Spect findings in schizophrenia and their relations to dopamine hypothesis

III

STRESS-INDUCED EMOTIONAL CHANGES AND THE BRAIN NORADRENALINE SYSTEM IN THE RAT MASATOSHI TANAKA, MASAI41 YOSHIDA, AKIRA TSUDA AND HIDEYASU YOKOO, Department of Pharmacology, Kurume University School of Medicine, Kurume 830, Japan. By measuring levels of noradrenaline (NA) and its major metabolite, 3-methoxy4-hydroxyphenylethyleneglycol sulfate (MHPG-S04) in the rat brain regions, we have reported that immobilization stress caused the marked increases in NA release in the extended brain regions, whereas psychological stress, wherein psychological other than physical factors were more predominantly involved, caused increases in NA release preferentially in the hypothalamus, amygdala and locus coeruleus (LC) region. These increases in NA release induced by both stresses were attenuated by diazepam, a typical anxiolytic of benzodiazepines, in a dose-dependent and Ro 15-17 Diazepam also attenuated 88(an antagonist of benzodiazepines)-reversible manner. the emotional responses of the rats exposed to immobilization stress. Yohimbine, an a2-antagonist, which elicites anxiety in humans and increases NA release in these regions, enhanced anxiety-related behaviors in the two behavioral tests. Ethyl-$-carboline-3-carboxylate possessing anxiogenic property in humans increased These findings were supported by the NA release in these rat brain regions. In conclusion, we suggest that increases in NA studies using microdialysis. release in such brain regions as the hypothalamus, amygdala and LC are closely related to the provocation of anxiety and/or fear of the animals exposed to stress.

SELECTIVE INVOLVEMENTS

OF ENDOGENOUS

TO STRESS KINJI YAGI --- AND Japan.

ONAKA, ---

TATSUSHI

OPIOIDS

OR MONOAMINES

IN VASOPRESSIN

Departmentof Physiology, JichiMedicalSchool,

RESPONSES

Tochigi-ken

329-04,

Vasopressin secretion by the pituitary is potentiated after physical stress but suppressed after fearrelated emotional stress in rats. We have investigated whether receptor antagonists for opioids, dopamine A non-selective or histamine alter the vasopressin response to physical or fear-related emotional stress. opioid receptor antagonist, naloxone augmented the vasopressin response to physical stress but did not change the vasopressin response to emotional stress. A dopamine Dl receptorantagonist, SCH23390

markedlyreducedthe responseto physical stressbut did not affectthe responseto emotionalstress.A dopamine D2 receptorantagonist, sulpiride did not alterthe vasopressin responseto physical or emotional stresswhereas it augmented the facilitatory vasopressinresponse to SC injectedhypertonicsaline. Althougha histamineHI receptorantagonist, pyrilamine did not influence the responseto emotionalstress, a H2 receptorantagonist, ranitidine blockedthe responseto occur. These results demonstrate that the involvements of some of the neuroactive substance receptors that. were tested physical or emotional stress, and therefore support the view that the distinctive involved in the vasopressin response to each of the physical and emotional stress.

were selective to either neural mechanisms are

C. Neurobiology of Mental Diseases SPECT FINDINGS

IN SCHIZOPHRENIA

AND THEIR

RELATIONS

TO WPAMINE

HYPOTHESIS.

Cy, 2630

Sugitani,TOY-

930-01, Japan.

The relationshipsbetweenclinical symptans,eye movements,and regionalcerebralblood flow (rU3F)were examinedin 17 medicated

patients

with

schizophrenia.

rCBF was measured using

The

N-isopropyl-p-(I-123)lodoanphetanine (IMP) SPECT, and the scanningeye m3venentsduringBenton's visual retentiontest were recordedwith Nat eye mark fixations

in the

and with

decreased

to study

the

tion

with

an

showed

a significant

rCBF in the

relationship

in the medial

autoradiograph. lel

patients

prefrontal

increase

cortex rats

in DA, cingulate

superior

correlation frontal

rCBF and dopanine

between

Lesioned

rCBF in the anterior

left

(n=lO) DOPAC cortex

on rCBF showed

in the an

with

and basal

(DA)

metabolism,

rat

increased

duration

negative

area

and HVA concentrations. where

The mean

recorder.

brain

was

symptans

ganglia the

There

effect

was,

one hand,

other.

Next,

of DA depriva-

investigated

using nuclei

however,

strikingly

on the

on the

rCBF in the accunbens

the DA metabolismwas

of eye

an

reduced.

(I-125)

IMP

in paralincreased