TY - JOUR
T1 - Effects of estrogen and progesterone on serum prolactin and luteinizing hormone levels in ovariectomized turkeys (Meleagris gallopavo)
AU - El Halawani, M. E.
AU - Silsby, J. L.
AU - Fehrer, S. C.
AU - Behnke, E. J.
PY - 1983/10
Y1 - 1983/10
N2 - Serum prolactin (PRL) and luteinizing hormone (LH) levels from mature female turkeys were determined following ovariectomy and daily subcutaneous injections for 4 or 9 days of 0.002-2.0 mg/kg estradiol benzoate (EB), 0.05-2.0 mg/kg progesterone (P), or their combinations. Serum PRL levels were increased (P < 0.05) at the onset of sexual maturity in intact controls, but not in ovariectomized turkeys. Injection of 0.02 mg/kg EB into ovariectomized turkeys resulted in elevated (P < 0.05) serum PRL levels after 8 treatment days. Higher doses failed to elicit a response of greater magnitude. EB at doses of 0.02-2.0 mg/kg reduced LH levels while 0.002 mg/kg EB increased LH levels above (P < 0.05) those of ovariectomized controls. The 1.0-mg/kg P dose increased (P < 0.05) serum PRL within 24-48 hr of administration while the 0.05-, 0.5-, or 2.0-mg/kg P doses failed to elicit a response. When P was injected in doses of 0.5-2.0 mg/kg, LH levels were decreased in a dose-response manner. The injection of EB combined with P had a variable effect on serum PRL levels. The 0.5- or 1.0-mg/kg dose of P facilitated (advanced in time) the rise in serum PRL level induced by 0.02 mg/kg of EB. In contrast, the positive feedback effect of 0.2 mg/kg of EB was blocked when administered with 0.5 mg/kg of P. Serum LH levels were dramatically decreased by all steroid combinations used. These results indicate that daily injections of EB and/or P in ovariectomized turkeys have a variable effect on serum PRL and LH levels depending upon the dose, the duration of treatment, or the ratio between EB and P.
AB - Serum prolactin (PRL) and luteinizing hormone (LH) levels from mature female turkeys were determined following ovariectomy and daily subcutaneous injections for 4 or 9 days of 0.002-2.0 mg/kg estradiol benzoate (EB), 0.05-2.0 mg/kg progesterone (P), or their combinations. Serum PRL levels were increased (P < 0.05) at the onset of sexual maturity in intact controls, but not in ovariectomized turkeys. Injection of 0.02 mg/kg EB into ovariectomized turkeys resulted in elevated (P < 0.05) serum PRL levels after 8 treatment days. Higher doses failed to elicit a response of greater magnitude. EB at doses of 0.02-2.0 mg/kg reduced LH levels while 0.002 mg/kg EB increased LH levels above (P < 0.05) those of ovariectomized controls. The 1.0-mg/kg P dose increased (P < 0.05) serum PRL within 24-48 hr of administration while the 0.05-, 0.5-, or 2.0-mg/kg P doses failed to elicit a response. When P was injected in doses of 0.5-2.0 mg/kg, LH levels were decreased in a dose-response manner. The injection of EB combined with P had a variable effect on serum PRL levels. The 0.5- or 1.0-mg/kg dose of P facilitated (advanced in time) the rise in serum PRL level induced by 0.02 mg/kg of EB. In contrast, the positive feedback effect of 0.2 mg/kg of EB was blocked when administered with 0.5 mg/kg of P. Serum LH levels were dramatically decreased by all steroid combinations used. These results indicate that daily injections of EB and/or P in ovariectomized turkeys have a variable effect on serum PRL and LH levels depending upon the dose, the duration of treatment, or the ratio between EB and P.
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U2 - 10.1016/0016-6480(83)90159-4
DO - 10.1016/0016-6480(83)90159-4
M3 - Article
C2 - 6628980
AN - SCOPUS:0021039460
SN - 0016-6480
VL - 52
SP - 67
EP - 78
JO - General and Comparative Endocrinology
JF - General and Comparative Endocrinology
IS - 1
ER -