1-Norepinephrine (NE), Epinephrine (E) and Histamine have not been detected in C. elegans (
Duerr J.S. et al., 1999)
2- Tyramine (ser-2) and dopamine (dop-1, dop-2) receptors are found in C. elegans (Tsalik E. et al., 2003)
cha-1 choline acetyl transferase (ChAT)

(C. elegans book II CSHL Press, 1997.Rand J.B. and Nonet M.L. Appendix II: Neurotransmitter assignments for specific neurons)

Altun-Gultekin Z. F. et al. 2001

Rand J.B. et al 1998


2ALN's, 11AS's ,4CA's, 9DA's, 7DB's, 2HSN's(weak and variable staining), M1, 2M2's, M4( variable staining), M5, MC (weak or nonexistent staining), 2PLN's, 4SAA's, 3SAB's, 2SDQ's, 4SIA's, 4SIB's,
4SMB's, 4SMD's, 12VA's, 11VB's, 6VC's, 2AIY's, 2AIA's.

Note: there are approximately 100 cholinergic neurons in C. elegans, most of which are excitatory motor neurons.

Ab staining

unc-17 and cha-1 are in an operon and expressed in the same cells.


unc-17 vesicular acetylcholine transporter (VAChT)

see cha-1

see cha-1 note HSNs and VC4 and VC5 express both VAChT and VMAT (Duerr J. S. et al. 2001)
unc-25 glutamic acid decarboxylase (GAD)

Eastman C.L. et al. 1999


19 D neurons of ventral cord (DD and VD classes), 4RME's, AVL, RIS, DVB

unc-25::GFP reporter

unc-47 vesicular GABA transporter (VGAT) expression similar to unc-25 see unc-25
eat-4 vesicular glutamate transporter (VGluT)

Lee R.Y.N. et al. 1999


15 different anatomical types (ADA, ALM, ASH, ASK, AUA, and AVJ or AIN, AVM, FLP, IL1, LUA, OLL, OLQ, PLM, PVD, and PVR; 34 cells total) of extrapharyngeal neurons. In the pharynx: M3, NSM, possibly I5.

eat-4::GFP reporter also eat-4::LacZ reporter

cat-1 vesicular monoamine transporter: VMaT

Duerr J.S. et al. 1999


all Dopamine and 5-HT cells + others: ADE, PDE, CEP, NSM, HSN,VC4,VC5, ADF, RIH, AIM, RIC, CAN, an additional pair in lat ganglia (weak staining)+ some male-specific cells in VC and the tail.

Ab staining

VMaT transports monoamines into synaptic vesicles from cytosol; hence, has serotonin, DA, NE, tyramine, octopamine, histamine transport activity (exists in DA, 5-HT, octopamine, histamine, NE and E neurons)

note: HSNs and VC4 and VC5 express both VAChT and VMaT (Duerr J. S. et al 2001).

cat-2 tyrosine hydroxylase: TH

Lints R. and Emmons S.W. 1999


two ADE, two PDE, and four CEP neurons, three pairs of ray neurons (R5A, R7A, R9A) in the male tail, 4 socket cells of the male spicules

cat-2::GFP reporter

Dopamine biosynthesis rate limiting enzyme. Catalyzes the initial step in DA synthesis.
- formaldehyde-induced fluorescence (FIF) Sulston J. et al. 1975
see cat-2 dopamine expression
dat-1 dopamine membrane transporter

Jayanthi L.D. et al, 1998

Nass R. et al, 2001

Dopaminergic neurons: two ADE, two PDE, and four CEP neurons. Transport of dopamine into synaptic vesicles.
tph-1 tryptophan hydroxylase

Sze J.Y. et al. 2000


2NSM's, 2ADF's, 2HSN's(hermaphrodite-specific), 6CP's (male-specific),2 AIM's (rarely), RIH (rarely)

tph-1::GFP reporter

(see below for complete serotonergic neurons list)

Note:cod-5 is not tph-1 and cod-5 animals are not serotonin-deficient (C. Loer-pers. comm).

Note: Both tph-1 and bas-1 (AAAD) knockouts have residual serotonin-immunoreactivity that either represents serotonin coming from an unexpected source, or some serotonin relative molecule that may accumulate to sufficient levels in the mutants to be seen with the antibody. cat-4(e1141) has also been reported as having residual serotonin-immunoreactivity (C. Loer-pers. comm).

Note: phenylalanine hydroxylase bas-2, is not expressed in neurons.

- 5-HT

Loer and Kenyon, 1993

C. elegans book II CSHL Press, 1997.Rand J.B. and Nonet M.L. Appendix II: Neurotransmitter assignments for specific neurons

Sze J.Y. et al. 2000

Sawin E.R. et al. 2000

Lints R. et al., 2004



2 NSM's, RIH, 2 ADF's, 2 AIM's, CP1-6 (male), 2 R1B's (male), 2 R3B's (male), 2 R9B's (male), CA1-4 (male), 2 HSN's (herm), VC4 (herm), VC5 (herm),2 PHB's, I5, RPAG (=unpaired, Right Preanal Ganglion Neuron; PDC or PGA?; male-specific)

Note:CA1-4; weak and unreliable staining.
VC4,VC5: weak and unreliable staining

histochemistry and immunostaining (anti-serotonin)

5-HT functions in the worm:

- pharyngeal pumping (increases)

- egg-laying (increases)

- foraging behavior

- male-mating

- locomotion (inhibits)



bas-1 putative Dopa decarboxylase=L-aromatic amino acid decarboxylase (DDC=AAADC) Loer C.M. et al. 1998 West Coast Worm Meeting abstract 161 expression pattern not published In serotonin biosynthesis; tryptophane is first hdroxylated by a tryptophane hydroxylase and then decarboxylated by an AAADC to yield serotonin.
cat-4 putative GTP cyclohydrolase I (GCH) Loer al. 1998 West Coast Worm Meeting abstract 161 expression pattern not published GCH catalyzes the first step in biopterin cofactor synthesis. All AAAH enzymes (tryptophane hydroxylase in 5-HT synthesis; tyrosine hydroxylase in dopamine synthesis; phenylalanine hydroxylase in tyrosine synthesis/phenylalanine metabolism) require a biopterin cofactor to catalyze their respective hydroxylations.