Conspecific Urine Research Articles

Behavioral responses of captive brown bears Ursus arctos to the odor of conspecific urine

The behavior of brown bears Ursus arctos in captivity is often stereotypic. Given that olfactory communication plays a primary role in the life of Ursidae, this study investigated the behavioral responses of brown bears to the odor of conspecific urine and its effectiveness in reducing stereotypies in captivity. The study was conducted in six zoos in Bulgaria, with eight male and eight female brown bears. The urine of an unfamiliar male bear was used as a stimulus. To assess the significance of the stimulus, the duration of a set of behaviors demonstrated by all the animals before and after the odor presentation was compared. All bears showed a keen interest both in the non-odorized boxes and those with the applied odor, demonstrating their relevance both as a novel object and a sensory stimulus. That resulted in an increase in the number of spontaneous behaviors and in the reduction of stereotypic behaviors under the influence of the stimulus during the experiment. Accordingly, the use of conspecific urine odor as an olfactory stimulus can be an important part of enrichment programs for brown bears in captivity and contribute to improving their welfare.

Prioritization of social information by the basolateral amygdala in rats

The amygdala is a collection of nuclei that support adaptive social behavior and are implicated in disorders such as autism. The basolateral complex of the amygdala (BLA), a main subdivision of the amygdala, influences fear responses, motivated behavior, and memory of emotional events via its communication with other amygdalar nuclei and with other brain regions such as the prefrontal cortex, striatum, and hippocampus. The specific role of the BLA in responses to social stimuli is less clear. The present study of female rats investigated the role of the BLA in responding to socially-relevant information by asking how inactivation of the BLA with bilateral infusions of the GABA receptor agonist muscimol would affect spontaneous exploration of wood blocks scented either with conspecific male or female urine or with nonsocial odorants. Conspecific urine samples were used because urine conveys information about sex, health, social status, and reproductive state in rodents. The results revealed that BLA inactivation reduced female rats’ spontaneous preference for social odors over nonsocial odors, specifically for female urine. However, BLA inactivation did not generally impair rats’ ability to distinguish two odors from the same category (e.g., urine odors from two different male rats). The results indicate that the BLA is important for responding to salience of social stimuli but not for discriminating between different individuals, a result that has important implications for amygdalar modulation of downstream attention, motivation, and memory processes for social stimuli.

Experimental Evaluation of Spontaneous Olfactory Discrimination in Two Nocturnal Primates (Microcebus murinus and M. lehilahytsara).

Solitary species often employ chemocommunication to facilitate mate localization. In the solitarily foraging, nocturnal mouse lemurs (Microcebus spp.), females advertise their short period of estrus acoustically and by increased scent marking, whereas males search widely for receptive females. Both sexes can be trained by operant conditioning to discriminate conspecific from heterospecific urine scent. However, it is not known, if males during and outside the reproductive season show different spontaneous interest in conspecific female urine, and if urine from estrous females elicits a higher investigation response than that from diestrous females. We established a spontaneous discrimination paradigm and quantified olfactory investigation responses of 21 captive male mouse lemurs of M. lehilahytsara and M. murinus when presenting 1 conspecific and 1 heterospecific female urine odor sample simultaneously. Overall, M. murinus investigated stimuli significantly longer than M. lehilahytsara. Moreover, males of M. murinus showed significantly longer olfactory investigation at conspecific urine samples during but not outside the reproductive season. This indicates that female urinary cues are spontaneously discriminated by male M. murinus and that this discrimination is more relevant during the reproductive season. However, males of both species did not show different responses toward urine samples from estrous versus diestrous females. Finally, male age did not correlate with the overall duration of olfactory investigation, and investigation levels were similar when testing with fresh or frozen urine samples. In conclusion, this new spontaneous discrimination paradigm provides a useful additional tool to study olfactory communication of nocturnal primates from the receiver's perspective.

