Cooperative enhancement of water binding to crownophane by multiple hydrogen bonds: analysis by high level ab initio calculations.

The intermolecular interaction energy of the model system of the water-crownophane complex was analyzed. The water molecule has four hydrogen bonds, with the two hydrogen-donating phenolic hydroxy groups and two hydrogen-accepting oxygen atoms of the poly-oxyethylene chain of the crownophane in the complex. The MP2/6-311G(2d,2p) level calculations of the model system of the complex (hydrogen donating unit + hydrogen accepting unit + water) indicate that the binding energy of the water is 21.85 kcal/mol and that the hydrogen bond cooperativity increases the binding energy as much as 3.67 kcal/mol. The calculated interaction energies depend on the basis set, while the basis set dependence of the cooperative increment is negligible. Most of the cooperative increment is covered by the HF level calculation, which suggests that the major source of the hydrogen bond cooperativity in this system has its origin in induction. The BLYP/6-311G** and PW91/6-311G** level interaction energies of the model system are close to the MP2/6-311G** interaction energies, which suggests that the DFT calculations with these functionals are useful methods to evaluated the interactions of hydrogen bonded systems.

Separation of aromatic isomers on cyclophane-bonded stationary phases.

A cyclophane (CP66)-bonded silica gel stationary phase (CP66-SP) was prepared and the retention of water-insoluble hydrophobic compounds on it was investigated in comparison with that on the CP44-bonded stationary phase (CP44-SP) reported previously. Like CP44-SP, it retained aromatic compounds more strongly than the corresponding alicyclic compounds, as was expected by the cavity size of the cyclophane. The CP66-SP also showed isomer-selectivity for monosubstituted and disubstituted naphthalenes, but its selectivity was perfectly reversed to that of the CP44-SP. On the CP66-SP, isomers having methyl and ethyl groups at beta-position were eluted prior to those having groups at alpha-position, whereas on the CP44-SP beta-substituted naphthalenes were retained more strongly than alpha-substituted ones. Isomers of three- and four-ring aromatic compounds were also separated on these cyclophane-bonded stationary phases. The retention order on the CP66-SP was almost opposite to that on the CP44-SP; on the CP66-SP, the retention order was phenanthrene > anthracene, and chrysene > 1,2-benzanthracene > 2,3-benzanthracene, whereas on the CP44-SP, anthracene > phenanthrene, and 2,3-benzanthracene > chrysene > 1,2-benzanthracene. The retention mechanism of aromatic compounds is discussed on the basis of the structure of the cyclophane-involved complex.

Effects of idebenone on metabolism of monoamines and cyclic AMP formation in rats.

Idebenone, 6-(10-hydroxydecyl)-2,3-dimethoxy-5-methyl-1,4-benzoquinone, at a dose of 100 mg/kg (i.p.) markedly increased the level of 5-hydroxyindole-3-acetic acid (5-HIAA) in several brain regions without affecting monoamine contents in normal rats. In rats with cerebral ischemia, idebenone (10 mg/kg, i.p.) normalized the decreased levels of 5-HIAA in the cerebral cortex, hippocampus, diencephalon and brain stem. A 5-hydroxytryptamine (serotonin, 5-HT) biosynthesis inhibitor, DL-p-chlorophenylalanine (PCPA, 150 mg/kg, i.p.) decreased the levels of 5-HT to one-third of the control level 24 h after administration. Idebenone (10, 30, or 100 mg/kg, i.p.), administered 24 h after the treatment with PCPA, accelerated the PCPA-induced 5-HT decreased in the hippocampus, diencephalon and brain stem in a dose-dependent manner. Idebenone (100 mg/kg, i.p.) stimulated the release of 5-HT in the dorsal hippocampus as determined by in vivo differential pulse voltammetry. Idebenone, like p-chloroamphetamine (PCA), stimulated 5-HT release from slices of hippocampus and diencephalon, and the formation of cyclic AMP in a concentration-dependent manner in rat diencephalon slice. This stimulation was almost completely blocked by methysergide, a 5-HT receptor blocker. Idebenone slightly and PCA markedly inhibited 5-HT uptake into hippocampus slices. The mechanism of the 5-HT releasing actions of idebenone in the hippocampal slices may be mediated through endogenous calcium. These results suggest that idebenone has an enhancing effect on the turnover of 5-HT in the hippocampus, diencephalon, and brain stem of rats.

Idebenone improves learning and memory impairment induced by cholinergic or serotonergic dysfunction in rats.

