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International Journal of Endocrinology
Volume 2017, Article ID 4357080, 9 pages
Research Article

Muscarinic Receptors Types 1 and 2 in the Preoptic-Anterior Hypothalamic Areas Regulate Ovulation Unequally in the Rat Oestrous Cycle

1Laboratory of Neuroendocrinology, Biology of Reproduction Research Unit, Facultad de Estudios Superiores Zaragoza, UNAM, Mexico City, Mexico
2Department of Basic Research, National Institute of Geriatrics, Mexico City, Mexico
3Division of Endocrinology, Department of Medicine, Albert Einstein College of Medicine, Bronx, New York City, NY, USA

Correspondence should be addressed to María Esther Cruz; xm.moc.oohay@yolbcem

Received 20 November 2016; Accepted 6 February 2017; Published 15 March 2017

Academic Editor: Michael Horowitz

Copyright © 2017 Yadira L. López-Ramírez et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Muscarinic receptors types 1 (m1AChR) and 2 (m2AChR) in the preoptic and anterior hypothalamus areas (POA-AHA) were counted, and the effects of blocking these receptors on spontaneous ovulation were analysed throughout the rat oestrous cycle. Rats in each phase of the oestrous cycle were assigned to the following experiments: (1) an immunohistochemical study of the number of cells expressing m1AChR or m2AChR in the POA-AHA and (2) analysis of the effects of the unilateral blockade of the m1AChR (pirenzepine, PZP) or m2AChR (methoctramine, MTC) on either side of the POA-AHA on the ovulation rate. The number of m2AChR-immunoreactive cells was significantly higher at 09:00 h on each day of the oestrous cycle in the POA-AHA region, while no changes in the expression profile of m1AChR protein were observed. The ovulation rate in rats treated with PZP on the oestrous day was lower than that in the vehicle group. Animals treated on dioestrous-1 with PZP or MTC had a higher ovulation rate than those in the vehicle group. In contrast, on dioestrous-2, the MTC treatment decreased the ovulation rate. These results suggest that m1AChR or m2AChR in the POA-AHA could participate in the regulation of spontaneous ovulation in rats.