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Biomedical subjects

S Sakurada

Publications and source records attributed to S Sakurada.

197 records · Page 11Linked to original sources
PubMed1975

[Effects of beta-phenylethylamine derivatives on the central nervous system. (5) Changes in the volume of spontaneous movement in mice with intracerebral administration of tyramine].

Influence of tyramine (Ty) on behavioural changes in mice was studied and the following results obtained: 1) 30 min after Ty (160 mug, i.c.), brain noradrenaline and serotonin levels decreased while dopamine levels increased. 2) When Ty was injected i.c. into isocarboxazide (Iso) pretreated mice, spontaneous motor activity (SMA) measured by photo-cell counters method increased markedly but SMA by wheel cage method decreased. 3) When Ty was injected i.c. into Iso and p-chlorophenylalanine (p-CPA) (400 mg/kg, i.p., daily X 2) pretended mice, SMA measured by photo-cell counters method increased. While, SMA increased from 30 to 90 min after Ty, SMA measured by wheel cage method decreased till 30 min after Ty. 4) When Ty was injected i.c. into Iso and alpha-methyl-p-tyrosine (alpha-MPT) (125 mg/kg, i.p., daily X 2), SMA measured by photo-cell counters method decreased markedly when compared with Iso+saline treated group. When SMA was measured by wheel cage method, a difference between alpha-MPT+Iso-Ty treated group and Iso-saline group was not obtained. 5) When Ty was injected i.c. into p-CPA+alpha-MPT+Iso pretreated mice, SMA measured by photo-cell counters method did not show any increase compared with control group. 6) SMA produced by Iso-Ty in mice pretreated with haloperidol was significantly inhibited. A 50% dose of inhibition was seen with 0.3 mg/kg. From our results, it appears that an increase of SMA induced by Iso+Ty as revealed by the photo-cell counters method may be related to brain catecholamines and serotonin while a decrease of SMA in wheel cage method may be related to brain serotonin.

Animals↗
PubMed1975

[Effects of beta-phenylethylamine derivatives on the central nervous system. (5) The effect of intracerebral administration of tyramine on head twitching in mice pre-treated with isocarboxazid].

Effects of drugs on head-twitches induced by tyramine (Ty) in isocarboxazide (Iso) pretreated mice were studied and the following results obtained: 1) In beta-phenylethylamine derivatives, p-hydroxyamphetamine in non-treated and Iso-pretreated mice and Ty in Iso-pretreated mice produced head-twitches. 2) Injection of 5-HTP (i.c. and i.p.) into mice induced head-twitches. 3) Although head-twitches were not induced by a low dose of 5-HTP (20 mg/kg, i.p.), in Iso pretreated mice, the number of headtwitches increased markedly in the Iso-Ty treated group when Ty was injected i.c. in Iso+5-HTP (20 mg/kg) pretreated mice. 4) When Iso-Ty was injected into alpha-methyl-p-tyrosine pretreated mice, the number of head-twitches increased markedly compared with Iso-Ty treated group. 5) When Iso-Ty was injected into mice sustained with p-chlorophenylalanine, the number of head-twitches decreased markedly compared with the Iso-Ty treated group. 6) The number of head-twitches decreased markedly when Iso-Ty was injected into dimetotiazine pretreated mice, however the administration of Iso-Ty in haloperidol pretreated mice had no influence on head-twitches. 7) It is concluded that serotonin is the acting mediator in the head-twitch response.

5-Hydroxytryptophan↗
PubMedDate not supplied

A new class opioid peptide, [D-Arg2, beta-Ala4]-dermorphin tetrapeptide; physical dependence liability in mice.

Development of morphine-like physical dependence of the [D-Arg2, beta-Ala4]-dermorphin tetrapeptide (H-Tyr-D-Arg-Phe-beta-Ala-OH) has been evaluated and compared with the physical dependence liability of morphine or pentazocine. Degree of the physical dependence was assessed by the naloxone-precipitated jumping behaviour in mice after treatment of a single dose of each compound. The number of jumps and the time of latency to first jump were recorded in this experiment. Number of jumps in a group pretreated with the peptide showed less than that in morphine-treated group. In addition, latency to the appearance of the first jump in the peptide-treated mice was later than that in the morphine-treated group. The present results indicate that the physical dependence induced by [D-Arg2, beta-Ala4]-dermorphin tetrapeptide may be less marked than that produced by morphine. It is also interesting to note that the antinociceptive effect of this opioid peptide is more powerful and of longer duration than that induced by morphine or pentazocine.

Analgesics, Opioid↗
PubMedDate not supplied

Actions of intracerebroventricular administration of kyotorphin and an analog on thermoregulation in the mouse.

Intracerebroventricular (ICV) administration of kyotorphin (L-Tyr-L-Arg) and cyclo (N-methyl-L-Tyr-L-Arg), its analog, produced significant dose-dependent hypothermic responses in mice at an ambient temperature of 24 degrees C. The hypothermic action of kyotorphin was much greater than that of Met-enkephalin (Met-ENK) but less than that of cyclo NMTA. This action was slightly but not significantly reversed by intraperitoneally administered naloxone (8 mg/kg), an opioid receptor antagonist. Met-ENK utilized as a control peptide in this study also produced a dose-dependent hypothermia which was slightly antagonized by naloxone (8 mg/kg, IP). Thyrotropin releasing hormone (TRH) injected ICV produced hyperthermia dose-dependently. The hypothermia induced by kyotorphin, its cyclic analog and Met-ENK was prevented by a small dose of TRH (0.18 microgram = 0.5 nmol/animal) which by itself had little effect on body temperature. A TRH neuronal system in the brain may explain the mechanism of kyotorphin-induced hypothermia. However, there was little evidence of involvement of opioid receptors. The present study demonstrates a potent action of kyotorphin and its analog on thermoregulation.