The effects of idebenone, a cerebral metabolic enhancer, on learning and memory impairment in two rat models with central cholinergic or serotonergic dysfunction were investigated using positively reinforced learning tasks. A delayed alternation task using a T maze was employed to test the effect of idebenone on short-term memory impairment induced by a cholinergic antagonist, scopolamine. A correct response, defined as a turn toward the arm opposite to that in the forced run, was rewarded with food pellets. Scopolamine (0.2 and 0.5 mg/kg, i.p.) significantly decreased the correct responses to the chance level in the 60-s-delayed alternation task. The scopolamine (0.2 mg/kg, i.p.)-induced impairment of short-term memory was improved by idebenone (3-30 mg/kg, i.p.) or an acetylcholinesterase inhibitor, physostigmine (0.1 and 0.2 mg/kg, i.p.), administered simultaneously. The central serotonergic dysfunction model was produced by giving rats a diet deficient in tryptophan, a precursor of serotonin. The rats fed on a tryptophan-deficient diet (TDD) showed a slower learning process in the operant brightness discrimination task (mult V115 EXT) than did rats fed on a normal diet. Idebenone (60 mg/kg/day) admixed with the TDD decreased the number of lever-pressing responses emitted during the extinction periods. The percentage of correct responses was significantly higher in the idebenone-treated group than in the control TDD group. These results suggest that idebenone may improve both the impairment of short-term memory induced by a decreased cholinergic activity and the retardation of discrimination learning induced by central serotonergic dysfunction.

Effects of idebenone on memory impairment induced in ischemic and embolization models of cerebrovascular disturbance in rats.

Two rat models of memory impairment in passive avoidance learning induced by cerebrovascular disturbance, were established to estimate the effects of a cerebral metabolic enhancer, idebenone. Transient and global cerebral ischemia in rats, produced by 4-vessel occlusion for 200 s immediately after the acquisition trial of passive avoidance learning, shortened the latencies in the retention test trial performed 24 h later. This retrograde amnesia was reversed significantly by idebenone administered orally or intraperitoneally at the doses of 10 and 30 mg/kg before the retention test trial. Idebenone at a dose of 10 mg/kg, given intraperitoneally before or immediately after the ischemia, also markedly inhibited the appearance of amnesia. In the second model, permanent and cerebral hemisphere embolization produced by injecting 2,000 microspheres into the internal carotid artery, significantly impaired passive avoidance learning performed 7 days later. The repeated administration of idebenone (30 mg/kg, i.p.). once a day after the embolization, significantly improved the impairment of passive avoidance learning in the embolized rats. Furthermore, physostigmine and arginine-vasopressin as reference compounds improved the impairment of passive avoidance learning in these models. These findings suggest that idebenone ameliorates memory impairment induced by cerebral vascular disturbance in rats.

[Effect of thyrotropin-releasing hormone (TRH) and its analog DN-1417 on scopolamine-induced impairment of short-term memory in rats].

The effects of a few drugs, which are known to activate central nervous system, on scopolamine-induced impairment of short-term memory (STM) were studied in a delayed alternation task in rats. Rats were initially trained using a delayed alternation task in which a forced run to one arm of a T-maze was followed by a free-choice run. A correct free-choice response was defined as a turn toward the arm opposite to that in the forced run, and was rewarded with food pellets. After repeated training of the 60 sec-delayed alternation task, the treatment with scopolamine (0.2 mg/kg, ip) at 20 min before the test resulted in a significant decrement in the correct response. The scopolamine-induced impairment of STM was significantly antagonized by DN-1417 (10 mg/kg, ip) given 1 hr before the test. However, TRH (3-30 mg/kg, ip) and methamphetamine (0.2-1.0 mg/kg, ip) did not improve the scopolamine-induced impairment in the task. In rats without treatment with scopolamine, these drugs did not affect the percent correct response. These results suggest that DN-1417 may have an improving effect on the impairment of STM induced by a decreased cholinergic activity.

Cerebral embolization leads to memory impairment of several learning tasks in rats.

The effects of cerebral embolization, produced by injecting microspheres into the left internal carotid artery, on passive and active avoidance tasks and water filled multiple T-maze task, were studied in male Wistar rats. The rats with cerebral embolization were markedly impaired acquisition and retention of the one-trial passive avoidance response. The impairment depended on the number of microspheres injected and continued for 2 weeks. The cerebral embolized rats were also impaired acquisition of two-way active avoidance response in a shuttle box. These impairments are not due to decrease in shock sensitivity, because there was no significant change in the flinch-jump threshold. The embolized rats also exhibited a significant disturbance in performance of water filled multiple T-maze learning. These results suggest that rats with cerebral embolization are impaired in three different types of learning tasks, and may be useful as an animal model for the vascular type of dementia.

Age-related changes in learning and memory in the senescence-accelerated mouse (SAM).

