Commonly Used Antidepressants May Also Affect Human Immune System

[Guest guest]

Commonly Used Antidepressants May Also Affect Human Immune System

Washington, D.C. -- Drugs that treat depression by manipulating the

neurotransmitter serotonin in the brain may also affect the user's

immune system in ways that are not yet understood, say scientists from

town University Medical Center and a Canadian research institute.

Thats because the investigators found, for the first time, that

serotonin is passed between key cells in the immune system, and that the

chemical is specifically used to activate an immune response. They do

not know yet, however, whether these SSRI (selective serotonin reuptake

inhibitors) drugs - including the brands Prozac, Zoloft, Paxil and

others could have either a beneficial or a damaging effect on human

immunity.

The wider health implication is that commonly used SSRI antidepressants,

which target the uptake of serotonin into neurons, may also impact the

uptake in immune cells, said Gerard Ahern, Ph.D., assistant professor of

Pharmacology at town and lead researcher on the study.

He said that while it may be possible that SSRI drugs may restore a

healthy immune function in people who are depressed and prone to

infections, it is possible that they might also bolster immunity to the

point that they trigger autoimmune disease. At this point we just don't

know how these drugs might affect immunity, so we really need to clarify

the normal role of serotonin in immune cell functioning, Ahern said.

[ No one wants to bite the hand that feeds them. Universities make

millions of dollars a year doing clinical trials and drug companies

give millions to med schools. This issue wil disappear off the radar

screen in a few days and you'll never hear anything about it again. --

]

The surprising finding that serotonin is rapidly passed between immune

cells in a manner similar to its transmission between brain neurons was

revealed in mid-October, when the research team published the findings

in the journal Blood. In December, the discovery was highlighted for the

general scientific audience by the journal Nature Reviews Immunology,

and now the research team is working to produce an animal model that may

help describe the precise nature of this interaction.

[This is " surprising " to only these researchers. This information

has been available since THE 1980's. See the abstract of the article,

" Role of Serotonin in the Immune System and in Neuroimmune

Interactions " , I've appended at the end of this news article.

--]

The novelty is that we reveal a potential communication, involving the

transmitter serotonin, between immune cells that is normally only found

between neurons, Ahern said.

In addition to Ahern, Peta O'Connell, Ph.D., from the Robarts Research

Institute in Canada, was also a co-lead researcher on the study.

Scientists from the Robarts Research Institute also contributed to the

work.

In the brain, serotonin transmission between neurons is associated with

feelings of pleasure, mood, and appetite, and the class of

antidepressants known as SSRIs keeps serotonin active within the

synaptic spaces between neurons, enhancing the chemical's positive

effects. Unlike in the brain, which uses chemical messengers to

communicate between nerve cells, the immune system is believed to

converse through physical contact -- one type of immune cell touches

another, setting off a response.

Specifically, antigen presenting cells display their antigens (bits of a

foreign invader) to T-cells, and a resulting physical coupling between

the antigens and the T-cells will prompt the T-cells to divide and

expand in population, triggering an immune response designed to destroy

the invader. This process may take hours.

What the town researchers found, however, is that dendritic cells

-- the most powerful of the antigen-presenting cells and the ones that

can find invaders that have never infected the body and educate the

immune system to fight them -- also use serotonin to quickly excite a

T-cell response. They discovered that these dendritic cells can rapidly

secrete serotonin, which activates serotonin receptors on certain types

of T-cells.

In addition to the physical contact, it surprised us to find that these

immune cells also have machinery to take up serotonin and to secrete it

in an excitatory manner, Ahern said. The point behind this transmission

is not entirely clear, but it appears to be an additional way of

stimulating a T cell response.

Drugs that block serotonin reuptake likely change some of the parameters

of T-cell activation, but we don't know yet if it enhances or inhibits

the total immune response, Ahern said. But it is something that should

be explored because we really have no idea what SSRIs are doing to

people's immune systems.

For a copy of the study or an interview with Dr. Ahern, please contact

Cavender at lsc6@... .

