Recettore oppioidi mu, K, Delta

Recettore oppioidi mu, K, Delta
(pre e post sinaptico)
LIGANDE
(pre e post sinaptico)
Recettore oppioidi mu, K, Delta
Endocitosi
Apoptosi
riciclo
Recettore oppioidi mu, K, Delta
Endocitosi
Apoptosi
riciclo
la maggioranza dei endo-peptidi
oppioidi subisce una rapida
degradazione enzimatica (Egleton et
al., 1998).
vescicola
Reticolo di
Golgi
vescicola
Reticolo di
Golgi
Stimolo cronico
BRADICHININA
CAPSAICINA
ATP-R
Ca2+
vescicola
Reticolo di
Golgi
MOR
vescicola
Reticolo di
Golgi
α
β
GAMMA
ricevitore
AP2: The AP2 adaptor complex works on
the plasma membrane to internalise
cargo
G protein-coupled receptor
kinase
INTERNALIZZAZIONE
riciclo
degradazione
E il LIGANDE
CHE FINE
FA?
ENDOSOMA
LISOSOMA
LIGANDE
la maggioranza dei peptidi oppioidi subisce una
rapida degradazione enzimatica (Egleton et al.,
1998)..
La maggior parte degli enzimi extracellulari
come il peptide di “degradazione” terminale
sono legati alla membrana attraverso eso-ed
endopeptidasi: l’aminopeptidasi N è uno di
questi enzimi le cui azioni sono cruciali per il
turn-over recettore/ligande
. APN è un prodotto della proteasi
transmembranaria in una vasta gamma di
tessuti e tipi di cellule (endoteliali, epiteliali,
fibroblasti, leucociti), che è in grado di
modulare le risposte di peptidi bioattivi e di
influenzare le funzioni immunitarie.
CHEMIOTERAPICI
.
AMINOPEPTIDASI W o METALLOPROTEINASI DELLA
MATRICE
BESTATIN
LEUCYL-AMINOPEPTIDASI
METALLO PROTEASI DI MEMBRANA
CHEMIOTERAPICI
.
AMINOPEPTIDASI W o METALLOPROTEINASI DELLA
MATRICE
BESTATIN
LEUCYL-AMINOPEPTIDASI
METALLO PROTEASI DI MEMBRANA
.
CO-SOMMINISTRAZIONE DI
DIVERSE PEPTIDASI
Bestatina + amastatin per inibire l’APN
+ Thiorphan, o Phosphoramidon per
inibire la NEP
Captopril per inibire l’enzima angiotensina
Amino_Peptidasi
-
APN
EndoPeptidasi neutra - NEP
neutral endopeptidase (NEP)
L’AMINO PEPTIDASI N è responsabile della
degradazione di diversi peptidi
biologicamente attivi, substrati compresi
Enkerphaline, neurochinina A e beta-EP
quindi, può essere considerato come un
utile marker clinico. Si può prevedere che
l'attività dei peptidi oppioidi a comando
neurale sia potenziato da inibitori delle
peptidasi.
Endopeptidasi neutra (NEP)
L'effetto antinocicettivo (intra tecale)
somministrando
Phosphoramidon + Bestatina IT
RISPOSTA : si valuta la zampa in cui viene iniettata la
capsaicina che induce IL TOPO inizialmente a leccare e
successivamente mordere il sito di iniezione come
massima risposta (autolesionismo),
RISPOSTA che viene significativamente
antagonizzata dal naltrindole,
antagonista selettivo dei DOR.
