Effect of antibodies that disrupt synaptotagmin-syntaxin interaction on neurotransmission in the squid giant synapse

S77

THE RELATION BETWEEN THE NO-GENERATIVE NEURONS AND THE CENTRAL CIRCUITRY FOR RHYTHMIC FEEDING IN THE POND SNAIL, .Lymnaeaslugnalis.

055

HISAYO SADAMOTO’.

DA1 HATAKEYAMA’,

SATOSHI KOJIMA’,

YUTAKA FUJITO*, ETSURO

ITO’

‘Lab. of Animal Behavior and Intelligence, Div. of Biological Sciences, Graduate School of Science, Hokkaido Sapporo 060-0810, *Dept. of Physiology, School of Medicine, Sapporo Medical Univ., Sapporo 060-8556

IJniv.,

To examine whether nitric oxide (NO)-generative neurons are involved in central circuitry for feeding in the pond snail, Lymnuea stugnalis, two staining techniques for NADPH diaphorase and serotonin (5-HT) were applied for its CNS. The former technique is known to show the localization of NO synthase; the latter is employed to indicate the feeding circuitry because 5-HT is a main transmitter in this circuitry. One motoneuron was found to be a putative NO-generative neuron. This motoneuron is not involved directly in the coordination of feeding pattern but is activated simultaneously Taking account of the diffusion effects of NO, with the feeding to control oesophageal and gut tissues for the digestion. the NO released from B2 motoneuron, when the feeding is started, is thought to sufficiently modulate the activity of The sensory nerves included both putative NO-generative fibers and serotonergic fibers. neurons in the feeding circuitry. Although these fibers are not identical in each of nerves, NO may influence upon the initiation of the feeding. Therefore, our present findings clearly showed that NO is not involved in transmission within central circuitry for the feeding, but suggested that NO can crucially affect the feeding behavior, such as initiation and modulation of the feeding pattern.

ACTIVATION OF PROTEIN KINASE C POTENTIATES TRANSMITTER RELEASE FROM

056

GOLDFISH RETINAL BIPOLAR CELLS

NAOTOSHI

MINAMI,

KEN BERGLUND,

Department

of Psychology,

Bunkyo-ku,

Tokyo 113-0033

TAKESHI

Graduate School of Humanities

We examined whether transmitter

(glutamate)

by using the response

not by an ineffective phorbol ester, 4cr-phorbol 12,13-didecanoate of horizontal

bisindolylmaleimide

cells.

potentiated the slow component modifies

The PMA-induced

I (500 nM).

the slow component

Transmitter

FUKUDA’,

1Z-myristate

of a catfish retinal horizontal

13-acetate (PMA, 100 nM), but

These agents did not affect the glutamate-induced

of transmitter

release of bipolar cells consists

which may reflect the recruitment

NEUROTRANSMISSION

MITSUNORI

(100 nM).

potentiation

Ca” current, and the released

of NMDA receptors

phorbol

without affecting the Ca2+-dependence

EFFECT OF ANTIBODIES

057

of protein kinase C (PKC) in goldfish retinal

voltage clamped to measure the presynaptic

was detected simultaneously

cell as a reporter. Transmitter release was potentiated by a PKC activator,

responses

The University of Tokyo, 7-3- 1 Hongo,

and Sociology,

release could be modified by the activation

bipolar cells. An isolated bipolar cell was whole-cell transmitter

SAKABA and MASAO TACHIBANA

release was blocked

by a PKC inhibitor,

of the fast and slow components.

of exocytosis.

We suggest that the activation

PMA of PKC

process of synaptic vesicles in goldfish retinal bipolar cells,

THAT DISRUPT SYNAPTOTAGMIN-SYNTAXIN

INTERACTION

ON

IN THE SQUID GIANT SYNAPSE

MUTSUYUKI

SUGIMORI?.

RODOLFO

LLINz&,

KATSUHIKO

MIKOSHIBA’,i

‘Dev. Neurobiol. Lab., BSI, RIKEN, Saitama 351-0198, *Dept. of Physiol. and Neurosci., New York Univ. Med. Ctr., NY 10016, USA, 3Dept. of Mol. Neurobiol., Inst. of Med. Sci., Univ. of Tokyo, Tokyo 108-8639 Synaptotagmin

I is an integral membrane

protein of secretory

vesicles,

two C2 domains (named C2A and C2B domains) in the cytoplasmic C2 domains.

Since the C2A domain of synaptotagmin

vitro, it has been proposed attempt at elucidating

that this Ca *+-dependent

whether this interaction

against the squid synaptotagmin interaction

neurotransmission

(especially

injection

vesicles (Sugimori

is important

of anti-Syt-C3A

functions

for transmitter

antibody

et al. (1998) Neuroscience

synaptotagmin-syntaxin 85, in press).

interaction

It has

manner (above 200 PM Ca?+) irz

release irz I?~v. we produced

or syntaxin (anti-Syx), or anti-Syx

cells.

secretion via the\e

as a Caz+ sensor for transmitter

vesicular fusion step) without affecting presynaptic

This result suggests that the Ca?+- dependent

in neural and some endocrine

I binds syntaxin in a Calf- dependent interaction

C2A domain (anti-Syt-C3A)

in vitro. Presynaptic

abundant

domain, and is involved in transmitter

release.

specific

In an

antibodies

which inhibited synaptotagmin-syntaxin into the t,quid giant presynapse

blocked

action potential or the inward Ca?+ current. might be involved

in the fusion of synaptic