laboratory of chronobiology, department of science and technology, national university of quilmes,...
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Laboratory of Chronobiology, Department of Science and Laboratory of Chronobiology, Department of Science and Technology, National University of Quilmes, Buenos Aires, Technology, National University of Quilmes, Buenos Aires,
Argentina.Argentina.
Algo de ritmos circadianos, de avances de fase inducidos por luz y de resincronización
Una intro a lo que hacemos con el SCN, con el cGMP, el NO, PKG y la PDE, sin hablar de MAP, ni CRE, CREB, TNF,y menos de tve, BBC, CNN, FOX,
BBVA, y bla bla bla.
Los ritmos ocurren en todos los niveles de organización
INTRODUCCIINTRODUCCIONON
QUIMICO
Expresión génica, actividad eléctrica, síntesis y liberación de neurotransmisores.
CELULAR
FISIOLÓGICO Temperatura, presión arterial, frecuencia cardíaca, niveles de hormonas en sangre.
CONDUCTUAL
Conducta alimentaria, ciclo sueño/vigilia, actividad locomotora.
CELULAR FISIOLOGICO
POBLACIONALCONDUCTUAL
Propiedades Generales de los ritmos
• AMPLITUD
• FASE
• PERIODO
PARAMETEROS PERIOD PHASE SHIFT
La Cronobioloia Estudia los Ritmos Bilogicos
AMPLITUDE
TIME
Espectro de los Ritmos Biológicos
Rhythm Period Example0,1 sec electroencephalogram1 sec electrocardiogram6 sec breathing rhythm
60 min pulsatile hormone secretion90 min sleep staging
sleep - wake cyclebody temperature
28 days menstrual cycle365 days hibernation
Ultradian
Circadian
Infradian
24 hours
En mamíferos, el reloj biológico se halla en los núcleos supraquiasmaticos (SCN)
Output rhythms
Behavior
light
Suprachiasmatic Nucleus (SCN)
CARACTERISTICASNEUROQUIMICAS
EXPRESION GENES RELOJ
VIP PEPTIDO VASOACTIVO INTESTINAL
AVP VASOPRESINA
Región dorsomedialEXPRESION RITMICA
Región ventrolateralEXPRESION INDUCIDA POR LUZ
NSQ
QO
Los núcleos supraquiasmáticos (NSQ) son la sede del reloj biológico en mamíferos
3V: TERCER VENTRICULO
QO: QUIASMA OPTICO
INTRODUCCIINTRODUCCIONON
Calb: Calbindina
Ciclo LUZ-OSCURIDAD
INPUT
OSCILADOR
TEMPERATURA
NIVELES HORMONALES
EXPRESION DE PROTEINAS
ACTIVIDADLOCOMOTORAETC.
OUTPUT
Principales componentes del Sistema Circadiano
ZEITGEBER(exógeno)
oscilador (endógeno)
Sincronización Acoplamiento
Mecanismo de oscilación: el reloj molecular
CITOPLASMA
NUCLEO
CKI
CRYPER
PER
Degradación víaproteosoma
Per
Cry
Rev
otros
Genes blancoE-box
CLO
CK
BM
AL
CRYPER
CRY
PER
INTRODUCCIINTRODUCCIONON
L:D (14:10) vs D:D
Subjective DaySubjective Night
Hours 240
Light pulse
Phase advance
Light pulse
Phase delay
Subjective NightSubjective Day
Subjective DaySubjective Night
Hours 240
Light pulse
Phase advance
Light pulse
Phase delay
Subjective NightSubjective Day
Phase response curve (PRC) (PRC)
Ca2+
CaMKII
Ca2+-Calmodulin
Glu
Ca2+
NMDA-R
Light
CaMKII has been implicated in the resetting of the circadian clock by light exposure (Golombek and Ralph, 1994)
Signal transduction pathways responsible of photic mammalian phase advances
Ca2+
CaMKII
Ca2+-Calmodulin
NOS
Glu
Ca2+
NMDA-R
Light
A role for nNOS in circadian responses to light has been indicated by several pharmacological and electrophysiological studies (Melo et al., 1997)
Ca2+
CaMKII
Ca2+-Calmodulin
NOS
NOS
Glu
Ca2+
NMDA-R
Light
There is a direct pathway between CaMKII and NOS in the SCN (Agostino et al, 2004, Neurochem Int 44: 617-625)
CaMKII
Ca2+-Calmodulin
Ca2+
NOS
PKG
GC
Glu
Ca2+
NMDA-R
Light
An involvement for the NOS-GC-PKG pathway in light-induced phase advances has been indicated by several studies.