Seasonal Changes in the Hormonal Response of Male Eversmann’s Hamsters (Allocricetulus eversmanni, Cricetinae, Rodentia) to Olfactory Signals from Conspecific Females

Reproductive success demands both the male and female reaching a particular physiological status, which is usually stimulated in rodents by certain olfactory signals. The hormonal response of male Eversmann’s hamster (Allocricetulus eversmanni) to the natural excretions (urine, midventral gland secretion (MVGS) of conspecific females was studied during several seasons of the year, with the animals kept in conditions of natural lighting and temperature. In the fall, no reliable changes in the testosterone level in males in response to any signal presented were noted. In the winter and spring, a reliable (P< 0.05) increase in the testosterone level was caused by the female MVGS odor. In the summer, a similar reaction only to conspecific female urine (P< 0.05) was noted. Moreover, in the summer and fall, males showed a reliable decrease in the cortisol level in response to the odor of female urine (P< 0.05). In the winter and spring, a similar result was caused by exposure to both odors. The progesterone level in males reliably (P< 0.05) increased upon exposure to both female urine and MVGS in all seasons of the year, except for the female MVGS in the summer. Therefore, the decreased cortisol level in combination with the simultaneously increased testosterone and progesterone levels allow the males of the species under study to achieve their maximum reproductive success, despite the high degree of their intraspecific aggression.

Evidence of individual odors and individual discrimination in the raccoon,Procyon lotor

Abstract Although raccoons (Procyon lotor) were originally categorized as solitary carnivores, recent evidence shows that some raccoons have overlapping home ranges, travel in groups, and share dens. Moreover, raccoons use communal latrines and scent mark, suggesting that chemical signals may be important for communication. Using a familiarization–discrimination technique we investigated whether raccoons can discriminate individual differences in the odors of conspecific urine or feces. The subjects were wild caught (n = 10 raccoons for urine experiments; n = 8 raccoons for feces experiments) and tested in a large outdoor enclosure. We demonstrated that raccoons can distinguish individual differences in the odor of unfamiliar and unrelated conspecific urine, but not in the odor of feces. Gas chromatography was also done on the urine samples to look for chemical differences. The gas chromatograms showed visible differences and qualitative as well as quantitative differences in chemical composition. This is...

Puumala hantavirus infection alters the odour attractiveness of its reservoir host.

The random-mixing assumptions of many parasite-transmission models are challenged if healthy individuals can alter their behaviour to reduce their risk of infection. Some pathogens reduce the attractiveness of their hosts' excretions, for example, potentially altering contact rates and thus the predicted force of infection for pathogens transmissible by contact with excretions. For bank voles (Myodes glareolus), contact with contaminated urine is an important route of transmission for Puumala hantavirus (PUUV); however, it is not known whether PUUV infection changes the voles' urinary odours or their attractiveness. Here, we use a Y-maze to test whether PUUV infection alters the attractiveness of male bank voles' urine. We presented wild-caught PUUV-free male and female bank voles with PUUV-infected conspecific urine, uninfected urine and a water control, and measured the relative and absolute latency to first visit, number of visits, and total time bank voles spent investigating each treatment over 30 min. PUUV infection significantly altered the bank voles' initial response to conspecific urine, with fewer visits and less time spent close to infected urine relative to uninfected urine, and less total time spent near the infected urine than the uninfected urine or control. These strong preferences weakened over the 30-min trial, however, partly due to a general decline in male activity, and there were no absolute differences between the treatments overall. This suggests that PUUV infection does change the attractiveness of bank vole urine to conspecifics, and we discuss the implications of these results for random-mixing assumptions.

The effect of castrating male dogs on their use of the vomeronasal organ when investigating conspecific urine deposits

The effect of castrating male dogs on their use of the vomeronasal organ when investigating conspecific urine deposits

Effect of conspecific and heterospecific urine odors on the foraging behavior of the golden spiny mouse

