Urine reproductive activation

For our purposes, oaks are important because they drop the acorns that determine how many white-footed mice successfully withstand the harsh winter months. Before winter arrives, however, a multitude of other factors has influenced the number of mice available to gather the acorns. One of these factors is the mice s reproductive activity, and this happens to be under the influence of some peculiar pheromones. Because they contribute to determining the number of mice, these chemicals also enter our story. They are airborne signals present in adult-mouse urine that affect the maturation and reproductive success of young female mice. 

The VNO is extremely important in mediating endocrine responses to primer pheromones. Puberty acceleration in female rats by male urine odors can be prevented by electrolytic damage to the vomeronasal nerve. Also, effects of male urine odor such as shortening of the estrus cycle (see Ch. 8) can be eliminated by section of the vomeronasal nerve, or bilateral electrocoagulation of the accessory olfactory bulb (Sanchez-Criado, 1982). In rats, the odor of males stimulates ovulation in females, an effect that is lost if the VNO is extirpated (Johns etal., 1978). Female prairie voles, M. ochrogaster, respond to odors from males with reproductive activation. Surgical removal of the VNO from adult females impedes this reproductive activation by the stud male. The weights of the uterus and the ovaries of these females were lower than those of normal or sham-operated individuals. However, the females without a VNO were still able to locate food by chemical cues (Lepri and Wysocki, 1987). 

Male and female dominance is associated with reproductive success (e.g. Chovnick, Yasukawa, Monder Christian, 1987). Furthermore, urine has been shown to act as a vehicle for pheromones which regulate the reproductive activity of young females (Drickamer, 1982 Jemiolo, Gubemick, Yoder Novotny, 1994 Rozenfeld Denoel, 1994). The second hypothesis of the present study predicts that, in female groups of common voles, only the dominant female will reproduce, while subordinate females will remain reproductively suppressed, due to the release of relevant pheromones excreted in the urine of the dominant female. 

In the present study, I have indirectly investigated the existence of hierarchies in groups of female common voles on the basis of their urine marking behavior and reproductive activity. 

Mice are able actively to seek or avoid priming pheromones that modulate their ovarian cycle and onset of puberty. Peripubertal female mice avoid the urine odor of adult males, known to accelerate puberty in females, and are more attracted to the odor of grouped adult females. This behavior is particularly effective because the active space of the (almost) non-volatile male pheromone is small, and prolonged exposure is required for the effect to occur (Coppola and O Connell, 1988). Likewise, prepubertal female mice do not urinate near urine marks of adult males, while grouped, estrous, and diestrous adult females do. Such behavior may help young females to avoid exposure to male odors until they reach puberty. This way they would be protected from mating too early, and their eventual reproductive success would be enhanced (Drickamer, 1989a). 

In other rodents, subordinate males also smell scent marks quite often and so keep informed on the presence, status and activities of higher-ranking group members. For instance, dominant males of the hispid cotton rat, Sigmodon hispidus, urine mark more than subordinates. The social status of the male urine donor affects the response of other males to the odor. The response of a reproductive female to feces of either sex depends on her dominance status (Gregory and Cameron, 1989). 

Urine and feces odors of mink applied to soil and vegetation in outdoor enclosures had no effect on gray-tailed voles, Microtus canicaudus, in Oregon. The voles did not seek taller vegetation for cover, and their reproduction was not affected. Specifically, reproductive rates, time to sexual maturation, juvenile recruitment, and activity did not change after exposure to mink odors (Wolff and Davis-Born, 1997). 

OSHA PEL TWA 0.5 mg(As)/m3 ACGIH TLV BEI 35 (As)/L inorganic arsenic and methylated metabolites in urine DOT CLASSIFICATION 6.1 Label Poison SAFETY PROFILE Poison by an unspecified route. Moderately toxic by ingestion and intraperitoneal routes. Experimental teratogenic and reproductive effects. A skin and eye irritant. Questionable carcinogen with experimental tumorigenic data. Mutation data reported. Used as an herbicide, defoliant, and silvicide. Hazardous when water solution is in contact with active metals, e.g., Fe, Al, Zn. When heated to decomposition it emits toxic fumes of As. 

SAFETY PROFILE Human poison by intramuscular route. Experimental poison by intramuscular, intraperitoneal, subcutaneous, and intravenous routes. Mildly toxic by ingestion. An experimental teratogen. Human systemic effects by intramuscular route convulsions or effect on seizure threshold, change in motor activity, change in kidney tubules, and urine volume decrease or anuria. Experimental reproductive effects. Used as an antibiotic. When heated to decomposition it emits very toxic fumes of NOx, SOx, and Na20. 

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