D.D. Thiessen

The control and function of maternal scent marking in the Mongolian gerbil

Abstract Both scent marking frequency and nest building activity increase during pregnancy and early lactation, and then gradually fall off to prepregnancy levels by the end of lactation. Females ovariectomized two days after parturition fail to show the normal increase in marking in early lactation. In addition, ovariectomy of nonpregnant females causes a significant decline in marking frequency, thus implicating ovarian secretions in the control of female scent marking. The presence of the mothers sebum on a strange pup enhances the pups probability of being retrieved to the nest, suggesting that scent marking aids the mother in identifying her pups. The role of the hormones of pregnancy in regulating many aspects of maternal behavior is emphasized.

Central control of territorial marking in the mongolian gerbil

Abstract Mongolian gerbils ( Meriones unguiculatus ) mark objects in their environment with a ventral sebaceous scent gland. The response is androgen-dependent. This report gives evidence that small doses of testosterone, either injected into the lateral ventricles or implanted with cannulae in the hypothalamus, can evoke the behavior. Control implants into the hypothalamus or testosterone implants into other brain areas are ineffective. Actinomycin D, when combined with testosterone in the ventricles, blocks the induction of marking.

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.

Temperature regulation and social grooming in the Mongolian gerbil (Meriones unguiculatus).

It has previously been shown that temperature regulation in rodents depends on the integrity of the salivary glands. More recently it was found that every groom in the Mongolian gerbil is accompanied by a release and spread of Harderian material from the nares of the nose. The exocrine substance acts as an attractant or attention pheromone. It also stimulates self-grooming in conspecifics. Here, we show that each groom regulates body temperature, whether stimulated by social interaction or by an ambient heat source. Momentary depression of locomotion may contribute significantly to this effect. Moreover, gerbils with free access to areas on a horizontal thermal gradient choose to groom at 28°C regardless of social status. However, when dominant and subordinate males compete on the gradient, dominant animals control the area around 28°C and depress grooming frequency in subordinates. The data suggest that thermoregulatory grooming, ambient temperature preference, social behavior, and Harderian signaling are intimately related. “Displacement grooming” as defined by ethologists may result because of these interactions.

Estrogen control of scent marking in female mongolian gerbils (Meriones unguiculatus)

Ovarian hormones control a species-specific scent marking behavior displayed by female Mongolian gerbils. The present studies examined steroid induction of scent marking in female gerbils that regularly displayed the response prior to treatment and in females that rarely or never scent marked. In females that regularly scent marked preoperatively, marking behavior and scent gland size decreased after ovariectomy and were reinstated by estrogen given alone or with progesterone. Steroid injections did not stimulate scent marking in ovariectomized females that scent marked very seldom preoperatively, although the hormones promoted gland growth. In contrast to other studies, estrogen and estrogen plus progesterone proved equally effective in all cases.

Regulation of scent marking in the female Mongolian gerbil Meriones unguiculatus

Abstract The role of estrogens and progesterones in the control of scent marking in the female Mongolian gerbil ( Meriones unguiculatus ) has remained unclear. Two experiments were conducted which attempted to assess the ovarian contribution to the regulation of this behavioral pattern. In Experiment 1, ten groups of ovariectomized females were treated with one or a combination of steroid hormones which had been selected on the basis of being known secretory products of the ovaries of other rodent species. Only testosterone propionate or a combination of testosterone propionate and estrogen were effective in stimulating marking. Both androgens and estrogens supported gland growth whereas only estrogens supported uterus growth. In a second experiment, androstenedione, a primary precursor to testosterone and estrogen, was administered to intact and ovariectomized females for a period of four weeks. Each female received a weekly marking test following treatment. Intact females responded with a rapid and significant increase in marking frequency whereas ovariectomized and intact control females continued to mark at control levels. It was concluded that the conversion of androstenedione or related hormones into behaviorally active compounds during period of high marking (e.g., as during late gestation and lactation and lactation) is at least one means by which marking is regulated in the female gerbil.

Estrogen and progesterone interaction in the regulation of scent marking in the female Mongolian gerbil (Meriones unguiculatus)

Abstract Ovariectomized female gerbils were treated with either 0, 20, 40, 80 or 160 μg estradiol benzoate (EB) followed in 36 hr by either 0, 250, 500 or 1000 μg progesterone. The animals were tested for ventral scent marking nine hr after progesterone treatment. Treatment with 20, 40 or 80 μg EB resulted in a significant increase in marking in the ovariectomized female for each dose of progesterone used. One hundred and sixty μg EB was not effective while 80 μg was the most effective dose at each dose of progesterone. There were no differences among the 80 μg EB groups in mean marking frequency as long as progesterone was present. Neither estrogen alone nor progesterone alone was effective in stimulating a significant level of marking. An additional sample of ovariectomized females were maintained for four weeks on either 2.5, 5, 10, 20 or 40 μg EB and tested for marking each week 45 hr after EB administration. On the fifth week 250 μg progesterone was given each week 36 hr following EB with behavioral testing nine hr later. Such a regime was followed for four weeks. Marking remained at zero levels on weeks one through four. EB + progesterone on weeks five through eight, however, resulted in a significant increase in marking in animals receiving 10 μg EB (mean = 9.0 ± 3.5), 20 μg EB (mean = 6.6 ± 2.5) and 40 μg EB (mean = 9.2 ± 4.2). It was concluded that both estrogen and progesterone were essential for the support of marking in this sample of low-marking females and that since there were no reliable differences between groups receiving different doses of progesterone, estrogen was the primary stimulus controlling marking behavior, with progesterone perhaps playing a modifying role.

Comparative studies of glandular scent marking in Meriones tristrami an Israeli gerbil

Abstract Meriones tristrami a gerbil species from Israel, scent marks low-lying objects in its environment with a ventral sebaceous scent gland. Castration of males was followed by atrophy of the scent gland, and a decrease in marking frequency. Methyltestosterone (5 mg/day), administered in the diet, partially restored both the gland and the marking behavior. Intact males, but not females, showed an attraction to sebum odors from the scent glands of strange conspecific males. This pattern of hormone control and responsiveness to sebum odors in M. tristrami is compared to that previously reported for Meriones unguiculatus , a related species.