. Si può prevedere che l'attività
dei peptidi oppioidi a comando
neurale è potenziato dagli
inibitori delle peptidasi.
peptidi oppioidi
Peptidasi
peptidi oppioidi
Peptidasi
inibitori peptidasi
peptidi oppioidi
Peptidasi
inibitori peptidasi
+ Attività peptidi oppioidi -
peptidi oppioidi
Peptidasi
inibitori peptidasi
+ Attività peptidi oppioidi -
peptidi oppioidi
BESTATINA
inibitori peptidasi
+ Attività peptidi oppioidi -
Come un potente inibitore della APN,
la sua azione a livello del sistema
immunitario è stata ricercata, per le
sue funzioni di molecola capace di
“modificare” alcune risposte
immunologiche (Umezawa et al, 1976;. Mathe,
1991), o il recupero immunologico
(immunorecovery, Bruley-Rosset et al, 1979. . Ota e
Ogawa, 1990), l’ematopoiesi (Talmadge et al,
1990), l’antinocicezione (Mathe, 1991
Ozaki et al. (1994) firstly discovered that Bestatin
could increase the ileal twitch inhibitory potency
caused by ME as well as transient inhibition of
twitch contraction after tetanic stimulation.
These results suggested that Bestatin-sensitive
aminopeptidase participated in the post-tetanic
twitch inhibition.
After a further study, the quantitatively different
mechanisms of action in the opioid system between
Bestatin and morphine were elucidated based on
the fact that when challenged with NLX after a long
exposure to the Bestatin and morphine
respectively, the former didn’t induce any NLXinduced contraction which morphine did although
they had similar effects on the post-tetanic
contraction, which suggested the possibility that
Bestatin had a smaller dependence liability (Ozaki,
2002).
La strategia da sviluppare:
insieme all’analgesico fisiologico
“ligande ideale”, privo degli
effetti collaterali (endomorphin),
è l'applicazione degli inibitori e
dei bloccanti le peptidasi
(inibizione del metabolismo delle
peptidasi)
AEA
CBR
AEA
CBR
AEA
CBR
AEA
CBR
FAAH inhibition increases the duration of anandamide’s analgesic effect,
prolonging pain relief at the site of release….
read more: http://www.faqs.org/sec-filings/091116/INFINITYPHARMACEUTICALS-INC_8-K/dex991.htm#ixzz1HWjiSiVv
AEA
CBR
IPI 940
AEA
CBR
IPI 940
INIBITORI “DUALI”
una volta all'interno del cervello si formano
inibitori selettivi
due
- il blocco di entrambi i tipi di
-Enzima zinco metallopeptidase
- dell’enzima enkaphalinase
con conseguente aumento della concentrazione di
enkephaline
i risultati di questi enzimi sono tali da costituire dati
promettenti “farmaci inibitori” per lo sviluppo futuro
di una nuova classe di analgesici che potrebbe
essere di grande interesse nelle sindromi da dolore
grave e persistente.
(Roques e Noble, 1995; Le Guen et al, 2003;. Nobile e Roques, 2007)
Alcuni AA sono fermamente convinti che, un
giorno, una classe completamente nuova
ed efficace di analgesici derivati dalla
Bestatina (neuropeptidi) emergerà come
terapia di prima scelta per diversi stati di
malattie.
A tal proposito alcuni analoghi del peptide
per l’endomorphin-2, che realizza una
analgesia senza effetti collaterali sono stati
sintetizzati con successo (Fichna et al,
2005)..
1
2
3
così si ridurrebbero gli
effetti collaterali
indesiderati associati alla
somministrazione di
oppiacei, come la tolleranza
etc.
I recettori per gli oppioidi sono trasportati intra-assonali verso i
peocessi neuronali, e si ritrovano in periferia nei terminali
sensoriali nervosi periferici.
Studi sulla co-localizzazione hanno confermato la presenza di
recettori sulle fibre C- e A, mentre anche TPRV della variante
V1 a livello di deprimere recettori per gli oppioidi viscerali e su
neuroni esprimenti la isolectina B4, la SP e/o il Calcitonin-generelated peptide coesistente con il fenotipo 12003. I nn simpatici
e le cellule immuinitarie possono anche loro esprimere recettori
per gli oppiacei ma il loro ruolo nel controllo del dolore è poco
chiaro, le affinità dei recettori periferici sono simili.
Peripheral opioid receptors: a new therapeutic concept to target inflammation
Christoph Stein 2003
Tutti 3 tipi di recettori per gli oppioidi mediano
l’inibizione di correnti ad alto voltaggio in
culture di nn afferenti primari.