The common spiny mouse (Acomys cahirinus) inhibits the foraging activity of the golden spiny mouse (A. russatus). These two sympatric species of spiny mice, which are considered habitat competitors, occur in extreme arid environments. To test this theory of competition, the influence of urinary odors of both conspecific and heterospecific mice on the foraging behavior of A. russatus was studied under controlled laboratory conditions. Twenty adult males, born in captivity and unfamiliar to the odors of the donor mice, were tested in 3 experimental conditions choosing between 2 seed patches that were scented with urine of either heterospecifics (A. cahirinus), conspecifics (A. russatus) or controls (odors of the tested individual). Of the 20 males, 12 were also tested with urine of unfamiliar gerbils, bushy-tailed jird, considered as competitors in the field. Both conspecific and heterospecific urine samples from Acomys significantly reduced foraging behavior of A. russatus when compared to the control odor. The inhibitory effect of the Acomys urine does not result from the novelty of chemical stimuli of the urine because no effect was shown with unfamiliar gerbil urine. The findings are in accordance with the general theory that A. cahirinus dominates the foraging activity of A. russatus. We hypothesize that chemical cues in the urine of Acomys spp. might induce a negative effect on the foraging behavior of A. russatus.

Photoperiod Mediated Changes in Olfactory Bulb Neurogenesis and Olfactory Behavior in Male White-Footed Mice (Peromyscus leucopus)

Brain plasticity, in relation to new adult mammalian neurons generated in the subgranular zone of the hippocampus, has been well described. However, the functional outcome of new adult olfactory neurons born in the subventricular zone of the lateral ventricles is not clearly defined, as manipulating neurogenesis through various methods has given inconsistent and conflicting results in lab mice. Several small rodent species, including Peromyscus leucopus, display seasonal (photoperiodic) brain plasticity in brain volume, hippocampal function, and hippocampus-dependent behaviors; plasticity in the olfactory system of photoperiodic rodents remains largely uninvestigated. We exposed adult male P. leucopus to long day lengths (LD) and short day lengths (SD) for 10 to 15 weeks and then examined olfactory bulb cell proliferation and survival using the thymidine analog BrdU, olfactory bulb granule cell morphology using Golgi-Cox staining, and behavioral investigation of same-sex conspecific urine. SD mice did not differ from LD counterparts in granular cell morphology of the dendrites or in dendritic spine density. Although there were no differences due to photoperiod in habituation to water odor, SD mice rapidly habituated to male urine, whereas LD mice did not. In addition, short day induced changes in olfactory behavior were associated with increased neurogenesis in the caudal plexiform and granule cell layers of the olfactory bulb, an area known to preferentially respond to water-soluble odorants. Taken together, these data demonstrate that photoperiod, without altering olfactory bulb neuronal morphology, alters olfactory bulb neurogenesis and olfactory behavior in Peromyscus leucopus.

Seasonal peculiarities of female hormonal response of females to conspecific chemical signals of the male in two species of the genus Phodopus

Changes in diestrous female blood plasma progesterone, estradiol, and cortisol in response to odors of urine and midventral gland secretion (MVGS) of conspecific males during different seasons have been studied in the desert hamster (Phodopus roborowskii and Djungarian hamster (Phodopus sungorus). In desert hamster females, a statistically significant (p < or = 0.05) increase in the plasma hormonal level was observed: for progesterone in response to conspecific male MGVS in all seasons except winter, and to conspecific male urine in spring and summer; for cortisol in response to male MVGS and urine in all seasons except spring; and for estradiol in response to male MGVS in autumn. Djungarian hamster females demonstrated a statistically significant increase in the plasma progesterone level in response to conspecific male MVGS and urine in winter and summer, and no response to the estradiol and cortisol level for both odors in all seasons.

The effects of sex, gonadectomy and status on investigation patterns of unfamiliar conspecific urine in domestic dogs, Canis familiaris

Little is known about social roles of urine marking and mark investigation in interpack communication in canids beyond mate acquisition, or of the influence of gonadal hormones on interpack urinary communication. We studied the responses of male and female, intact (nonoestrous) and gonadectomized Labrador retrievers to urine from unfamiliar dogs of the same four reproductive categories. We compared two measures of subject social status within subjects' home groups and measured the effect of subject status on urine investigation duration. We also compared the responses of subjects to urine from familiar and unfamiliar dogs. All subjects showed high interest in unfamiliar urine samples, but differed in their preference for particular unfamiliar urine types. Intact males, intact females and spayed females investigated urine from intact males and females equally, whereas neutered males investigated urine from intact males longer than urine from intact females. Urine from intact males and females elicited longer investigation than did urine from gonadectomized sources. Males showed no difference in investigation of familiar and unfamiliar urine, whereas females showed a nonsignificant tendency to investigate urine from unfamiliar dogs longer than urine from groupmates. Low-status subjects investigated urine longer than high-status subjects. Sex, status and familiarity patterns suggest that males and females, both intact and gonadectomized, have strong interest in unfamiliar urine and investigate urine to assess unfamiliar conspecifics in multiple social contexts, including mate and threat assessment. These results also suggest that gonadal hormones may affect urine investigation patterns both by increasing sexually motivated urine investigation in males and by creating signals in urine that allow assessment of potentially risky conspecifics.

