Biochemically, prostaglandins belong to the eicosanoids. This is a kind of preliminary stage of Arachidonic acid consisting of four times unsaturated fatty acids with 20 carbon atoms.
Their specialty lies in the mediation of pain, in the processes of inflammatory reactions and the development of fever.
Prostaglandins consist of several subgroups.
Prostaglandin E2 (PGE 2) should be emphasized here, as it has an important physiological importance as a local hormone, that is, as a tissue hormone.
The place of manufacture or biosynthesis of Eicosanoids, so that too Prostaglandins, runs in endoplasmic reticulum (ER) from a cell.
Prostaglandin E2 is especially when stimulated by inflammatory reactions by cells of the immune system, such as Macrophages or Monocytes, produced.
Also be immature Platelets (Platelets) stimulated differentiation and maturation by prostaglanidin E2.
With prostaglandins, signals are transmitted via special ones Membrane receptors (so-called G-protein-coupled receptors).
Prostaglandins come in entire organism in front. A particularly high number is found in sperm, i.e. in the secretion of the prostate, which led to the naming of the hormone.
Effects of prostaglandins
Prostaglandins primarily affect the so-called Second messenger system, a molecular exchange of messages between cells. That is why their effects in the organism are varied.
The different subgroups of prostaglandins have different effects.
in the Nervous system for example, prostaglandins are both inhibiting and promoting the conduction of excitation sympathetic nerve endings (Part of the autonomic nervous system, see: Sympathetic) involved.
Due to their chemical structure, prostaglandins are relative unstablewhich is of importance for their temporary effect.
Prostaglandins work on the one hand directlyas is the case with the contraction of the smooth muscles is the case, but on the other hand they fulfill their more important function indirectly as Hormone or Neurotransmitters.
This is where the effects of most drugs on prostaglandins come in. Since prostaglandins are involved in inflammatory processes and in the Fever and pain development are involved, one tries by means of so-called Cyclooxygenase inhibitors to intervene in the metabolism.
This leads to prostaglandin inhibition and thus alleviation of the symptoms.
Probably the best-known drug that works according to this principle is that Acetylsalicylic acid, known as aspirin.
Effect of prostaglandins in the kidney
Prostaglandin E2 (PGE2) is the most important prostaglandin in the kidney. It will be in the Renal cortex formed, however, that produces Renal medulla many times more at PGE2.
The physiologically most important function of PGE2 in the kidney is Vasodilatation and a Increase blood circulation.
PGE2 increases the release of the hormones Renin and Prostacyclin in the cells of the kidney corpuscles.
Renin is an important part of the Renin-Angiotensin-Aldosterone Systems (RAAS). This system largely regulates the Fluid and electrolyte balance of the organism and is therefore a central unit for regulating the Blood pressure.
But this can also lead to diseases. The so-called Bartter syndrome there is an increased secretion of prostaglandin E2 and thus a Overactivity of the RAAS described above.
Evidence of the formation of PGE2 in the kidney provides the Urine output.
It should also be noted that diseases such as a Heart failure or renal failure The blood flow to the kidney and thus its functional activity are severely restricted.
Because of a Inhibition of prostaglandin synthesisif affected patients for example Acetylsalicylic acid or diclofenac (NSAIDs), this functional restriction can be increased.
Effects of prostaglandins in the stomach
The individual subgroups of prostaglandins have different functions.
This is how it does it Prostaglandin E2 (PGE2) in the stomach definitely one protective function.
The mucous membrane cells of the stomach produce prostaglandin E2. The gastric mucus protects the stomach from the Stomach acid, whose production by PGE2 is inhibited.
This effect of PGE2 is basically based on three mechanisms:
The Blood flow to the gastric mucosa is greatly increased by PGE2, which is necessary for optimal functionality.
PGE2 reduces gastric acid secretion through the Parietal cells the stomach wall.
Adjoining cells produce mucus in the stomach. This mucus secretion is increased by PGE2.
These three mechanisms explain that drugs like Acetylsalicic acid (please refer: aspirin) due to increased consumption Bleeding in the stomach, or. Ulcers (Stomach ulcers) being able to lead.
Acetylsalicylic acid is one Cyclooxygenase 1 inhibitors (COX1 inhibitor), which restricts or prevents the protective function of the prostaglandins.
Prostaglandins at birth
One way, one To initiate childbirth, consists in the administration of different prostaglandins. There are various ways of administering this.
For example, prostaglandins can be used locally in the form of a gel or administered as a tablet (technical term: Priming).
The Onset of action (Induction of childbirth) usually takes two to three hours. As a result of the administration of prostaglandins, the cervix becomes more flexible and softer.
Whether a gynecologist should perform this method is often based on the so-called Bishop Scores determined (an assessment based on measurable anatomical factors such as the Cervical width goes out).
A small but relevant difference is in the type of prostaglandin used.
There are so-called Prostaglandin E1 analogues and Prostaglandin E2 analogues.
One of the main differences between prostaglandin E1 and E2 analogues is that there is one Prostaglandin E1 Analogue (e.g. Misoprostol) is usually used orally, it is cheaper and there is more frequent overstimulation of the uterus (also known as a contraction storm). This will Prostaglandin E1 often perceived as the more unpleasant option.
In addition, it must not be used after operations on the uterus.
Prostaglandins and eye drops
Also in the Ophthalmology prostaglandin analogs have an area of application. They are used to treat Wide angle glaucoma and one increased pressure in the eye (Glaucoma, Green Star) used.
Side effectsThe information contained in the package insert includes local defense reactions in the form of reddening of the eye, pigmentation of the iris and changes in the area of the eyelashes (thickness, number, length).
It is not advisable to use these eye drops during pregnancy to be used, as otherwise the birth could be initiated early.
Some patients also complain when they take certain medications Side effectsthat the affect the entire organism. This can manifest itself in a decreased skin irritation threshold, rash (especially on the palms of the hands), sweating, fear, tremors, insomnia and increased dreaming.