Is it true, that Stips (hot spicy chicken pieces) in KFC (Ketucky
Fried Chicken) can contain substance that one can be dependent on?

I have not (so far) managed to find any reports that specific
additives used in KFC products are associated with dependency, per se.

BUT, there is controversial new evidence that so-called "junk food",
including KFC, may be addictive in itself.  It's suggested that fatty
and/or sugary foods cause changes in brain chemistry, similar to those
seen in addiction.

Here are some news reports:

http://www.telegraph.co.uk/news/main.jhtml?xml=%2Fnews%2F2003%2F01%2F30%2Fwfood30.xml

http://www.telegraph.co.uk/news/main.jhtml?xml=%2Fnews%2F2003%2F01%2F30%2Fwfood30.xml

Also bear in mind that virtually anything can become an addiction, in
a small minority of people.  So if you name any food, you would
probably be able to find someone, somewhere, who is "addicted" to it,
even if it has no known habit-forming ingredient.  In such cases, the
addiction is psychological, not chemical, in origin (i.e. it's more of
a compulsion, than an addiction), and might be broken with the help of
certain types of psychotherapy, or with drugs prescribed for Obsessive
Compulsive Disorder - OCD).

yes, as peppers and chillies contain capsaicin ....

 It is said that the burning sensation from capsaicin is addictive. It
is also said that one becomes ?conditioned? to this sensation. The
reason is that during the eating of chiles, a chemical in the chile
pepper called Capsaicin, irritates the trigeminal cells. These are
pain receptor cells located throughout the mouth, the nose and the
throat. When your body's nerves feel the pain induced by the chemical
on these cells, they immediately start to transmit pain messages to
your brain. Your brain receives these signals and responds by
automatically releasing endorphins (the body's natural painkiller).
These endorphins kick in and act as a painkiller and at the same time,
create a temporary feeling of euphoria, giving the chile pepper eater,
a natural high.
The body's other responses include increasing the heart rate to
increase the metabolism, increasing salivation in order to try and
refresh the mouth and by increasing the rate of sweating by the body.
Your nose also starts to run and the gastrointestinal tract slips into
high speed. Hot & spicy food lovers soon begin to crave these feelings
and are soon hooked.

....now, I'm off to KFC for another big ole platter