The Influence of Intrauterine Saline Infusion on Luteal Function and Cyclic Ovarian Activity in the Mare

Abstract

SUMMARY IU saline infusion in the mare shortened the cyclic ovulatory interval through the initiation of corpora lutea regression. The plasma progestin levels began to decrease approximately one day following the infusion and declined to < 1.0 ng/ml by 4 days post‐treatment. Six of the 10 mares responded to IU saline infusion on the 4th or 5th day postovulation with a shortened cyclic ovulatory interval of 14.8 days. The interval from saline infusion to oestrus was 6.2 days and to ovulation 10.5 days. Seven of the 10 mares responded to saline infusion on day 6 or 7 postovulation with a shortened cyclic ovulatory interval of 16.0 days. The interval from saline infusion to oestrus was 5.3 days and to ovulation 9.1 days. The three mares not responding to treatment at this time had dioestrus (midcycle) ovulations near the time of the infusion. The presence of an active corpus luteum is required for IU saline infusion to induce oestrus and to shorten the cyclic ovulatory interval. The corpora lutea, including those formed from dioestrous ovulations, must be of sufficient maturity (4 to 5 days postovulation) to be responsive to the lytic effects of IU saline infusion. RÉSUMÉ En provoquant une régression du corps jaune l'injection intra utérine d'une solution saline a d'une manière générale raccourci la durée des cycles ovulatoires. Les taux plasmatiques de Progestin ont commencé de décroitre environ 1 jour après l'administration pour atteindre un taux infèrieur à 1.0 mg/ml 4 jours plus tard. Six des dix juments traitées montrèrent une réponse à l'irrigation vers le 4° ou le 5° jour suivant l'ovulation avec un intervalle cyclique entre deux ovulations de 14.8 jours. L'intervalle entre l'injection saline et l'apparition des chaleurs fut de 6.2 jours et entre l'injection et l'ovulation de 10.5 jours. Pour sept juments sur dix lorsque l'injection intra utérine était pratiquée vers le 6° ou le 7° jour suivant l'ovulation l'intervalle entre deux cycles était de 16.0 jours. L'intervalle entre l'irrigation et l'apparition de l'oestrus était alors de 5.3 jours, entre l'irrigation et l'ovulation de 9.1 jours. Les trois juments réfractaires étaient en dioestrus lors de l'irrigation. La présence d'un corps jaune en activité est nécessaire pour que l'irrigation saline puisse réduire l'oestrus et raccourcir le cycle ovulatoire. Le corps jaune doit avoir une maturité suffisante (4 ou 5 jours après l'ovulation) pour subir l'action lytique de l'irrigation saline. ZUSAMMENFASSUNG Die intrauterine Infusion von physiologischer Kochsalzlösung verkürzte das zyklische Ovulationsintervall durch die Beschleunigung der Gelbkörperregression. Die Plasma‐Progestinspiegel begannen ungefähr einen Tag nach der Infusion abzufallen bis auf <1.0 mg/ml am 4. Tag nach der Behandlung. Sechs der zehn Stuten beantworteten die Infusion am 4. oder 5. Tag nach der Ovulation mit einem verkürzten Zyklus von 14.8 Tagen. Das Intervall zwischen Infusion und Oestrus betrug 6.2 Tage, zwischen Infusion und Ovulation 10.5 Tage. Sieben der zehn Stuten, denen die Kochsalz...

The effect of exogenous oxytocin on luteal function in mares

“…2b) was probably due to the presence of a dioestrous ovulation (Neely et al, 1975) on Day 14 of the cycle, which prolonged the luteal phase for approximately another 5 days before complete luteal regression (<l-0 ng progestagen/ml) occurred. Similarly, the 28-day post-treatment cycle in Mare 1 (Text- fig.…”

“…3) (Stabenfeldt, Hughes, Evans & Neely, 1974). On Day 41 of this prolonged luteal phase, the mare was given an intrauterine infusion of 250 ml physiological saline (0-54 M-NaCl) (Neely et al, 1975) resulting in luteolysis with ovulation occurring on Day 46. Uterine tone in these 3 mares remained unchanged during the hour after oxytocin injection.…”

“…Days 4-9 (Day 0 = ovulation) (Arthur, 1970;Neely et al, 1975;Douglas & Ginther, 1972;Allen & Rowson, 1973). Experiment I.…”

“…Luteolysis occurs with doses of prostaglandin (PG) F-2a as low as 1-25 mg (Douglas & Ginther, 1972), although 30 mg PGF-2a are needed to induce luteolysis in cows (Oxender, Noden, Louis & Hafs, 1974). Mares also respond with luteolysis after intrauterine infusion of normal saline, a non-irritating substance (Arthur, 1970(Arthur, , 1975Neely, Hughes, Stabenfeldt & Evans, 1975), while in cows and sheep, foreign bodies or irritating substances have to be placed in the uterus to cause a luteolytic response (Moore & Nalbandov, 1953;Yamauchi, Nakahara, Keneda & Inui, 1967;Nakahara, Domeki & Yamauchi, 1971;Sequin, Morrow & Oxender, 1974). It might, therefore, be expected that the mare would respond to the luteolytic effects of oxytocin as demonstrated for cattle (Armstrong & Hansel, 1959), possibly via the ability of oxytocin to release PGF-2a as in the ewe (Sharma & Fitzpatrick, 1974).…”

Desenvolvimento de um método de microlavagem para estudo do microambiente uterino em bovinos: efeitos na função luteínica, crescimento folicular e manutenção da prenhez inicial

“…Meyer et al (1995) Hurtgem e Whitmore (1978) estudando biopsia uterina em éguas no 4º dia do diestro observaram uma diminuição da concentração plasmática de P 4 24 a 48 hr após a manipulação do endométrio e uma diminuição da duração do ciclo estral em relação ao grupo controle. Neely et al (1975) infundiram 500mL solução salina intra uterina nos dias 12, 13, 14 do diestro em éguas, através de uma sonda de lavagem intra uterina e observaram a duração da do ciclo estral, a conclusão do trabalho é que não houve diminuição da duração do ciclo estral em relação ao grupo controle, já Neely et al (1975) por infusão intra-uterina de solução salina nos dias 4 ou 5 e 6 ou 7 do diestro em éguas, observaram uma diminuição da concentração plasmática de P 4 e luteolise precoce nessas éguas em relação ao grupo controle. Handler et al (2003) estudaram os padrões de ocitocina, metabolito da PGF2α e concentrações de P 4 no plasma sanguíneo de éguas submetidas apenas a uma inserção de cateter na cérvice e a uma dilatação do balloon do cateter na cérvice nos dias 5 e 7 do diestro.…”