Autacoids are naturally occurring substances that act as local hormones near their site of synthesis. The main classes of autacoids are amines, peptides, and lipids. Prostaglandins, histamine, bradykinin, and serotonin are some of the most important autacoids. They have various roles like mediating inflammation, vasodilation, gastric acid secretion, and neurotransmission. Their effects are mediated via receptors and they have therapeutic uses for conditions like inflammation, ulcers, and allergies.

2. Presented By: Experts
Member:-
 Aliyan Tariq
 Amna Arooj

3.  Autacoids are naturally occurring substances having
widely different structures and pharmacological
activities. The word autacoid comes from the Greek
“autos (self) and “akos” (medicinal agent, Cure or
remedy).
 These are biological factors which act like local hormones,
have a brief duration, act near the site of synthesis. They
have the common feature of being formed by tissues on
which they act, thus they function as local hormones.

4.  Amine Derived: These are derived from Natural
amino acids e.g. Histamine, Serotonin.
 Peptide Derived: Derived From Proteins and are made
up of long chains of amino acids e.g. Angiotensin,
Bradykinin
 Lipid Derived: Derived From Lipids e.g.
Prostaglandins, Interleukins

5. Following are the most important autacoids:
 Prostaglandins
 Histamine
 Bradykinin
 Serotonin

6.  The prostaglandins are a group of lipids made at sites of tissue
damage or infection that are involved in dealing with injury
and illness. They control processes such as inflammation, blood
flow, the formation of blood clots and the induction of labour.
Mechanism of Action:-
Prostaglandins get produced in the body via the fatty acid
“arachidonic acid”. Initially, arachidonic acid is created when the
enzyme phospholipase A2 cleaves the lipid diacylglycerol into the
molecule arachidonic acid. Cyclooxygenase enzymes then produce
prostaglandins from arachidonic acid via sequential oxidation of
each compound. The COX-1 enzyme produces basal amounts of
prostaglandins, while chemical mediators induce the COX-2
isoform to increase prostaglandins production. Prostaglandins are
highly lipophilic molecules that enter cells via a special
prostaglandin transporter called PGT (prostaglandin transporter).
There, they bind to prostaglandin receptors to exert their effects.

7. Theraputic uses:-
Abortion:-
Several of the prostaglandins used as abortifacients
(agents causing abortion). Prostaglandins have the
advantages of stimulating uterine contractions at
any stage of pregnancy.
Peptic Ulcer:-
Prostaglandins protect the mucous membrane of
stomach. Misoprostol is sometimes used to inhibit
the secretion of gastric acid.

8.  A prostaglandin antagonist is a hormone antagonist
acting upon one or more prostaglandins, a subclass of
eicosanoid compounds which function as signaling
molecules in numerous types of animal tissues.
 Nonselective Nonsteroidal anti-inflammatory drugs
(NSAIDs) are a group of chemically dissimilar agents
that act primarily by inhibiting the cyclooxygenase
(COX) enzymes, thus inhibiting the production of
prostaglandins in peripheral tissues. Examples are
aspirin, ibuprofen, naproxen, indomethacin, sulindac,
and piroxicam.

9.  Histamine is also an autacoid. It is a chemical
messenger that mediates a wide range of cellular
responses including allergic and inflammatory
reactions, gastric acid secretion and neurotransmission
in parts of the brain.
Mechanism of Action:-
Histamine binds with histamine receptors H1, H2, H3,
and H4. Where H1 and H2 receptors are widely expressed
and are targets of clinically useful drugs.

10. Therapeutic uses:-
Histamine is an important chemical that has a role
in a number of different bodily processes.
It stimulates gastric acid secretion, plays a role in
inflammation, dilates blood vessels, affects
muscle contractions in the intestines and lungs
and affects your heart rate.

11.  H1 Antihistamines:-
These compounds are H1 receptor blockers. They
do not influence the formation or release
of histamine. They only block the histamine
response at target tissue.
 H2 Antihistamine:-
These agents block the H2 histamine receptors.

12.  Therapeutic Uses of H1 Antihistamine:-
1. Allergic And Inflammatory Conditions: H1
receptor blockers are useful in treating allergies
caused by antigens.
2. Motion Sickness And Nausea: Along with the
antimuscarinic agents, H1 receptor blockers are
the most effective agents for prevention of the
symptoms of motion sickness, nausea.
3. Somnifacients: Many first generation
antihistamines have strong sedative properties
and are used in the treatment of insomnia.

13.  Therapeutic Uses of H2 Antihistamine:-
Histamine H2-receptor antagonists, also known
as H2-blockers or H2 Antihistamine, are used to
treat duodenal ulcers and prevent their return.
They are also used to treat gastric ulcers and for
some conditions, such as Zollinger-Ellison
disease, in which the stomach produces too much
acid.

14.  Bradykinin is a physiologically and pharmacologically
active peptide of the kinin group of proteins, consisting
of nine amino acids. It promotes inflammation.
Mechanism of Action:-
It mediates inflammation by causing vasodilation, by
increasing vascular permeability, and by stimulating the
synthesis of prostaglandins.

15.  Therapeutic Uses:-
Bradykinin is a potent endothelium-dependent
vasodilator and mild diuretic, which may cause
a lowering of the blood pressure. It also causes
contraction of non-vascular smooth muscle in the
bronchus and gut, increases vascular permeability
and is also involved in the mechanism of pain.

16.  A bradykinin B2 receptor antagonist used to
treat acute episodes of swelling and
inflammation associated with hereditary
angioedema (HAE).
 Production of bradykinin can be inhibited by
ecallantide, which acts on kallikrein, or by C1-
INH, which acts to inhibit formation of
kallikrein and HMW kininogen.

17.  Serotonin is a chemical that carries messages between nerve
cells in the brain and throughout your body. It is an
important neurotransmitter a local hormone in the gut.
Mechanism of Action:-
At rest, serotonin is stored within the vesicles of presynaptic
neurons. When stimulated by nerve impulses, serotonin is
released as a neurotransmitter into the synapse, reversibly
binding to the postsynaptic receptor to induce a nerve impulse
on the postsynaptic neuron. Serotonin can also bind to auto-
receptors on the presynaptic neuron to regulate the synthesis
and release of serotonin. Normally serotonin is taken back into
the presynaptic neuron to stop its action, then reused or broken
down by monoamine oxidase.

18.  Therapeutic Uses:-
Serotonin controls your mood and is responsible
for happiness. It helps regulate when you sleep
and wake, helps you think, maintains your mood,
and controls your desires.
It helps regulate attention, behavior and body
temperature.

19.  5-HT2A antagonists effectively block any
hallucinogenic action. So what LSD seems to
do is artificially activate serotonin receptors
when there is actually no serotonin being
released.
 Serotonin 5-HT3 receptor antagonists are
potent antiemetics that selectively block 5-HT3
receptors in the brain stem and in gastric wall
receptors that relay afferent emetic impulses
through the vagus nerve.