Signal transduction WS 09/10

Olfaction

Signal transduction

Emotions and behaviour

memory

orientation in environment

quality ofnutrients / food

social behaviour

choosing a partner

Signal transduction

Axel, R. (1995) Spektrum der Wissenschaft, Dezember 1995

Olfaction

OlfactionSignal transduction

Signal transduction

Olfactory thesholds

Signal transduction

Decline in olfactory sensitivity

Signal transduction

Quelle: Kleene + Gesteland (1981) Brain Res. 229: 536

olfactory neuron

supportingcell

olfactoryepitheliumbasal

cell

Anholt, R.R (1987) Trends in Biochemical Science 12, 58ff

The olfactory epithelium

Signaltransduktion

olfactory neuron

supportingcell

Anholt, R.R (1987) Trends in Biochemical Science 12, 58ff

mammals5 - 120 million

olfactory neurons

humansapprox. 10 million

life timeapprox. 4 – 8 weeks

basalcell

Signal transduction

c = ciliafunction: detect odorants; chemo-electrical signal transduction

s = somafunction: energy production,protein biosynthesis

a = axonfunction: generate and conductaction potentials

d = dendrite

Signal transduction

Odorants excite olfactory neurons

depolarisation

odorant

Signal transduction

depolarisation hyperpolarisation

Duftstoff

Signal transduction

Signal transduction

in olfaction

Signal transduction

receptorsspecificty

sensitivityenzyme cascade

electrical responseion channel(s)

Olfaction

Signal transduction

odorantreceptor

Olfaction

Signal transduction

G-protein: Golf

Olfaction

Signal transduction

Adenylyl cyclase

Olfaction

Signal transduction

CNG channel

Olfaction

Signal transduction

amplification

Cl- channel

Olfaction

Is the signalling cascade

supported by

chloride efflux?

Signal transduction

OlfactionSignal transduction

Ion distribution (vertebrate)

outside inside

Na+ 140 mM 3-30 mMK+ 5 mM 140 mMCa2+ 2 mM < 1 µMMg2+ 2 mM einige mM Cl- 140 mM 10 mM

OlfactionSignal transduction

high [Cl-] in the neuron

⇒ amplification

Signal transduction

Properties of the

molecular components

of the signalling cascade