Washing, drying, and anointing in adult humans (Homo sapiens): commonalities with grooming sequences in rodents.

Very few behavioral patterns generalize across human and nonhuman species. We describe washing, drying, and anointing sequences in humans (Homo sapiens) that may have analogies with other species. The rank ordering of washing, drying, and anointing body parts was obtained over 3 successive days for 37 men and 60 women. Variation in rank ordering of body parts was nonrandom, and a cephalocaudal progression was evident for each behavior. Reliability of the behaviors as well as the correlations across rankings were highly significant, which indicates a generalized cephalocaudal progression for all 3 behaviors. Women's anointing was most variable, which suggests a more specific function. The cephalocaudal action pattern described for humans is similar to that for Mongolian gerbils and laboratory rats. Cross-species functions, such as these, may add to our understanding of common developmental and learning processes.

Lipopolysaccharide decreases ambient temperature preference in Mongolian gerbils, Meriones unguiculatus.

Animals infected with a pathogen often increase their body temperature, a reaction which can limit the reproduction of the pathogen and stimulate the immune system. Excessive body temperature increases, however, can decrease survival. The Mongolian gerbil responds to the endotoxin, lipopolysaccharide LPS, with increased body temperature. Relative to saline-injected animals, gerbils made hyperthermic with LPS choose an environmental temperature 6.7 degrees C lower. Apparently the gerbil is attempting to limit its body temperature increases by selecting a lower ambient temperature.

Body temperature and grooming in the Mongolian gerbil.

The Mongolian gerbil, Meriones unguiculatus, like many other rodents, releases a complex mixture of pigments and lipids from the Harderian gland during a self-groom. The material exits from the external nares of the nose, is mixed with saliva, and spread widely over the pelage. Cold temperatures, especially, are effective in initiating grooming. A self-groom is associated with an increase in body temperature (compensatory thermogenesis in the cold). In addition to acting as a chemosignal, the Harderian material serves two major homeostatic functions: (1) the lipids on the pelage act to insulate the animal against cold and wetness, and (2) the lipids and pigments darken the pelage and increase radiant absorption. Body temperature is thus maintained at a higher level than would otherwise be the case. The amount of Harderian material found on the pelage varies with Harderianectomy, sandbathing, and ambient temperatures. Animals prevented from sandbathing accumulate excess lipids on the pelage, and cold temperatures facilitate the acquisition of lipids on the pelage. Under hot temperatures the grooming of Harderian substances is repressed and the frequency of sandbathing is increased. Thus pelage lipids are reduced in two ways. The amount of Harderian material released during an autogroom is inversely related to the ambient temperature, whereas the amount of saliva used for evaporative cooling is positively related to ambient temperature. The net effect is that pelage lipids are increased and maintained during cold conditions, and are reduced during hot conditions. In hot environments the gerbil switches from the spread of Harderian material for insulation to the spread of saliva for evaporative cooling. The gerbil optimizes its body temperature by varying the frequency of grooming and sandbathing, and by altering the amount of Harderian material and saliva released. Other species living in arid environments may use similar mechanisms to stabilize body temperature. Self-grooming is a critical behavior for meeting thermal needs, and is complexly integrated with related processes.

Harderian gland exudates in the male Meriones unguiculatus regulate female proceptive behavior, aggression, and investigation.

Harderian gland secretions exit from the nose of Meriones unguiculatus during an autogroom (Thiessen, 1977). The exudates act as an attractant pheromone and as a thermoregulatory barrier when spread throughout the pelage. A recent study demonstrated that Harderian exudates in the male guide proceptive behavior in the female (Harriman & Thiessen, 1985). The present study replicated this finding by showing that estrous females direct fewer proceptive acts toward males lacking Harderian glands. In addition, it was found that females are more defensively aggressive toward Harderianectomized males and prefer to spend more time in the vicinity of intact males. It is speculated that Harderian spread allows the female to assess the reproductive competence of the male.

Ventral scent marking in Meriones unguiculatus may contribute to thermoregulation.

Three experiments were conducted with adult male Meriones unguiculatus in an attempt to demonstrate that ventral scent marking can act to transfer body heat to the object marked. Experiment 1 showed that surgical removal of the ventral gland pad reduced the amount of heat transferred by 50%, even though intact and glandless animals did not differ in the average frequency of scent marking. Experiment 2 demonstrated that the difference in heat transfer due to the presence or absence of the scent pad was not due to differential pressure applied to the substrate during marking. Experiment 3 showed that the pattern of ventral hair spread that occurs as an animal moves over an object is different between intact and glandless animals but that this difference does not account for the difference in heat transfer. It is suggested that heat transfer to the environment with ventral scent marking may increase thermoregulatory competence and also may function to volatilize sebum used in chemocommunication.

