Khalid, M., Ijaz, A., Haresign, W. (1999). RESPONSE OF LH TO LONG-TERM PULSATILE AND CONTINUOUS INFUSIONS OF GNRH IN OVARIECTOMIZED, ESTRADIOL -17 B IMPLANTED EWES DURING SEASONAL ANOESTROUS. test, 41.1(81), 253-264. doi: 10.21608/avmj.1999.182531
M. Khalid; A. Ijaz; W. Haresign. "RESPONSE OF LH TO LONG-TERM PULSATILE AND CONTINUOUS INFUSIONS OF GNRH IN OVARIECTOMIZED, ESTRADIOL -17 B IMPLANTED EWES DURING SEASONAL ANOESTROUS". test, 41.1, 81, 1999, 253-264. doi: 10.21608/avmj.1999.182531
Khalid, M., Ijaz, A., Haresign, W. (1999). 'RESPONSE OF LH TO LONG-TERM PULSATILE AND CONTINUOUS INFUSIONS OF GNRH IN OVARIECTOMIZED, ESTRADIOL -17 B IMPLANTED EWES DURING SEASONAL ANOESTROUS', test, 41.1(81), pp. 253-264. doi: 10.21608/avmj.1999.182531
Khalid, M., Ijaz, A., Haresign, W. RESPONSE OF LH TO LONG-TERM PULSATILE AND CONTINUOUS INFUSIONS OF GNRH IN OVARIECTOMIZED, ESTRADIOL -17 B IMPLANTED EWES DURING SEASONAL ANOESTROUS. test, 1999; 41.1(81): 253-264. doi: 10.21608/avmj.1999.182531

RESPONSE OF LH TO LONG-TERM PULSATILE AND CONTINUOUS INFUSIONS OF GNRH IN OVARIECTOMIZED, ESTRADIOL -17 B IMPLANTED EWES DURING SEASONAL ANOESTROUS

Assiut Veterinary Medical Journal
Article 21, Volume 41.1, Issue 81, April 1999, Pages 253-264    PDF (2.87 M)
Document Type: Research article
DOI: 10.21608/avmj.1999.182531
Authors
M. Khalid1; A. Ijaz2; W. Haresign1
1Animal Sciences Group, Welsh Institute of Rural Studies, Univ. of Wales Aberystwyth, Lianbodarn Campus, Aberystwyth, SY 233 AL,
2Dept. of Vet., Clinical Sciences, Jordan Univ. of Science and Technology, P.O. Box 3030, Irbid, Jordan
Abstract
Pituitary LH responses to long-term pulsatile and continuous infusion of GnRH were monitored in estradiol-17 B-implanted ovariectomized ewes during seasonal anoestrous (April and May). The experiment was performed in 2 replicates (8 ewes per replicate). Half of the animals in each replicate were infused continuously with GnRH (175 ng/h), while the other half were given a pulsatile injection of 350 ng GnRH every 2 h for a period of 20 days. GnRH administration was carried out via indwelling jugular vein catheter. Blood samples for LH determination were collected at 15-min intervals, from 6 h before until 24 h after the start of treatment, and then at 8- h intervals on days 3, 6, 10, 15, and 20 of the treatment. The 8-h bleed on day 20 was immediately followed by a 12-h bleed once the treatment had ended. Before the start of GnRH treatment, plasma LH concentrations rose immediately in infused animals. However, after an initial significant elevation on day 1, LH values were not different from mean pre-treatment concentrations for the rest of the treatment period. In contrast, injected ewes (350 ng GnRH) responded to each GnRH injection throughout the 20-day treatment period. The results suggested that the pituitary gland remains responsive to pulsatile but not to continuous GnRH administration for longer time periods
Keywords
Key Words: LH GNRH Ewes Anoestrous
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