Reproductive system, prostaglandins

Prostaglandins are fatty acid derivatives that are even more powerful biochemical regulators than steroids. They are called prostaglandins because they were first isolated from secretions of the prostate gland. They were later found to be present in all body tissues and fluids, usually in minute quantities. Prostaglandins affect many body systems, including the nervous system, smooth muscle, blood, and the reproductive system. They play important roles in regulating such diverse functions as blood... 

The prostaglandins occur in all tissues but in very small amounts. They act on loci in the same cells as those in which they are synthesized, and their biological roles are diverse e.g., they function in the female reproductive system during ovulation, menstruation, pregnancy, and parturition, and they stimulate uterine muscle contraction. 

Concentrations outside the reproductive system are generally much lower. Karim, Hillier and Devlin have carried out systematic surveys of the distribution of PGs El, E2, F15, F2a in a wide variety of tissues in man [31] (Table 7.1 and in six widely used laboratory animals [32] (Table 7.2). In the majority of cases one or more of these prostaglandins was present in varying amounts, with PGE2 and PGp2 occurring most commonly. 

Effects of prostaglandins on the reproductive system of rhesus monkeys are similar to those found in hvunans (e.g. relative potency of PGE2 vs. PGF, resistance to termination of pregnancy during the second trimester of pregnancy, total amounts of PC s necessary to initiate myometrial contractions.) Hence the rhesus monkey is a reasonably good animal model for basic research. 

In fish reproduction, the best-investigated pheromone system is that of the goldfish [Carassius auratus). Here, sex steroids and prostaglandins play important roles. The female produces two pheromones sequentially a preovulatory primer pheromone and a postovulatory prostaglandin pheromone that act on the male. 

The prostaglandins and thromboxanes have major effects on four types of smooth muscle airway, gastrointestinal, reproductive, and vascular. Other important targets include platelets and monocytes, kidneys, the central nervous system, autonomic presynaptic nerve terminals, sensory nerve endings, endocrine organs, adipose tissue, and the eye (the effects on the eye may involve smooth muscle). 

DHA, C22 6 i 3 cis-,cis-,cis-, cA-,cA-,cA-4,7,10,13,16,19-Docosahexaenoic acid). Essential fatty acids support the cardiovascular, reproductive, immune, and nervous systems, including the production of prostaglandins, which regulate body functions such as heart rate, blood pressure, blood clotting, fertility, and conception, and they are essential in the inflammatory response. 

The prostaglandins as a group are known for having extremely short life span, sometimes as short as several minutes within an organism before enzymatic action breaks them down. They are produced on demand, and act in very small amounts to regulate the nervous, respiratory, cardiovascular, reproductive, endocrine, immunological, and renal systems. 

Olfaction, the sense of smell, is an important neural system in various animal species, including fish, for their life. Fish can detect a variety of odorants emitted from objects and dissolved in the water, such as amino acids, bile salts, nucleotides, polyamines, prostaglandins, and steroids. The fish olfactory system is extensively developed to receive and discriminate these odorant molecules, to transmit their signals to the brain, and to mediate fundamental behaviors such as food finding, alarm response, predator avoidance, social communication, reproductive activity, and spawning migration (Sorensen and Caprio 1998 Zielinski and Hara 2007). 

By contrast with their effects on gastrointestinal and reproductive smooth muscle, prostaglandins usually relax smooth muscle of the respiratory system. This has been studied in vitro using isolated tracheal preparations of the cat, monkey, rabbit, guinea-pig and ferret where PGEi showed activity in concentrations as low as 1 ng/ml [198, 201, 264]. With species where tracheal smooth muscle does not exhibit inherent tone (for example, cat, monkey and rabbit) the effect of PGEi can be demonstrated after a sustained contraction has first been produced by a suitable agent sudi as acetylcholine. 

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