This regulation was not observed in pseudopregnancy.
Micaela S Sordelli, Jimena S Beltrame, Juliana Burdet, Elsa Zotta, Romina Pardo, MaximilianoCella, Ana M Franchi, Maria Laura Ribeiro 2011, 'The effect of anandamide on uterine nitric oxide synthase activity depends on thepresence of the blastocyst.', PLoS ONEhttp://europepmc.org/articles/PMC3084697?pdf=render. Retrieved from PLOS CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
During pseudopregnancy, non-pregnant females exhibit physiological and behavioral changes similar to pregnancy.
Erin L. Willis, David C. Kersey, Barbara S. Durrant, Andrew J. Kouba 2011, 'The Acute Phase Protein Ceruloplasmin as a Non-Invasive Marker of Pseudopregnancy,Pregnancy, and Pregnancy Loss in the Giant Panda', PLoS ONE10.1371/journal.pone.0021159. Retrieved from PLOS CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Medroxyprogesterone increased uterine weight, caused a swelling of the endometrium and a pseudopregnancy estrus.
Andrea Actis, Maximo Croci, Emanuel Levin, Rosa Bergoc 2002, '8-Chloro-cAMP-Related Changes on Mice Uteri', The Scientific World Journalhttp://dx.doi.org/10.1100/tsw.2002.282. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Then, pseudopregnancy was induced and ovarian tissue samples were removed for histological and molecular assessment.
Nasim Beigi Boroujeni, Mohammad Reza Gholami 2017, 'Effect of the Ethanolic Extract of Salvia officinalis on Ovarian Angiogenesis in Miceat Preimplantation: A Morphological and Molecular Analysis', Jentashapir Journal of Health Researchhttp://dx.doi.org/10.5812/jjhr.44386. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
The concentration of both these metabolites changed during pseudopregnancy and maximum levels were observed at day 7.
St-Louis Isabelle, Singh Mohan, Brasseur Kevin, Leblanc Valérie, Parent Sophie, AsselinEric 2010, 'Expression of COX-1 and COX-2 in the endometrium of cyclic, pregnant and in a modelof pseudopregnant rats and their regulation by sex steroids', Reproductive Biology and Endocrinologyhttp://www.rbej.com/content/8/1/103. Retrieved from DOAJ CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)
Therefore, a physiological test to distinguish between pregnancy and pseudopregnancy in pandas has eluded scientists for decades.
Erin L Willis, David C Kersey, Barbara S Durrant, Andrew J Kouba 2011, 'The acute phase protein ceruloplasmin as a non-invasive marker of pseudopregnancy,pregnancy, and pregnancy loss in the giant panda.', PLoS ONEhttp://europepmc.org/articles/PMC3135589?pdf=render. Retrieved from PLOS CC BY 4.0 (https://creativecommons.org/licenses/by-sa/4.0/legalcode)