Questi effetti sono trasdotti da proteine-G (Gi o
Go), in aggiunta gli oppioidi lavorano attraverso
l’inibizione dell’adenil ciclase.
Tutti e 3 I tipi di recettori oppioidei mediano
l’inibizione di correnti calciche ad alto voltaggio
nelle culture di recettori per gli oppiacei a livello
di culture di neuroni afferenti (Mu). Questi
effetti sono trasdotti da proteine da proteine G.
(Gi and/or Go).
Consistent with their effects on ion channels,
opioids attenuate the excitability of peripheral
nociceptor terminals, the propagation of action
potentials, the release of excitatory proinflammatory neuropeptides (substance P,
calcitonin gene related peptide) from peripheral
sensory nerve endings, and vasodilatation
evoked by stimulation of C-fibers. All of these
mechanisms result in analgesia and/or antiinflammatory actions
Peripheral opioid analgesic effects are augmented under
conditions of tissue injury such as inflammation, neuropathy, or
bone damage.
One underlying mechanism is an increased number
(„upregulation“) of peripheral opioid receptors. In
dorsal root ganglia, the synthesis and expression of
opioid receptors can be increased by peripheral tissue
inflammation. Subsequently, the axonal transport of
opioid receptors is greatly enhanced (leading to their
upregulation and to enhanced agonist efficacy at
peripheral nerve terminals. In addition, the specific
milieu (low pH, prostanoid release) of inflamed tissue
can increase opioid agonist efficacy by enhanced Gprotein coupling and by increased neuronal cyclic
adenosine monophosphate level
Peripheral opioid analgesic effects are augmented under
conditions of tissue injury such as inflammation, neuropathy, or
bone damage.
One underlying mechanism is an increased number
(„upregulation“) of peripheral opioid receptors. In
dorsal root ganglia, the synthesis and expression of
opioid receptors can be increased by peripheral tissue
inflammation. Subsequently, the axonal transport of
opioid receptors is greatly enhanced (leading to their
upregulation and to enhanced agonist efficacy at
peripheral nerve terminals. In addition, the specific
milieu (low pH, prostanoid release) of inflamed tissue
can increase opioid agonist efficacy by enhanced Gprotein coupling and by increased neuronal cyclic
adenosine monophosphate level
Of inflammation also leads to an increase in the
number of sensory nerve terminals
(“sprouting”) and disrupts the perineurial
barrier, thus facilitating the access of opioid
agonists to their receptors. Clinical studies
have indicated that the perineural application of
opioid agonists along uninjured nerves (e.g.
axillary plexus) does not reliably produce
analgesic effects, supporting the notion that
inflammation promotes accessibility and/or
efficient coupling of opioid receptors in primary
afferent neurons
The expression of immune-derived opioids is
stimulated by viruses, endotoxins, cytokines,
corticotropin releasing hormone (CRH) and
adrenergic agonists. POMC mRNA, betaendorphin, met-enkephalin and dynorphin are
found in circulating cells and lymph nodes in
conditions of painful inflammation. These
peptides are upregulated in lymphocytes,
monocytes/macrophages and granulocytes within
injured tissue. In patients undergoing knee
surgery, opioid cells accumulate in the inflamed
synovium and attenuate postoperative pain (Stein
et al. 1993). Apparently, these immune-derived
opioids do not induce cross-tolerance to locally
administered morphine (Stein et al. 1996; Likar et
Circulating opioid-containing leukocytes
migrate to injured tissue directed by adhesion
molecules and chemokines. In inflamed tissue,
beta-endorphin-containing leukocytes coexpress L-selectin, and opioid cells, vascular Pselectin, ICAM-1 and PECAM-1 are
simultaneously upregulated. Blocking selectins
or ICAM-1 reduces the number of opioid cells
and intrinsic analgesia.
The release of opioids from immunocytes can
be stimulated by environmental stress,
sympathetic neuron-derived noradrenaline,
interleukin-1beta (IL-1), CRH or chemokines
(Binder et al. 2004; Rittner et al. 2005; 2006).
