Fight or flight? Sexual cycle determines the behaviour of female guinea pigs

Also in female guinea pigs, Cavia porcellus, hormone levels fluctuate with fertility. These variations, caused by the rhythm of oestrus and anoestrus, may influence the social behaviour of the rodents given that guinea pigs naturally maintain a hierarchy in which dominant animals take advantage.

A research team from the University of Veterinary Medicine, Vienna, and the University of Vienna analysed social behaviours and hormone levels to find out how female guinea pigs are affected by the oestrus cycle during the encounter with a female conspecific. The results clearly indicate that females tend to flee from one another during their fertile periods, but outside these periods they risked the confrontation.

Hormonal rollercoaster determines behaviour

So far, there has been hardly any research on the influence of the “hormonal rollercoaster” on the social behaviour of female guinea pigs. “These rodents live in social hierarchies, similar to many other mammals. Such hierarchies are established through confrontations between conspecifics. Animals with a good intuition of when to compete or withdraw are more successful and better integrated,” explained Lisa-Maria Glenk from the Unit of Comparative Medicine of the Messerli Research Institute.

Stress hormones play a key role in this process because they mobilise energy for flight or fight in the body. “To gain a better understanding of how sexual and stress hormones modulate behaviour, we confronted guinea pigs with an unknown female conspecific in an experimental arena,” said the lead author. Together with her colleagues from the Department of Behavioural Biology of the University of Vienna, Glenk observed the female guinea pigs at two different times of the cycle: oestrus, i.e. the phase in which the animals are able to reproduce, which starts with the temporary partial rupture of the vaginal closure membrane, and anoestrus during which the membrane remains closed until the next fertile period.

From the behavioural observations and laboratory results, the researchers concluded that aggressive behaviour occurred independently of the sexual cycle. When they were in heat, however, the animals fled from their competitors significantly more often. Peaceful “sitting together” was only observed during anoestrus. Furthermore, blood concentrations of the hormone cortisol before the experiment were lower in unreceptive animals, but significantly rose during the confrontation. There was only a marginal increase in the release of testosterone in both cycle phases. The results show a considerable influence of sexual cycle phase on stress hormones as well as social and flight behaviour. “It is particularly interesting that physical contact increased during anoestrus under the strong increase of cortisol. This behavioural strategy could serve as a stress buffer for the animals,” said Glenk.

Service:
The article “Fight or flight? Effects of vaginal oestrus on cortisol, testosterone, and behaviour in guinea pig female-female interaction.” by Lisa M. Glenk, Ivo H. Machatschke and Bernard Wallner. was published in Behavioural Processes.
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About the University of Veterinary Medicine, Vienna
The University of Veterinary Medicine, Vienna in Austria is one of the leading academic and research institutions in the field of Veterinary Sciences in Europe. About 1,300 employees and 2,300 students work on the campus in the north of Vienna which also houses five university clinics and various research sites. Outside of Vienna the university operates Teaching and Research Farms. The Vetmeduni Vienna plays in the global top league: in 2018, it occupies the excellent place 6 in the world-wide Shanghai University veterinary in the subject „Veterinary Science“.

Scientific Contact:
Lisa Maria Glenk
Messerli Research Institute
University of Veterinary Medicine Vienna (Vetmeduni Vienna)

Released by:
Georg Mair
Science Communication / Corporate Communications
University of Veterinary Medicine Vienna (Vetmeduni Vienna)
T +43 1 25077-1165

About Messerli Research Institute
The Messerli Research Institute was founded in 2010 with support from the Messerli Foundation (Sörenberg, Switzerland) under the management of the University of Veterinary Medicine, Vienna in cooperation with the Medical University of Vienna and the University of Vienna. The research is devoted to the interaction between humans and animals, as well as its theoretical principles in animal cognition and behavior, comparative medicine and ethics. Its work is characterized by its broad interdisciplinary approach (biology, human medicine, veterinary medicine, philosophy, psychology, law) and strong international focus.

contact for scientific information:
Lisa Maria Glenk
Messerli Research Institute
University of Veterinary Medicine Vienna (Vetmeduni Vienna)

original publication:
https://doi.org/10.1016/j.beproc.2018.04.008

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