The physiological reaction of Siberian hamsters (Phodopus sungorus, Cricetidae) to chemical signals of perspective mating partners before and during courtship.

E Yu Kondratyuk,P A Zadubrovskiy,A V Sakharov,I V Zadubrovskaya

doi:10.1242/bio.057570

Abstract

ABSTRACTIn this investigation we assessed the physiological reaction of hamsters in response to chemical signals from potential sexual partners, and also after a private meeting with them, which allowed us to ascertain the type of mating system for this species. The reception of olfactory signals led to an increase in peroxidase activity in the blood for both sexes, indicative of activity of a non-specific line of immune defense in recipients. The increase in blood cortisol level in response to the chemical signals of a partner was only observed in females. Males spent more time near samples of estrous females, with elevated levels of cortisol in the urine. In olfactory tests, an hour after grouping all the individuals in pairs there was a significant increase in blood peroxidase activity, which indicates the reaction of a non-specific link in the immune system of partners. This increase was greater in the pairs with a mutual preference. Females from these pairs demonstrated a substantial decrease in stress hormone levels in the plasma after an hour of mating in comparison to females prior to mating, and in non-preferred coupling.

Highlights

As is well known, social odors play a substantial and often essential role in mammalian reproduction
The choice of a potential mate in mammals is based on the direct perception of chemical signals containing information that is specific to the species, sex, social and physiology status
It has been shown previously that fecal samples are an additional source of chemosignals for Siberian hamsters in the summer (Novikov, 1988)

Summary

Introduction

Social odors play a substantial and often essential role in mammalian reproduction. Chemosensory signals can accelerate or decelerate maturation and function in adults of the hypothalamic-pituitary-gonadal (HPG) axis of recipients, such that an increase in HPG function occurs in response to the appearance of mating partners (Boehm et al, 2005) and there is a decrease in HPG function in reproductively sub-optimal conditions (stress effects) (Toufexis et al, 2014). Perception of scents from opposite-sex conspecifics initiates behaviors that increase the likelihood of contacting mates: olfactory investigation, scent marking and vocalizations. Even after contact occurs, the initiation of copulatory behavior in both sexes may still depend on chemosensory cues, perhaps because these cues allow a more detailed evaluation of the mating partner (Petrulis, 2013).

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