Plasma progesterone and LH concentrations in ewes after injection of an analogue of prostaglandin F-2 

Abstract

Plasma progesterone and LH concentrations were monitored throughout a natural oestrous cycle in 12 Clun Forest ewes and compared to those following treatment with a single i.m. injection of 100 microng ICI 80,996, an analogoue of prostaglandin F-2alpha, given during the luteal phase of the cycle. After injection of the analogue there was a high degree of synchrony in the return of oestrus (440 +/- 1-9 h; mean +/- S.E.M.) and the timing of the LH peak (48-5 +/- 2-0 h) from injection. There were no significant differences in the plasma progesterone concentrations or in the height and duration of the preovulatory LH peak between control and treatment cycles. The technique offers the possibility of controlled ovulation in the ewe.

Response of ewes to a single injection of an analogue of PGF-2 given at different stages of the oestrous cycle

“…The overall mean interval of 37-7 ± 1-6 h between injection of ICI 80,996 and onset of oestrus recorded in this study was significantly (P < 0-05) shorter than that of 44-0 ± 1-9 h observed in a previous study (Acritopoulou et al, 1977). However, no significant difference could be demonstrated between the two studies in the timing of the LH peak in relation to injection of ICI 80,996 (45-3 ± 3-2 h and 48-5 ± 2-0 h respectively).…”

“…(<0-5 ng/ml) by 24 h after injection, and there was a pronounced LH release at the induced oestrus (see Table 1). (Acritopoulou et al, 1977) and with similar findings in cattle (Louis, Hafs & Morrow, 1974 (Acritopoulou et al, 1977).…”

“…injection of 100 µg of the PGF-2a analogue, ICI 80,996, given to ewes between Days 5 and 8 of the oestrous cycle, caused rapid luteolysis and resulted in well synchronized behavioural oestrus (Acritopoulou, Haresign, Foster & Lamming, 1977), but response to treat¬ ment at other stages of the cycle was not studied. The Plasma progesterone concentrations were measured in the 2 h (10 ml) and daily samples by the radioimmunoassay described by Haresign, Foster, Haynes, Crighton & Lamming (1975).…”

Ovarian follicular dynamics in Suffolk ewes at different periods of the year

“…The recruitment of the follicle(s) destined to ovulate took place on day 14 of the cycle which coincides with luteolysis and it is similar to the pattern described in women (Nillson et al, 1982), monkeys (Goodman and Hodgen, 1979) and sheep (Smeaton and Robertson, 1971;Acritopoulou et al, 1977). In contrast, recruitment occurs at the time of the previous ovulation in rats (Hirschfield and Midgley, 1978), and it occurs during the late luteal phase in mares (Driancourt and Palmer, 1984 (Driancourt et al, 1985(Driancourt et al, , 1986.…”

Respostas endócrinas e ovarianas associadas com o folículo dominante da primeira onda folicular em ovelhas sincronizadas com CIDR ou PGF2alfa

“…Depois do dia 11, as duas medidas começaram a decrescer, mas o declínio de P 4 foi mais acentuado, quando comparado com o diâmetro do corpo lúteo. Acritopoulou et al (1977), comparando um grupo de ovelhas sincronizadas com uma injeção de PGF 2α (100 mg) e outro grupo em condições naturais, não observaram diferenças na concentração plasmática de P 4 durante os períodos de pré e pós-tratamento. Depois da injeção de cloprostenol, um análogo sintético de PGF 2α , em ovelhas Finn-Merino, Campbell et al (1990) notaram que as secreções de E 2 e de androstenediona elevaram-se nas quatro ou oito horas seguintes.…”