Abstract
Four studies were conducted to evaluate the effects of several physiologic and pharmacologic agents on serum prolactin concentrations in the nonpregnant mare. An increase in prolactin measured in response to administration of thyrotropin-releasing hormone (TRH; 50 micrograms, iv) was found not to vary (P = .20) in mares in estrus compared with mares in diestrus (5 to 10 d post-ovulation). Administration in the dopamine receptor blocker, metoclopramide (25 or 100 mg, im), rapidly increased serum prolactin, and the response was dependent on dose administered (total prolactin measured for 420 min was 3,362.7 +/- 182.1 ng for 25 mg, and 4,485.7 +/- 212.6 ng for 100 mg administered im; P less than .05), but not on route of injection (3,026.3 +/- 492.3 ng prolactin with 25 mg, iv; P less than .05). Similarly, sulpiride, a D-2 dopamine receptor blocker, induced an increase in serum prolactin, which appeared to be maximal at a dose of 25 mg (6,556.3 +/- 636.9 ng prolactin/420 min compared with 6,594.5 +/- 169.3 ng prolactin/420 min with 100 mg sulpiride; P less than .10). Finally, bromocriptine, a dopamine agonist, decreased serum prolactin compared with vehicle-injected controls, but the inhibitory effect was found only when basal levels of serum prolactin were highest (in May). These data suggest that mechanisms controlling prolactin secretion in the mare are similar to those described in other mammalian species, and that the seasonal decline in serum prolactin is not the result of increased sensitivity to the proposed prolactin-inhibiting factor, dopamine.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1292-1297 |
| Number of pages | 6 |
| Journal | Journal of Animal Science |
| Volume | 65 |
| Issue number | 5 |
| DOIs | |
| State | Published - Jan 1 1987 |
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All Science Journal Classification (ASJC) codes
- Food Science
- Animal Science and Zoology
- Genetics
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Effects of physiologic and pharmacologic agents on serum prolactin concentrations in the nonpregnant mare. / Johnson, Alan Leslie; Becker, S. E.
In: Journal of Animal Science, Vol. 65, No. 5, 01.01.1987, p. 1292-1297.Research output: Contribution to journal › Article
TY - JOUR
T1 - Effects of physiologic and pharmacologic agents on serum prolactin concentrations in the nonpregnant mare.
AU - Johnson, Alan Leslie
AU - Becker, S. E.
PY - 1987/1/1
Y1 - 1987/1/1
N2 - Four studies were conducted to evaluate the effects of several physiologic and pharmacologic agents on serum prolactin concentrations in the nonpregnant mare. An increase in prolactin measured in response to administration of thyrotropin-releasing hormone (TRH; 50 micrograms, iv) was found not to vary (P = .20) in mares in estrus compared with mares in diestrus (5 to 10 d post-ovulation). Administration in the dopamine receptor blocker, metoclopramide (25 or 100 mg, im), rapidly increased serum prolactin, and the response was dependent on dose administered (total prolactin measured for 420 min was 3,362.7 +/- 182.1 ng for 25 mg, and 4,485.7 +/- 212.6 ng for 100 mg administered im; P less than .05), but not on route of injection (3,026.3 +/- 492.3 ng prolactin with 25 mg, iv; P less than .05). Similarly, sulpiride, a D-2 dopamine receptor blocker, induced an increase in serum prolactin, which appeared to be maximal at a dose of 25 mg (6,556.3 +/- 636.9 ng prolactin/420 min compared with 6,594.5 +/- 169.3 ng prolactin/420 min with 100 mg sulpiride; P less than .10). Finally, bromocriptine, a dopamine agonist, decreased serum prolactin compared with vehicle-injected controls, but the inhibitory effect was found only when basal levels of serum prolactin were highest (in May). These data suggest that mechanisms controlling prolactin secretion in the mare are similar to those described in other mammalian species, and that the seasonal decline in serum prolactin is not the result of increased sensitivity to the proposed prolactin-inhibiting factor, dopamine.
AB - Four studies were conducted to evaluate the effects of several physiologic and pharmacologic agents on serum prolactin concentrations in the nonpregnant mare. An increase in prolactin measured in response to administration of thyrotropin-releasing hormone (TRH; 50 micrograms, iv) was found not to vary (P = .20) in mares in estrus compared with mares in diestrus (5 to 10 d post-ovulation). Administration in the dopamine receptor blocker, metoclopramide (25 or 100 mg, im), rapidly increased serum prolactin, and the response was dependent on dose administered (total prolactin measured for 420 min was 3,362.7 +/- 182.1 ng for 25 mg, and 4,485.7 +/- 212.6 ng for 100 mg administered im; P less than .05), but not on route of injection (3,026.3 +/- 492.3 ng prolactin with 25 mg, iv; P less than .05). Similarly, sulpiride, a D-2 dopamine receptor blocker, induced an increase in serum prolactin, which appeared to be maximal at a dose of 25 mg (6,556.3 +/- 636.9 ng prolactin/420 min compared with 6,594.5 +/- 169.3 ng prolactin/420 min with 100 mg sulpiride; P less than .10). Finally, bromocriptine, a dopamine agonist, decreased serum prolactin compared with vehicle-injected controls, but the inhibitory effect was found only when basal levels of serum prolactin were highest (in May). These data suggest that mechanisms controlling prolactin secretion in the mare are similar to those described in other mammalian species, and that the seasonal decline in serum prolactin is not the result of increased sensitivity to the proposed prolactin-inhibiting factor, dopamine.
UR - http://www.scopus.com/inward/record.url?scp=0023441633&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0023441633&partnerID=8YFLogxK
U2 - 10.2527/jas1987.6551292x
DO - 10.2527/jas1987.6551292x
M3 - Article
C2 - 3121569
AN - SCOPUS:0023441633
VL - 65
SP - 1292
EP - 1297
JO - Journal of Animal Science
JF - Journal of Animal Science
SN - 0021-8812
IS - 5
ER -