- cGMP induces phase advances in vitro (Prosser y Gillette, 1996)
- PKG inhibition blocks light-induced phase advances in vivo (Mathur et al., 1996)
NO
cGMP
Late night(phase advance)
Daily and circadian variations of cGMP
content in the hamster SCN
A
fmol
es c
GM
P /
g
prot
ein
0.05
0.10
0.15
0.20
0.25
0.30
0.35 (n=11)(n=10)
(n=17)
(n=9)
(n=10)
(n=13)
(n=11)(n=10)
(n=17)
(n=9)
(n=10)
(n=13)
** **
4 8 12 16 20 24 4 8 12 16 20 24
*
#
*
#
LD
B
CT
fmole
s cG
MP
/
g p
rote
in
0.05
0.10
0.15
0.20
0.25
0.30
0.35
(n=5)
(n=6) (n=6)
(n=5)(n=5)
(n=5)(n=5)
(n=4)
(n=5)
(n=4)
(n=6) (n=6)**
4 8 12 16 20 244 8 12 16 20 24
# #
** **
DD
Maximal values were found during the day
B
CT
fmol
es P
i /
g pr
otei
n x
5 m
in
200
400
600
800
1000
1200
1400
(n=4)
(n=5)
(n=5)
(n=5)
(n=5)
(n=4)(n=4) (n=4)
(n=5)
(n=5) (n=5)
(n=5)
4 8 12 16 20 24
#
* *
** **#
4 8 12 16 20 24
ZT
A
fmol
es P
i /
g pr
otei
n x
5 m
in
200
400
600
800
1000
1200
1400
(n=16)(n=21)
(n=20) (n=20)
(n=16)
(n=20)
(n=11)
(n=21)
(n=20)
(n=9)(n=9)
(n=11)
* *
# #
4 8 12 16 20 24 4 8 12 16 20 24
Daily and circadian variations of cGK
activity in the hamster SCN
LD
DD
Maximal values were found during the day
CTRL Pulse CTRL Pulse
pm
ole
s cG
MP
/
g p
rote
in
0.00
0.02
0.04
0.06
0.08
0.10
0.12
0.14
0.16
0.18
CT14 CT 18
*
A cGMP levels in the SCN
CTRL Pulse CTRL Pulse
fmol
esP
i/ g
pro
tein
x 5
min
0
50
100
150
200
250
300
CT14 CT 18
*
cGK activity in the SCNB
A: a 5-min light pulse increases cGMP levels at CT 18 but not at CT 14 (modified from Ferreyra and Golombek, 2001).
B: PKG activity significantly increased after a 5-min light pulse at CT 18 but was unaffected by the same photic stimulus at CT 14 (Golombek et al, 2004)
The GC-PKG pathway is involved light-induced phase advances
Phase advances of the circadian rhythm of locomotor activity are blocked by the NOS inhibitor L-NAME, the GC inhibitor ODQ and the cGK inhibitor KT-5823. On the other hand, the NO donor SNAP significantly increases light induced phase advances (Golombek et al, 2004).
0
20
40
60
80
100
120
140
160
Ph
ase
shif
t (m
inu
tes)
Vehicle
+ lightKT-5823
+ light
ODQ
+ lightL-NAME
+ light
Vehicle
+ light
SNAP
+ light
* **
*
dim light
CaMKII
Ca2+-Calmodulin
Ca2+
NOS
Glu
Ca2+
NMDA-R
Light
NO
PKG
GC
NOcGMP
Phase advance
?Phase delay
?
Late Night
Early Night