==================================================

ABSTRACT

Role of Serotonin in the Immune System and in Neuroimmune Interactions

Authors: Mössner R.; Lesch K-P.

Source: Brain, Behavior, and Immunity, Volume 12, Number 4, December

1998, pp. 249-271(23)

Publisher:Academic Press

Serotonin (5-HT) is one of the most extensively studied

neurotransmitters of the central nervous system. 5-HT is, however,

also present in a variety of peripheral tissues including in

constituents of the immune system. The function of 5-HT in the immune

system has received increasing attention since about 1984, but has

been reviewed only once, in 1985. In recent years, modern techniques

of molecular biology such as reverse-transcriptase polymerase chain

reaction and targeted gene disruption have made it possible to study

new important aspects of 5-HT in the immune system. In the first part

of the review, we explore whether 5-HT is involved in interactions

between the central nervous and immune systems. It emerges that 5-HT

may mediate interactions of these two systems by four different

pathways. In the second part, we dissect the functional roles of 5-HT

in the immune system. We describe the distribution of 5-HT receptors

and the 5-HT transporter on immune cells and estimate which levels

5-HT may attain in the extracellular space in physiological conditions

and under pathological circumstances such as inflammation, thrombosis,

and ischemia. At these 5-HT concentrations, four major functions for

5-HT emerge. These include T cell and natural killer cell activation,

delayed-type hypersensitivity responses, production of chemotactic

factors, and natural immunity delivered by macrophages. Finally, we

discuss promising future avenues to further advance knowledge of the

role of 5-HT in the immune system and in neuroimmune interactions.

Copyright 1998 Academic Press.

--

Regards,

[Guest guest]

so your immunity in the future could be changed? that may be why i

still have the problems with the burning?

thank you

jason

>

> Commonly Used Antidepressants May Also Affect Human Immune System

>

> Washington, D.C. -- Drugs that treat depression by manipulating the

> neurotransmitter serotonin in the brain may also affect the user's

> immune system in ways that are not yet understood, say scientists

from

> town University Medical Center and a Canadian research

institute.

>

> Thats because the investigators found, for the first time, that

> serotonin is passed between key cells in the immune system, and

that the

> chemical is specifically used to activate an immune response. They

do

> not know yet, however, whether these SSRI (selective serotonin

reuptake

> inhibitors) drugs - including the brands Prozac, Zoloft, Paxil and

> others could have either a beneficial or a damaging effect on human

> immunity.

>

> The wider health implication is that commonly used SSRI

antidepressants,

> which target the uptake of serotonin into neurons, may also impact

the

> uptake in immune cells, said Gerard Ahern, Ph.D., assistant

professor of

> Pharmacology at town and lead researcher on the study.

>

> He said that while it may be possible that SSRI drugs may restore a

> healthy immune function in people who are depressed and prone to

> infections, it is possible that they might also bolster immunity

to the

> point that they trigger autoimmune disease. At this point we just

don't

> know how these drugs might affect immunity, so we really need to

clarify

> the normal role of serotonin in immune cell functioning, Ahern

said.

>

> [ No one wants to bite the hand that feeds them. Universities

make

> millions of dollars a year doing clinical trials and drug companies

> give millions to med schools. This issue wil disappear off the

radar

> screen in a few days and you'll never hear anything about it

again. --

> ]

>

> The surprising finding that serotonin is rapidly passed between

immune

> cells in a manner similar to its transmission between brain

neurons was

> revealed in mid-October, when the research team published the

findings

> in the journal Blood. In December, the discovery was highlighted

for the

> general scientific audience by the journal Nature Reviews

Immunology,

> and now the research team is working to produce an animal model

that may

> help describe the precise nature of this interaction.

>

>

> [This is " surprising " to only these researchers. This

information

> has been available since THE 1980's. See the abstract of the

article,

> " Role of Serotonin in the Immune System and in Neuroimmune

> Interactions " , I've appended at the end of this news article.

