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HORMON LOKAL(Dr. I Dewa Ayu Susilawati, drg. M. Kes)

Tujuan

Setelah mempelajari bab ini, anda diharapkan

mampu:

1. Menjelaskan pengertian hormon lokal

2. Menjelaskan jenis-jenis hormon lokal3. Menjelaskan mekanisme kerja hormon lokal

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Target sel hormon lokal berada di jaringan atau

sel di sekitar sekretori sel

* Hormone parakrin : target sel di sekitar sel

sekretori

* Hormon autokrin disekresi suatu sel dan

aksinya mempengaruhi sel itu sendiri.

* Sedangkan juxtakrin adalah jenis komunikasi

interselular yang melibatkan sel-sel yang

letaknya berdempetan.

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Beberapa jenis hormon lokal

- Autokoids: bradikinin, histamin, prostaglandin

(berperan pada reaksi inflamatori)

- Neurotransmiter- Sitokin

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Bradykinin is a peptide that causes blood

vessels to enlarge (dilate), and therefore

causes blood pressure to lower. A class of drugs called ACE inhibitors, which are used to

lower blood pressure, increase bradykinin (by

inhibiting its degradation) further loweringblood pressure. Bradykinin works on blood

vessels through the release of prostacyclin,

nitric oxide, and Endothelium-Derived

Hyperpolarizing Factor.

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Histamine is an organic nitrogen compound involved

in local immune responses as well as regulating

physiological function in the gut and acting as aneurotransmitter.[1] Histamine triggers the

inflammatory response. As part of an immune

response to foreign pathogens, histamine is

produced by basophils and by mast cells found innearby connective tissues. Histamine increases the

permeability of the capillaries to white blood cells

and other proteins, in order to allow them to engage

foreign invaders in the infected tissues.[2] It is found

in virtually all animal body cells

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Prostaglandin is any member of a group of lipid 

compounds that are derived enzymatically from fatty

acids and have important functions in the animal body. Every prostaglandin contains 20 carbon atoms,

including a 5-carbon ring.

• They are mediators and have a variety of strong

physiological effects, such as regulating thecontraction and relaxation of smooth muscle

tissue.[1] Prostaglandins are autocrine or paracrine,

which are locally acting messenger molecules.

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Neurotransmitters: chemical released by neurons

to stimulate neighbouring neurons, allowingimpulses to be passed from one cell to the next

throughout the nervous system. A nerve impulse

arriving at the axon terminal of one neuron

stimulates release of a neurotransmitter, whichcrosses the microscopic gap (see synapse) in

milliseconds to the adjoining neuron's dendrite.

Many chemicals are believed to act as

neurotransmitters. The few that have been identifiedinclude acetylcholine, dopamine, and serotonin.

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Cytokines (Greek cyto-, cell; and -kinos,

movement) are small cell-signaling protein 

molecules that are secreted by the glial cells 

of the nervous system and by numerous cells

of the immune system and are a category of 

signaling molecules used extensively in

intercellular communication. Cytokines can beclassified as proteins, peptides, or

glycoproteins; the term "cytokine"

encompasses a large and diverse family of regulators produced throughout the body by

cells of diverse embryological origin.

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- limfokin diproduksi limfosit

- interleukin komunikasi antar lekosit

- sitokin

diproduksi oleh berbagai selContoh sitokin:

- Interleukin

- TNF alfa- Interferon gama

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Interleukins are a group of cytokines (secreted

proteins/signaling molecules) that were first seen to be

expressed by white blood cells (leukocytes). The term

interleukin derives from (inter-) "as a means of communication", and (-leukin) "deriving from the fact that

many of these proteins are produced by leukocytes and act on

leukocytes". The name is something of a relic though (the

term was coined by Dr. Paetkau, University of Victoria); it has

since been found that interleukins are produced by a wide

variety of body cells. The function of the immune system 

depends in a large part on interleukins, and rare deficiencies

of a number of them have been described, all featuring

autoimmune diseases or immune deficiency. The majority of interleukins are synthesized by helper CD4+ T lymphocytes, as

well as through monocytes, macrophages, and endothelial

cells. They promote the development and differentiation of T,

B, and hematopoietic cells.

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Tumor necrosis factor (TNF, cachexin or cachectin and

formerly known as tumor necrosis factor-alpha) is a

cytokine involved in systemic inflammation and is amember of a group of cytokines that stimulate the

acute phase reaction.

• The primary role of TNF is in the regulation of 

immune cells. TNF is able to induce apoptotic cell

death, to induce inflammation, and to inhibit

tumorigenesis and viral replication. Dysregulation of 

TNF production has been implicated in a variety of human diseases, as well as cancer.

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Interferon-gamma (IFN-γ) is a dimerized soluble

cytokine that is the only member of the type II class

of interferons.

[2]

This interferon was originally calledmacrophage-activating factor, a term now used to

describe a larger family of proteins to which IFN-γ

belongs.

• IFN-γ, or type II interferon, is a cytokine that is criticalfor innate and adaptive immunity against viral and

intracellular bacterial infections and for tumor

control. Aberrant IFN-γ expression is associated with

a number of autoinflammatory and autoimmune 

diseases