Analgesics↗
PubMedDate not supplied

A comparison of the antinociceptive and behavioral effects of D-Arg substituted dipeptides and tetrapeptides in mice.

Intracerebroventricular administration of D-Arg substituted dipeptides, H-Tyr-D-Arg-OMe and H-Tyr(Et)-D-Arg-OMe, and D-Arg2 substituted N-terminal tetrapeptides of dermorphin, H-Tyr-D-Arg-Phe-Gly-OEt and H-Tyr(Et)-D-Arg-Phe-Gly-OEt resulted in dose-related and naloxone-reversible antinociceptive effects. Among them, tetrapeptides not only exhibited much more potent and prolonged activities than dipeptides but also were significantly antagonized even by a low dose of naloxone. Spontaneous motor activity was lowered by dipeptides throughout the observation period, which was scarcely antagonized by naloxone. Tetrapeptides elicited locomotor hyperactivity following an initial locomotor suppression. Only the locomotor hyperactivity was significantly antagonized by naloxone. These results suggest that tetrapeptides induce the effects via opioid receptors, whereas the effects of dipeptides are involved in various systems non-specifically.

Animals↗
PubMedDate not supplied

Antinociceptive cross-tolerance between [D-Arg2]-dermorphin tetrapeptide analogs and morphine.

Cross-tolerance between [D-Arg2]-dermorphin tetrapeptide analogs and morphine with respect to antinociception was examined in the present set of experiments. Systemic administration of H-Tyr-D-Arg-Phe-Gly-NH2 (TDAPG-NH2), H-Tyr-D-Arg-Phe-beta-Ala-OH (TDAPA) or morphine over a period of 5 days produced the development of tolerance. In the cross-tolerance study, antinociception after subcutaneous (SC), intracerebroventricular (ICV) and intrathecal (IT) administrations of TDAPG-NH2 and TDAPA in morphine-tolerant mice was not significantly different from their respective effects in saline-pretreated control mice. A marked tolerance to SC- and ICV-administered morphine was seen in mice made tolerant to TDAPG-NH2 and TDAPA. However, IT administration of morphine produced no significant decrement in the antinociceptive activity in mice made tolerant to TDAPG-NH2 and TDAPA. These data indicate that [D-Arg2]-dermorphin tetrapeptide analogs can produce significant antinociception in morphine-tolerant mice.

Amino Acid Sequence↗
PubMedDate not supplied

Differential effects of yohimbine, naloxone and 8-OH-DPAT on ejaculatory response in male dogs.

The aim of this study was to compare the effects of the alpha(2)-adrenergic-receptor antagonist yohimbine, the 5-HT(lA)-receptor agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) and the opioid-receptor antagonist naloxone (all of which have been shown to stimulate male sexual arousal/motivation in rats) on sexual responses in male dogs. Sexual responses (i.e., ejaculation, penile erection and pelvic thrusting behavior) were elicited by manual penile stimulation. Systemic administration of yohimbine (0.03-1.0 mg/kg) produced a biphasic dose response curve for the amount of ejaculated semen collected during genital stimulation (for 5 min), whereas 8-OH-DPAT (0.03-0.3 mg/kg) dose-dependently decreased the amount of ejaculated semen. Thus, yohimbine increased the amount of ejaculated semen at lower doses (0.03-0.3 mg/kg), but decreased it at the highest dose (1.0 mg/kg). The highest dose of yohimbine (1.0 mg/kg) and 8-OH-DPAT (0.3 mg/kg) also produced a significant delay of onset in both ejaculation and penile erection latency (time from starting the stimulation to the first ejaculation and full erection), and a decrease in the incidence of pelvic thrusting behavior. In contrast, administration of naloxone (0.03-1.0 mg/kg) did not affect the sexual responses elicited by genital stimulation. These results indicate that yohimbine and 8-OH-DPAT, but not naloxone, affect sexual responses, particularly ejaculation, and that the drugs which stimulate the mechanisms regulating sexual arousal/motivation in male rats do not show identical effects for sexual function in male dogs. The present findings also confirm our previous observations that the ejaculatory capacity in dogs can be stimulated by lower doses of yohimbine, as evidenced by an increase in the amount of ejaculated semen.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMedDate not supplied

On the brain monoaminergic systems relatint to ejaculation. II. Brain serotonin and ejaculation.

The effects of 5-HTP and pCPA on manually induced ejaculation in dogs and on brain monoamines in dogs and rats were investigated. From the results obtained in this study it was concluded that the serotonergic system in the brain is the mechanism which inhibits the occurrence of ejaculation. Considered together with the results obtained in our previous paper, it is though that ejaculation occurs with the reconciliation of the dopaminergic and serotonergic systems.

5-Hydroxytryptophan↗