓度也升高（103.1±3.1 ng/mL），但不受生理盐水影响（18±3.1 ng/mL）。在整个采样期内，氟奋乃静处理的奶牛催乳素浓度一直升高。我们的结果表明，多巴胺拮抗剂会增加皮质醇，这表明内源性多巴胺至少部分调节皮质醇和催乳素的分泌。在产后早期，这些作用通过无排卵泌乳奶牛的多巴胺受体进行调节。