The olfactory pathway mediates sheltering behavior of Caribbean spiny lobsters, Panulirus argus, to conspecific urine signals

The "noses" of diverse taxa are organized into different subsystems whose functions are often not well understood. The "nose" of decapod crustaceans is organized into two parallel pathways that originate in different populations of antennular sensilla and project to specific neuropils in the brain-the aesthetasc/olfactory lobe pathway and the non-aesthetasc/lateral antennular neuropil pathway. In this study, we investigated the role of these pathways in mediating shelter selection of Caribbean spiny lobsters, Panulirus argus, in response to conspecific urine signals. We compared the behavior of ablated animals and intact controls. Our results show that control and non-aesthetasc ablated lobsters have a significant overall preference for shelters emanating urine over control shelters. Thus the non-aesthetasc pathway does not play a critical role in shelter selection. In contrast, spiny lobsters with aesthetascs ablated did not show a preference for either shelter, suggesting that the aesthetasc/olfactory pathway is important for processing social odors. Our results show a difference in the function of these dual chemosensory pathways in responding to social cues, with the aesthetasc/olfactory lobe pathway playing a major role. We discuss our results in the context of why the noses of many animals contain multiple parallel chemosensory systems.

The impact of a brominated flame retardant on smoltification and olfactory function in Atlantic salmon (Salmo salar L.) smolts

Despite a reduction in exploitation of salmon stocks throughout the NE Atlantic, there continues to be a decline in many populations. The factors regulating these populations remain poorly understood, although there is evidence that environmental conditions experienced in freshwater can effect survival in the marine environment. The aim of this study was to investigate the impact of a brominated flame retardant (hexabromocyclododecane, HBCD) on the parr-smolt transformation in juvenile salmon. It is during this pre-adaptive period to marine life that olfactory imprinting to the natal river is considered to occur. Fish were exposed to low levels of HBCD for 30 days over the peak smoltification period in freshwater, and then transferred to clean seawater for 20 days. Fish were sampled weekly to assess changes in some of the physiological parameters associated with smoltification, and olfactory response to conspecific smolt urine was measured using an electro-olfactogram (EOG). Exposure to HBCD did not affect seawater adaptability, although there was some disruption of plasma thyroid hormone levels, as well as a reduction in olfactory function to conspecific smolt urine. The results are discussed in relation to the marine survival and successful homing of adult salmon.

Source and Specificity of Chemical Cues Mediating Shelter Preference of Caribbean Spiny Lobsters (Panulirus argus)

Caribbean spiny lobsters display a diversity of social behaviors, one of the most prevalent of which is gregarious diurnal sheltering. Previous research has demonstrated that shelter selection is chemically mediated, but the source of release and the identity of the aggregation signal are unknown. In this study, we investigated the source and specificity of the aggregation signal in Caribbean spiny lobsters, Panulirus argus. We developed a relatively rapid test of shelter choice in a 5000-l laboratory flume that simulated flow conditions in the spiny lobster's natural environment, and used it to examine the shelter preference of the animals in response to a variety of odorants. We found that both males and females associated preferentially with shelters emanating conspecific urine of either sex, but not with shelters emanating seawater, food odors, or the scent of a predatory octopus. These results demonstrate specificity in the cues mediating sheltering behavior and show that urine is at least one source of the aggregation signal.

