Rodents male marking

Conspecific secretions and excretions may stimulate pest rodents to consume bait. An example is the metad, or soft-furred rzt, RattusmeltadapalUdior, of the grasslands and crop fields of India. In a laboratory test, 1% conspecific urine from males or females added to the diet of millet increased food consumption by 32 to 70%. The metads also stayed longer in the half of the cage with the urine-treated food than in that with untreated food, and scent marked more there. The males marked with sebum, the females with urine. Male urine tended to be more effective, and males responded more than females (Soni and Prakash, 1987). 

A number of the observed renal effects of Stoddard solvent are consistent with a mechanism which appears to be unique to male rats. Male rodents scent mark their territories with pheromones... 

Nicotine is unique in causing upregulation of nAChRs following chronic treatment in male rats. In rodents, chronic nicotine administration increases nicotinic receptor sites in several brain regions (Marks et al. 1985 Schwartz and Kellar 1983 Ksir et al. 1987) and this upregulation corresponds to the sensitization... 

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). 

FIGURE 8.4 The Bronson model of priming pheromone actions in rodents. Chemical signaling between males and females constitutes a feedback mechanism that results in accelerated maturation and reproduction. This, in turn, permits the mice to adjust their reproduction and population size quickly to respond to environmental conditions such as sudden food abundance at harvest time. FSH, follicle-stimulating hormone LH, luteinizing hormone PRL, prolactin. Stimulation and inhibition are marked by - - and —, respectively. (From Bronson and Coquelin, 1980.)... 

There occur marked differences between rodent species and humans in the proportions of a dose excreted as these various major metabolites, and the dose size introduces further variables. Mr et al. (1989) gave male Sprague-Dawley rats, BALB/c mice and Syrian hamsters 0.1,0.7 and 7 mmol/kg bw dimethylformamide (approximately 7,50 and 500 mg/kg bw) by intraperitoneal injection and collected urine for 60 h (rat), 24 h (mice) and 36 h (hamster). In all cases, dimethylfonnamide and AMCC were very minor urinary metabolites, while the amounts of substances analysed as W-methylformamide ... 

Postweaning CR (weight was 50% of AL rats) from 21 days of age in female rats markedly delays pubertal onset. All AL rats reach puberty by 45 days of age, but only 10% of CR rats do so by 80 days [58]. Similar conclusions are found for puberty onset in male rats [59], but the susceptibility of pubertal development to CR appears to be greater in female than male rodents [60],... 

In the T-maze we can test the responses of a male or female to a urine mark of the opposite sex, or from dominant or subordinate individuals of the same sex, or some other difference of interest. Among the many studies using two-way choice apparatuses for mice, a good example is a paper by Krasnov and Khokhlova (1996) that deals with mice responding to odors of another rodent species. We will test responses of males and females to urine of the same and different sex in a two-way choice apparatus (T-Maze). 

Retrospective analyses of cUnical studies suggest that females are more susceptible to aminoglycoside nephrotoxicity than males [17]. This is in contradiction to the increased susceptibility of male rodents to aminoglycosides [21]. In experimental animals with strep-tozotocin diabetes, nephrotoxicity and renal drug uptake are markedly reduced [22, 23]. There seems to be no clinical counterpart to this experimental observation. 

Laboratory mice have been used as the model rodent to demonstrate the potential of aversive social odors to manage populations. Chemical constituents in the urine of dominant male mice have been shown to inhibit the exploratory behaviour of subordinate mice in laboratory-based arena studies. Two constituents, a and P-famesene, have been patented as mouse repellents (Novotny, Harvey Jemiolo, 1993). However, we do not know what effect these chemicals have on free-living rodent populations, where dominance hierarchies may not always exist. The scent marks left by dominant male rats within family groups appear to act not so much as warning signals for strange rats, but as aids to orientation (Lund, 1975). In the context of controlling rat populations, social odors are unlikely to produce the immediate reduction in numbers required to control a troublesome rat... 

Volatile constituents associated with female urine and/or vaginal discharge often increase male and female sexual activity (271-279). Urinary marking of the environment is also an important feature of rodent and primate behavior (270, 280, 281). The compounds found in the urine of males and females generally vary with the breeding season or with the physiological status of the females this has been observed in the ram (274), red fox (282), the goat (283, 284), and the wolf (285). 

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