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Relative transcript abundance of oxytocin receptor gene in porcine uterus during luteolysis and early pregnancy

100%

Oponowicz A., Franczak A., Kurowicka B., Kotwica G.

Journal of Applied Genetics

2006

vol. 47

issue 4

345-351

The aim of the present study was to investigate transcript localization of the oxytocin receptor (OTR) gene in different cells of the porcine uterus during luteolysis and early pregnancy (days 14?16) using in situ hybridization (ISH). OTR mRNA was localized in the uterine luminal epithelium (LEC), glandular epithelium (GEC), stromal cells (SC) of the endometrium, in the longitudinal muscle layer (LM) and circular muscle layer (CM) of the myometrium. The OTR transcript was quantified by optical density units of silver grains. The OTR transcript levels in the endometrium and myometrium were statistically higher during luteolysis than during early pregnancy (P < 0.05). Besides, during luteolysis, the mRNA level was higher in the LEC, GEC of the endometrium and LM of the myometrium compared to that observed in the SC of endometrium and CM of the myometrium, respectively (P < 0.05). In summary: 1) the level of OTR mRNA in uterine tissues is higher during luteolysis compared to early pregnancy, 2) the OTR transcript level in endometrial cells did not correspond to the sensitivity of these cells to oxytocin (OT), 3) the myometrial expression of the OTR gene is appropriate to control contractile activity and secretion of PG during luteolysis.

The central oxytocin pulse generator: a pacemaker for the ovarian cycle

72%

McCracken J. A., Custer E. E., Eldering J. A., Robinson A. G.

Acta Neurobiologiae Experimentalis

1996

vol. 56

issue 3

819-832

During luteolysis in sheep, episodic pulses of oxitocin (OT), contributed by the neurophysis and the corpus luteum (CL), stimulate uterine luteolytic pulses of prostaglandin (PG) F2alpha via endometrial OT receptors.To distinquish relative contributions of neurophysical and luteal OT, overoctomized sheep were given estradiol-17 beta (E) and progeterone (P) to simulate levelas during the cycle.In intact sheep, luteectomy was performed to exclude the CL as a source of OT and initiate P withdrawal.IN overiectomized sheep, E (mug/h for 12 to 36h) superimposed on basal E (0.05 mug/h) caused a series of 4 to 6 episodes of high frequency pulses of OT, each episode lasting 1 to 2 h at intervals of 3 h, and commencing at 24 h.Withdrawal of P (500 mug/h), superimposed on basal E in ovariectomized sheep, oe luteectomy in intact sheep, evoked similar episodes of high frequency pulses of OT begining at 24h.We conclude that (1) an increase in E levels, or the return of E actin following P withdrawal, causes intermittent increases in tyhe frequency of the central OT pulse generator, (2) high frequency pulses of OT initiate subluteolytic levels of uterine PGF2 alpha which trigger a supplemental release of luteal OT; (3) luteal OT amplifies the secretion of uterine PGF2 alpha which initiates luteolysis and causes more luteal OT to be secreted; and (4) in addition to the established hypothalmic-antrior pituitarty-gonadal axis for initiating the ovarian cycle (via the gonadotrophins), there is now evidence for a hypothalmic-posterior pituitary-gonadal axis for terminating the ovarian cycle (via OT).

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1 Acta Neurobiologiae Experimentalis

1 Journal of Applied Genetics

1 2006

1 1996

1 Custer E. E.

1 Eldering J. A.

1 Franczak A.

1 Kotwica G.

1 Kurowicka B.

1 McCracken J. A.

1 Oponowicz A.

1 Robinson A. G.

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Relative transcript abundance of oxytocin receptor gene in porcine uterus during luteolysis and early pregnancy

The central oxytocin pulse generator: a pacemaker for the ovarian cycle