Harderian letdown in male mongolian gerbils (Meriones unguiculatus) contributes to proceptive behavior.

Adult female gerbils in estrus, like other female rodents, tend to engage in proceptive displays toward conspecific males. The displays, which may be interspersed with the more usual female agonistic activity, if the males are strangers, are preceded by female olfactory investigation of those head areas in the male gerbil where Harderian letdown accumulates most densely. This study explored the possibility that the male Harderian glands are a source of olfactory signals which promote proceptive behavior but suppress female agonistic behavior. Female gerbils in estrus were found to display significantly less than normal rates of proceptive behavior toward Harderianectomized males. The proceptive activity which was observed appeared to be slowed, but the typical pattern was retained. Female aggression, however, was not affected by their estrous condition or by the Harderian state of the males. Possibly Harderian letdown in male gerbils may inform females as to the reproductive competence of the males.

Harderian gland involvement in facial lesions in the Mongolian gerbil.

Fourteen Mongolian gerbils with naturally occurring facial lesions were assigned randomly to 1 of 3 groups. The Harderian gland was removed surgically from the animals in group 1; a sham operation left the Harderian gland intact in animals in group 2; and animals in group 3 were housed on a sand substrate rather than the usual pine shavings. The progress of this disease state was monitored over a 2-month period. Animals in groups 1 and 3 recovered or improved, whereas the condition of the control animals worsened. It was concluded that the facial lesions are associated with an accumulation of the Harderian gland secretions around the external nares and that laboratory ambient temperatures and cage bedding may modify the development of the condition.

Brood patch function for the ventral scent gland of the female Mongolian gerbil, Meriones unguiculatus.

Infants of gerbil mothers whose ventral scent gland has been excised were compared on a number of developmental indices with pups of mothers who had had an equivalent section of lateral skin removed. The removal of the mother's ventral scent gland retarded the offsprings' pattern of ultrasounding during the 1st 21 days of development. In addition, infants from such mothers showed a retarded righting reflex. Inhibitions in the developmental behavior of gerbil pups might have resulted from less effective heat transfer during mother-pup contact. Indeed, excision of the gland resulted in lower ventral temperatures. The duality of function of the gland as an odor source for communication and as a heat source for offspring development suggests integrated communicative and thermoregulatory processes.

Haloperidol and clonidine increase, and apomorphine decreases ultrasonic vocalizations by gerbils.

Ten psychotropic drugs that have putative effects on central brain neurotransmitters were assessed for influences on ultrasonic signaling relative to general activity in male Mongolian gerbils. Haloperidol (1 mg/kg IP), a dopamine antagonist, and clonidine (0.1 mg/kg IP), a norepinephrine agonist, increased ultrasonic signaling, and apomorphine (5 mg/kg IP), a dopamine agonist, decreased ultrasonic signaling. Catecholamines may modulate ultrasonic signaling in the gerbil. Body temperature changes were positively with ultrasonic emission in tests after saline, haloperidol, apomorphine, and 5-hydroxytryptophan (30 mg/kg IP).

Scent of gerbil cuisine.

Preweanling and postweaning offspring of gerbil parents fed Purina Laboratory Chow or Pooch dog food show selective preference for odors coming from other animals of these same diets. Odors with differential quality include whole animal, cage material and ventral scent gland sebum. Apparently diet alters chemosignals, even those from a specialized scent gland. Species-specific pheromones may be dependent on ingested foodstuffs or other ecological chemicals.

Vitamin E and sex behavior in mice.

C57BL/6J male mice responded to dietary deficiency of vitamin E with reduction in spermatogenesis. Sex behavior and seminal vesicle weight were unaffected. Supplements of alphabeta-tocopherol (vitamin E) at 0.33 or 72 IU per day maintained spermatogenesis but did not affect seminal vesicles or sex behavior.

Identification of a ventral scent marking pheromone in the male Mongolian gerbil (Meriones unguiculatus).

Sebum from the ventral scent marking gland of the male Mongolian gerbil was fractionated and tested for its ability to elicit behavioral response in a conditioning task and in a stimulus preference situation. The active fraction was identified as phenylacetic acid; both it and a synthetic sample elicited the same behavioral response. Phenylacetic acid appears to be a major pheromone of the male Mongolian gerbil.