Exposures to L‐felinine Suppressed Plasma Testosterone in Laboratory Rats

Felinine is a unique sulfur‐containing amino acid found in the urine of domestic cats and select members of the Felidae family (Rutherfurd et al. 2002). L‐felinine and its sulfur‐containing volatile derivatives excreted with urine in sex‐ and age‐dependent manner (Miyazaki et al. 2006). These cat‐specific volatile compounds may represent pheromones used as territorial markers for conspecific recognition or reproductive purposes by mature cats (Miyazaki et al. 2008). Species‐specific compounds may be used also by other species to recognize potential predators and their physiological status. In our previous studies we showed that exposures of rats from laboratory heterogenous population during gestation to the cat urine or L‐felinine significantly affected reproductive output. We observed significantly lower weight of newborn pups and skewed sex ratio in favour in males. At the behavioral level, exposed to cat urine/L‐felinine male rats showed fewer mountings and mountings with intromissions in presence of receptive females. In the current study we examined the influence of domestic cat‐specific compound L‐felinine on testosterone secretion in male rats. Intact cat urine was used as positive control; tap water was used as negative control. Test subjects were 3–4 month old Norway rats Rattus norvegicus from laboratory population. Males were placed singly two weeks prior to experiment. We used concentration of L‐felinine comparable to naturally occurring in the adult cat urine (Rutherfurd et al. 2002). Cotton balls soaked with L‐Felinine (0.05% w/v, 0.2 ml, US Biologicals), cat urine (0.2 ml) or tap water (0.2 ml) in plastic perforated containers were placed directly into home cages of rats. We renewed test solutions twice a week. Experimental animals were randomly assigned to one of treatment groups. Blood samples (50 μl) were obtained from rear foot pad (Miller et al. 1997). Plasma testosterone was assayed (in duplicate) by enzyme immunoassay method (EIA‐1559, DRG). Exposure of male rats to cat urine (0.2 ml) during two weeks significantly suppressed plasma testosterone (p=0. 0020, n=10, t‐test). Analogous exposures to L‐felinine (0.05 %, 0.2ml) produced quite similar effect (p =0.049, n=10, t‐test) in male rats. The effect was dose dependent: we did not observe suppression of plasma testosterone when lower amount of L‐felinine solution (0.05 %, 0.1ml.) was applied to home cage of male rats. It appears to be that altered sexual behavior of male rats exposed to L‐felinine/cat urine could be explained by significantly lowered testosterone secretion. The expression of the secondary defense reactions by laboratory naive rats and the failure tohabituate at the hormonal level may indicate an innate nature of the response. Support or Funding Information Supported by Russian Foundation for Basic Research grant 19‐34‐70024 mol_a_mos This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .