Reproductive suppression

Control of parasitic invasions has been successfully achieved with compounds that inhibit key enzymes in pathways vital to the biosynthesis of the building blocks of nucleic acids in these pathogenic microorganisms. This results in their reproductive suppression or death. An alternative mechanism can also exist, particularly if the inhibitor has a close chemical similarity to the enzyme s normal substrate (metabolite). Such an analog compound may still be affected by the enzyme, resulting in a false structural component, which if incorporated into the essential biopolymer at all, will lead to nonfunctioning (or errant) DNA or RNAs. Such drugs are referred to as antimetabolites. They... 

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. 

Brant, C. L. 1995. A mechanistic examination of reproductive suppression in the cooperatively breeding pine vole Microtus pinetorum). Master s thesis. Miami University, Oxford, OH. 

The results of studies on pheromonal suppression of sexual development in house mice and several species of voles permit some speculation on the possible correlation between pheromonal mechanisms and habitat utilization (Table 2). In a preliminary attempt to relate habitat parameters to pheromonal systems, it appears that reproductive suppression by family chemosignals correlates with a stable and continuous habitat type. Batzli et al. 

Table 2. Speculations on the relationship between type of reproductive suppression and habitat type in selected rodents. 

Species Reproductive Suppression Habitat Time Space... 

In addition to their endocrine disrupting properties, it must be appreciated that many of the chemicals in question possess more general toxic properties, which may be potentiated by metabolism by the organism. Several PAHs, PCBs and PCDDs are carcinogenic, while certain phthalate esters can enhance the excretion of zinc, potentially leading to zinc deficiency. Zinc, an essential element, plays a vital role in spermatogenesis and mature T-cell production. Deficiency may result in abnormalities of the male reproductive system, depletion of spermatogenesis and suppression of the immune system. 

The cytokine leptin is secreted by adipocytes (fat cells) in proportion to the size of the adipose dq>ot and circulates via the bloodstream to the brain, where it ultimately affects feeding behavior, endocrine systems including reproductive function and, at least in rodents, energy expenditure. The major effect of Lqrtin is on the hy-pothalamous, where it suppresses appetite and hence food intake. Leptin exerts its effects via binding to the leptin receptor in the brain (specifically in the hypothalamus), which activates the JAK-STAT Pathway. 

Harazene A, Ema M (2003) Suppression of decidual cell respense induced by dibutyltin dichloride in pseudopregnant rats as a cause ef early embryenic loss. Reproductive Toxicology, 17(4) 393-399. 

Sequences of aggressive behavior that are composed of characteristic acts and postures following each other rapidly are disrupted. These disorganizing effects parallel the analysis of amphetamine effects on other intricately patterned behaviors such as feeding, maternal care, play behavior, or reproductive interactions. For example, amphetamine suppresses play... 

Barrett J., Abbott D. and George L. (1993). Sensory cues and the suppression of reproduction in subordinate female marmoset monkeys, Callithrix jacchus. J Reprod Fertil 97, 301-310. 

Faulkes C.G. and Abbott D.H. (1993). Evidence that primer pheromones do not cause social suppression of reproduction in male and female Naked Mole Rats (H. glaber). J Reprod Fertil 99, 225-230. 

McClintock M. (1983). Pheromomal regulation of the ovarian cycle enhancement, suppression and synchrony. In Pheromones and Reproduction in Mammals (Vandenberg J.G., ed.). Academic Press, New York, pp. 113-150. 

Species targeted by pesticides usually make up only several tenths of a percent of the total number of species in an agricultural environment. Natural enemies and parasites usually decrease a species mass reproduction reliably. Destroying, or sharply decreasing the number of, such enemies through pesticide use often leads to a population explosion in the suppressed species chemical protection thus creates a greater threat to the protected cultivars [1]. 

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