Skin and gland but not urine odours elicit conspicuous investigation by female grey short-tailed opossums, Monodelphis domestica

Chemical communication plays a major role in mammalian behaviour. One mammal with well-developed chemical senses is the grey short-tailed opossum, a small, South American marsupial that has become common in laboratory research. Male and female opossums scent-mark with different body parts, but apparently not with urine, and females enter oestrus following their exposure to male odours. To elucidate the effects of body odours on the behaviour of female opossums, we investigated their ability to discriminate between conspecific odours originating from different body parts. We simultaneously presented female opossums with two cotton balls smeared either with skin and glandular secretions or urine of conspecifics, or with distilled water or blank controls, and we analysed the time females spent investigating each stimulus. Odours of the male suprasternal gland elicited intensive investigation by the test females. Male flank and submandible odours, and female submandible odours, were also attractive to the females. Investigation of male and female urine was comparable to investigation of water and blank controls. We suggest that in this species, which inhabits semiarid areas, urine marking is avoided to reduce dehydration, and consequently urine has lost its biological significance as a chemosignal. On the other hand, glandular and skin secretions, which are more stable than aqueous deposits in dry conditions, allow the opossums to communicate with each other effectively and also to retain body fluids.

Chemobehavioral changes induced by short-term exposures to prochloraz, nicosulfuron, and carbofuran in goldfish.

The behavioral effects of short periods (2, 4, 6, 8 h) of static exposure to prochloraz (imidazole fungicide) and nicosulfuron (sulfonylurea herbicide) were recorded in goldfish (Carassius auratus). Observations were also made in an olfactometer to assess the effects of 8-h exposures to these two pesticides and to carbofuran (carbamate insecticide) on the behavioral responses to the flow of a solution of four L-amino acids (glycine, alanine, valine, taurine), mixed in the same relative proportions as in the urine of conspecifics. Each pesticide was tested at three sublethal concentrations (25, 50, 100 microg/L), and the behaviors recorded were related to swimming pattern, social interactions, and comfort movements. Static exposures to prochloraz affected horizontal displacements, burst swimming, grouping, and buccal movements. Static exposures to nicosulfuron affected burst swimming and grouping. In pesticide-unexposed fish (control), the flow of the amino acid solution induced attraction, decreased sheltering, and increased horizontal displacements, burst swimming, buccal movements, and antagonistic interactions. Compared to the controls, some of the behavioral responses to the solution of amino acids were significantly different after 8 h of subacute exposure to prochloraz and carbofuran. Both pesticides decreased attraction and increased sheltering. In addition, carbofuran decreased buccal movements and antagonistic interactions. Contrastingly, exposure to nicosulfuron showed no significant effect. This study further confirms the great vulnerability of fish behavior and chemocommunication processes to exposure to waterborne pesticides.

Photoperiodic and temporal influences on chemosensory induction of brain fos expression in female prairie voles.

Prairie voles (Microtus ochrogaster) typically stop breeding during winter. Male prairie voles respond to winter day lengths with gonadal regression, whereas female voles are relatively unresponsive to photoperiod. Unlike commonly studied laboratory rodents, female prairie voles do not exhibit spontaneous oestrous cycles. Instead, females are induced into oestrus by chemosensory cues from conspecific male urine. The present study investigated the interaction among day length, chemosensory cues and the initial brain responses during oestrus induction in female voles. A single drop of male conspecific urine, saline or skimmed milk was applied to the nares of female prairie voles housed for 9 weeks in either long (LD 16 : 8 h) or short (LD 8 : 16 h) days. Animals were killed 0.5, 1, 2 or 24 h after chemosensory treatment and their brains were processed for Fos immunocytochemistry. Body mass and ovarian fat pad mass were higher, but uterine and ovarian mass were lower, in short-day compared to long-day females. Regardless of photoperiod, Fos- immunoreactivity increased in the granule layer of the accessory olfactory bulb (AOB), the supraoptic nucleus and bed nucleus of the stria terminalis (BNST) (anterior medial) in females treated with male urine compared to the two control groups. Fos staining intensified in the AOB, medial and posterocortical medial amygdala and BNST (posterior ventral), 1 h and 2 h after urine treatment. In the medial preoptic area, anterior and lateral hypothalamus, and ventromedial nucleus of the hypothalamus, Fos-immunoreactivity was elevated in females 2 h after receiving urine. Overall, long-day females displayed higher Fos expression in response to urine than females maintained in short days. These results identify a putative neural circuitry of oestrus induction in this species, and provide an approximate time line of activation in the brain circuit responsible for oestrus induction in prairie voles.

