Goro Katsuura

Caerulein and cholecystokinin suppress β-endorphin-induced analgesia in the rat

Abstract The analgesic action of β-endorphin, as observed in the hot plate test with rats, was effectively suppressed by intracerebroventricular (i.c.v.) injection of caerulein and cholecystokinin octapeptide (CCK-8). The effect of caerulein was particularly striking; this peptide in doses of more than 0.09 nM lessened or abolished the analgesic effect of β-endorphin in a dose of 0.7 nM. On the other hand, non sulfated CCK-8 had no significant effect on β-endorphin-induced analgesia.

Adrenocortical stimulation by a cholecystokinin preparation in the rat.

Abstract The effect of a cholecystokinin (CCK) preparation on the secretion of corticosterone when injected intraperitoneally and intraventricularly was studied in the rat. Both routes of injections produced pronounced elevation of plasma corticosterone levels, but the minimum effective dose by intraventricular injection was 10 mU/rat and that by intraperitoneal injection 2 U/100 g, or approximately 5 U/rat. Although the effect was observed in vagotomized rats, CCK did not affect the pituitary gland itself. It was inferred that CCK acts directly or indirectly on CRF neurones in the brain. Since CCK preparation used in the present experiments was contaminated with motilin, the effect of synthetic motilin on the adrenocortical secretion was also examined. However, no stimulatory effect was found following intraventricular injection of this peptide.

Cholecystokinin tetrapeptide, proglumide and open-field behavior in rats

The effect of cholecystokinin tetrapeptide (CCK-4) was studied in an open field situation. CCK-4 increased locomotion and rearing and the effect was enhanced by proglumide, a selective antagonist of CCK-8. This is in sharp contrast to our earlier findings that CCK-8 decreased the open-field behavior and that proglumide completely blocked the effect. Thus, the effects of CCK-4 and CCK-8 appear to be opposite to each other in that one is excitatory and the other inhibitory to open-field responses.

Suppressive action of cholecystokinin octapeptide on the behavioral effects of L-DOPA in the rat

Intracerebroventricular (i.c.v.) administration of cholecystokinin octapeptide (CCK-8) appeared to suppress the effects of L-DOPA and antagonize the actions of thyrotropin-releasing hormone (TRH). This was not only proved by the behavioral rating, but also by locomotor activity counting. thus, the sedative action of CCK-8 and the antagonizing effect of this peptide on the central actions of TRH were clearly demonstrated.

Blocking of cholecystokinin octapeptide behavioral effects by proglumide

An open field apparatus was used to assess the effect of proglumide, a selective antagonist of cholecystokinin octapeptide (CCK-8), to block the behavioral effect of CCK-8 in rats. Intracerebroventricular (ICV) injection of CCK-8 (0.5 to 2 micrograms) was effective in suppressing general exploratory activities and this effect was blocked by proglumide at doses of 2 to 5 micrograms administered ICV or 1 mg/kg administered subcutaneously. The effect of peripherally administered CCK-8 (10 micrograms/kg) was blocked by peripherally administered proglumide at a dose of 2 mg/kg but not by centrally administered proglumide at a dose of 5 micrograms/rat. The behavioral effect of CCK-8 was thus clearly blocked by proglumide.

Suppressive effect of cholecystokinin and its related peptides on β-endorphin-induced catalepsy in rats

The effects of the C-terminal octapeptide of cholecystokinin (CCK-8) and its related peptides on the onset and duration of beta-endorphin-induced catalepsy on injection of the peptides into the lateral ventricle were investigated in male rats. The onset of catalepsy was delayed to some extent by nonsulfated CCK-8 and CCK-7 but CCK-8 and caerulein were ineffective. Naltrexone and caerulein significantly shortened the duration of catalepsy, but CCKs were less effective to shorten it. Pentagastrin had no effect on either parameter.

Effect of caerulein on plasma corticosterone concentration in the rat

Abstract Intraperitoneal injection of caerulein produced a pronounced increase in plasma corticosterone levels in intact rats. Since this effect was not observed in hypophysectomized rats, it is assumed that the peptide does not affect the adrenal gland directly. Intracerebroventricular injection of caerulein was also ineffective in stimulating corticosterone secretion, and in vitro experiments for ACTH release indicated that caerulein could not affect pituitary tissue itself. The fact that the effect of caerulein disappeared after subdiaphragmatical vagotomy suggests that the action site is at a peripheral level, but not in the central nervous system.