This release is receptor-specific and calciumdependent, and it is mimicked by elevated
extracellular potassium, consistent with a
regulated secretory pathway, as in neurons and
endocrine cells (Cabot et al. 1997; Mousa et al.
2004; Rittner et al. 2006).
In vivo, the secreted opioid peptides bind to
opioid receptors on sensory neurons and elicit
analgesia within injured tissue (Stein et al.
1993; Schäfer et al. 1994; Schäfer et al. 1996).
The efficacy of this pain inhibition is
proportional to the number of opioid-producing
immunocytes (Rittner et al. 2001). CRH-, IL-1
and stress-induced analgesia can be
extinguished by immunosuppression (Stein et
al. 1990; Schäfer et al. 1994), and by blocking
the extravasation of opioid-containing
leukocytes (Machelska et al. 1998, 2002). In
In patients undergoing knee surgery, opioid
cells accumulate in the inflamed synovium and
attenuate postoperative pain (Stein et al. 1993).
Apparently, these immune-derived opioids do
not induce cross-tolerance to locally
administered morphine (Stein et al. 1996; Likar
et al. 2004). Preclinical Studies
Preclinical Studies on Analgesic and
Antiinflammatory Effects
This basic research has stimulated the
development of novel opioid ligands acting
exclusively in the periphery without central sideeffects. A common approach is the use of
hydrophilic compounds with minimal capability to
cross the blood-brain-barrier. Among the
first compounds were the mu-agonist loperamide
(originally known as an antidiarrheal drug)
and the kappa-agonist asimadoline. Peripheral
restriction was also achieved with newly
developed arylacetamide and peptidic kappaagonists (reviewed in Stein et al. 2003).
While earlier attempts to demonstrate peripheral
opioid analgesia in normal tissue failed, they were
more successful in models of pathological pain
(Stein 1993). In inflammation of
the rat paw, the local injection of low, systemically
inactive doses of mu-, delta- and kappa
agonists produced analgesia that was dosedependent, stereospecific and reversible by
selective antagonists. Some agonists produced
both peripheral analgesic and antiinflammatory
effects. Possible underlying mechanisms of the
latter include a reduced release of
proinflammatory neuropeptides or cytokines, and a
diminished expression of adhesion molecules.
Potent antinociception was also shown in models of
nerve damage and of visceral, thermal and
bone pain (reviewed in Stein et al. 2003).
Clinical Studies on Analgesic and Antiinflammatory
Effects
Controlled studies have demonstrated significant
analgesic effects following the local
application of opioids at sites of injury. The
intraarticular administration of the mu-agonist
morphine is the best examined clinical application.
After knee surgery, it dose-dependently
reduces pain scores and/or supplemental analgesic
consumption by a peripheral mechanism of
action and without side-effects (reviewed in Kalso
et al. 2002; Stein et al. 2003). Intraarticular
morphine is active in the presence of opioid
containing inflammatory cells (Stein et al. 1996;
Likar et al. 2004) and in chronic rheumatoid and
osteoarthritis (Stein et al. 1999). Its effect is
similar to a standard intraarticular local anesthetic
or steroid injection and is long lasting (up to 7
days), possibly due to morphine’s anti-inflammatory
activity.
Other trials showed efficacy of
local opioid injections in bone pain, dental pain,
corneal abrasions and visceral pain. Several
studies found no peripheral effects of opioids. The
majority of those trials examined the injection
of agonists into the noninflamed environment along
nerve trunks. This suggests that intraaxonal
opioid receptors may be „in transit“, and not
available as functional receptors at the membrane.
Novel peripherally restricted opioids have recently
entered human trials, including a kappaagonist
that markedly reduced visceral pain in patients with
chronic pancreatitis without severe
side effects.
. Beyond the absence of central side-effects, such
novel compounds may offer
advantages such as anti-inflammatory effects, lack
of tolerance, lack of constipation, lack of
gastrointestinal, hepatic, renal and thromboembolic
complications (typically associated with
nonsteroidal anti-inflammatory drugs), and efficacy
in neuropathic pain (Stein et al. 2003).
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