Young female pigs can discriminate individual differences in odours from conspecific urine

The ability to discriminate odour cues from different conspecifics has been demonstrated in a variety of small mammalian species. We used a habituation–dishabituation procedure to investigate whether 10-week-old female pigs,Sus scrofa , are able to discriminate between urinary odours from similar-aged conspecifics that were unfamiliar (not encountered for at least 7 weeks). We also examined whether environmental factors can affect the ease with which urine from different individuals is discriminated. Subjects receiving urine samples from the same unfamiliar individual in two successive 2-min exposures separated by a 15-min interval showed habituation in their investigation response to the urine in the second exposure. This habituation was maintained in a third 2-min exposure, 15min later, if the urine sample was again from the same individual. However, if the urine sample was from a different unfamiliar individual, there was a dishabituation of the investigation response. This was taken to indicate an ability to discriminate the two samples. These data indicate that young pigs could use urinary cues to discriminate other individuals. Effective individual discrimination should facilitate the formation and maintenance of stable social groupings but could be disrupted if, for example, animals from the same group share common odour cues that mask individually distinctive scents. However, urine samples from individuals living in the same group appeared to be no more difficult to discriminate than those from individuals living in different groups. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.

Olfactory memory in rats, cholinergic agents and benzodiazepine receptor ligands

Drugs and their effects on olfactory learning processes in rats were tested using a modified version of the runway apparatus developed by Ades. Rats were first exposed to a conspecific urine sample and 24 h later were exposed to the same stimulus in the runway. Observations recorded the time spent investigating the urine and the number of sniffs at the site, these being considered to be indices of memory. Diazepam-treated rats (4 or 6 mg/kg) and scopolamine-treated rats (0.5 or 1 mg/kg) showed increases for both parameters. When both drugs were administered simultaneously, the impairing effect was potentiated. However, no changes in learning responses were observed in rats treated with physostigmine (0.125, 0.25, 0.5 mg/kg) or methyl β-carboline-3-carboxylate (0.3, 0.5, 1 mg/kg), although the administration of physostigmine or methyl β-carboline-3-carboxylate was shown to antagonize the impairing effect of diazepam or scopolamine respectively. These observations support the hypothesis of interactions existing between cholinergic agents and benzodiazepine receptor ligands and of such interactions affecting olfactory acquisition processes. The runway apparatus appears to be a valid candidate model to be used for the assessment of pharmacological influences on olfactory learning inrats.

Amygdala but not hippocampal lesions impair olfactory memory for mate in prairie voles (Microtus ochrogaster).

Exposure to an unfamiliar male conspecific results in pregnancy interruption (i.e., the Bruce effect) in rodents. Unlike most laboratory rodents, female prairie voles (Microtus ochrogaster) are induced into estrus by chemosensory stimuli contained in the urine of male conspecifics while grooming the anogenital (A-G) region of unfamiliar males. Female prairie voles maintain a brief "memory" for the stud male for 8-10 days after mating. Subsequent exposure to the same mate within this 8- to 10-day window does not elicit A-G investigation by the female and pregnancy block does not result. However, exposure to the original male after 10 days evokes A-G investigation and pregnancy block. To determine the neuroanatomic area(s) involved in olfactory memory for mate, female voles received bilateral electrolytic lesions of either the amygdala or hippocampus. Females were subsequently exposed to males for 48 h, separated for 3 days, then reintroduced to their original mate for 24 h. Although pregnancy rate did not differ among the experimental groups, a greater proportion of amygdala-lesioned females displayed pregnancy block when reexposed to their previous mates compared with hippocampal- or sham-lesioned voles. Amygdala-lesioned voles also displayed a greater number of A-G investigations compared with the other groups. Performance on olfactory tests was not impaired. Taken together, these results suggest that the amygdala plays an important role in olfactory memory for mate in prairie voles.