> --]

>

> The novelty is that we reveal a potential communication, involving

the

> transmitter serotonin, between immune cells that is normally only

found

> between neurons, Ahern said.

>

> In addition to Ahern, Peta O'Connell, Ph.D., from the Robarts

Research

> Institute in Canada, was also a co-lead researcher on the study.

> Scientists from the Robarts Research Institute also contributed to

the

> work.

>

> In the brain, serotonin transmission between neurons is associated

with

> feelings of pleasure, mood, and appetite, and the class of

> antidepressants known as SSRIs keeps serotonin active within the

> synaptic spaces between neurons, enhancing the chemical's positive

> effects. Unlike in the brain, which uses chemical messengers to

> communicate between nerve cells, the immune system is believed to

> converse through physical contact -- one type of immune cell

touches

> another, setting off a response.

>

> Specifically, antigen presenting cells display their antigens

(bits of a

> foreign invader) to T-cells, and a resulting physical coupling

between

> the antigens and the T-cells will prompt the T-cells to divide and

> expand in population, triggering an immune response designed to

destroy

> the invader. This process may take hours.

>

> What the town researchers found, however, is that dendritic

cells

> -- the most powerful of the antigen-presenting cells and the ones

that

> can find invaders that have never infected the body and educate the

> immune system to fight them -- also use serotonin to quickly

excite a

> T-cell response. They discovered that these dendritic cells can

rapidly

> secrete serotonin, which activates serotonin receptors on certain

types

> of T-cells.

>

> In addition to the physical contact, it surprised us to find that

these

> immune cells also have machinery to take up serotonin and to

secrete it

> in an excitatory manner, Ahern said. The point behind this

transmission

> is not entirely clear, but it appears to be an additional way of

> stimulating a T cell response.

>

> Drugs that block serotonin reuptake likely change some of the

parameters

> of T-cell activation, but we don't know yet if it enhances or

inhibits

> the total immune response, Ahern said. But it is something that

should

> be explored because we really have no idea what SSRIs are doing to

> people's immune systems.

>

> For a copy of the study or an interview with Dr. Ahern, please

contact

> Cavender at lsc6@... .

>

> ==================================================

> ABSTRACT

>

> Role of Serotonin in the Immune System and in Neuroimmune

Interactions

> Authors: Mössner R.; Lesch K-P.

>

> Source: Brain, Behavior, and Immunity, Volume 12, Number 4,

December

> 1998, pp. 249-271(23)

>

> Publisher:Academic Press

>

>

> Serotonin (5-HT) is one of the most extensively studied

> neurotransmitters of the central nervous system. 5-HT is, however,

> also present in a variety of peripheral tissues including in

> constituents of the immune system. The function of 5-HT in the

immune

> system has received increasing attention since about 1984, but has

> been reviewed only once, in 1985. In recent years, modern

techniques

> of molecular biology such as reverse-transcriptase polymerase chain

> reaction and targeted gene disruption have made it possible to

study

> new important aspects of 5-HT in the immune system. In the first

part

> of the review, we explore whether 5-HT is involved in interactions

> between the central nervous and immune systems. It emerges that 5-

HT

> may mediate interactions of these two systems by four different

> pathways. In the second part, we dissect the functional roles of 5-

HT

> in the immune system. We describe the distribution of 5-HT

receptors

> and the 5-HT transporter on immune cells and estimate which levels

> 5-HT may attain in the extracellular space in physiological

conditions

> and under pathological circumstances such as inflammation,

thrombosis,

> and ischemia. At these 5-HT concentrations, four major functions

for

> 5-HT emerge. These include T cell and natural killer cell

activation,

> delayed-type hypersensitivity responses, production of chemotactic

> factors, and natural immunity delivered by macrophages. Finally, we

> discuss promising future avenues to further advance knowledge of

the

> role of 5-HT in the immune system and in neuroimmune interactions.

> Copyright 1998 Academic Press.

>

>

>

> --

> Regards,

>

>