Age-related changes in learning ability were studied in senescence-accelerated mice (SAM) reared under specific pathogen-free (SPF) conditions. SAM-P/8/Ta (SAM-P/8, senescence-prone substrain) showed an age-associated increase in spontaneous motor activity (SMA) compared with SAM-R/1/Ta (SAM-R/1, senescence-resistant substrain) in a novel environment when the activity was measured in the light period, although there was no significant difference in the dark period. In observations of the circadian rhythm of SMA, SAM-P/8 showed a significant increase in diurnal SMA. In SAM-P/8 mice, the acquisition of passive avoidance response was slightly but significantly impaired even at 2 months of age, compared with SAM-R/1 control; the impairment became obvious with aging. In a one-way active avoidance task, SAM-P/8 did not show any impairment in the acquisition of avoidance response at 2 and 4 months of age. However, significant impairment was observed in SAM-P/8 at 12 months of age. The impairments of avoidance tasks were not due to a decrease in shock sensitivity, as indicated by no significant change in the flinch-jump threshold. In a water-filled multiple T-maze task, there was no difference in the number of errors between the two groups. With regard to the performance time to reach the goal, however, SAM-P/8 showed a mild prolongation at 2 months of age, and the prolongation became marked with advancing age.(ABSTRACT TRUNCATED AT 250 WORDS)

A possible mechanism of action of thyrotropin-releasing hormone (TRH) and its analog DN-1417 on the release of dopamine from the nucleus accumbens and striatum in rats.

Slices of the nucleus accumbens, the terminus of the mesolimbic dopaminergic system and the striatum, the terminus of the nigrostriatal dopaminergic system obtained from rats, were used for analyzing the dopamine releasing effects of TRH and its analog DN-1417 (gamma-butyrolactone-gamma-carbonyl-L-histidyl-L-prolinamide citrate). (1) Dopamine release: The addition of DN-1417 (5 X 10(-5) M) or TRH (5 X 10(-4) M) stimulated the release of prelabelled [3H]-dopamine (DA) from the superfused nucleus accumbens slices, and 100 or 20 times higher concentrations of each compound stimulated DA release from the striatal slices. The omission of Ca2+ from the superfusion medium or the addition of ouabain (5 X 10(-3) M), a (Na+ + K+) stimulated adenosine triphosphate (ATP) phosphohydrolase [(Na+ + K+)-ATPase] inhibitor, almost completely abolished the DN-1417- or TRH-induced DA releasing effect. (2) 45Ca2+ uptake: The addition of DN-1417 (10(-4) M) or TRH (10(-4) M) stimulated 45Ca2+ uptake into the nucleus accumbens slices in a time-dependent manner from 1 to 5 min at 30 degrees C. On the other hand, both drugs (10(-4) M) had no effect on 45Ca2+ uptake into the striatal slices. A Ca2+ ionophore, A-23187 (10(-6) M), stimulated 45Ca2+ uptake into slices of the nucleus accumbens and striatum. Ouabain abolished the DN-1417-, TRH- and A-23187-induced effects. (3) Cyclic AMP formation: The addition of DN-1417 (10(-4) M) or TRH (10(-4) and 10(-3) M) accelerated cyclic AMP formation in the nucleus accumbens, but not in the striatal slices. A Ca2+ antagonist, methoxyverapamil (D-600, 10(-6) M) almost completely abolished the DN-1417- and TRH-effects. (4) (Na+ + K+)-ATPase activity: The addition of DN-1417 (10(-5) and 10(-4) M) or TRH (10(-4) M) activated (Na+ + K+)-ATPase in the P1 fraction (cell debris, nuclei) of the nucleus accumbens, but had little effect on the same activity in the striatum. (5) [3H]-TRH binding: The addition of 10(-6) to 10(-4) M of DN-1417 and TRH inhibited concentration-dependently [3H]-TRH binding in the nucleus accumbens and striatal slices. Ouabain (5 X 10(-3) M) almost completely abolished [3H]-TRH binding in both types of slices.(ABSTRACT TRUNCATED AT 400 WORDS)

[Effect of idebenone on scopolamine-induced impairment of short-term memory in rats].

The effects of a novel compound, idebenone [6-(10-hydroxydecyl)-2, 3-dimethoxy-5-methyl-1, 4-benzoquinone] and cholinergic drug on short-term memory (STM) were studied in a delayed alternation task in rats. Rats were initially trained using a delayed alternation task in which a forced run to one arm of a T-maze was followed by a free-choice run. A correct free-choice response was defined as a turn toward the arm opposite to that in the forced run, and was rewarded with food pellets. When the time interval between the forced run and free-choice run was longer than 60 sec, the correct responses decreased by about 30% compared with that in no delay trials. After repeated training of the 60 sec-delayed alternation task, the effect of an anticholinergic drug scopolamine (0.1-0.5 mg/kg, ip) on the delayed alternation task was tested. The drug administered 20 min before the test significantly decreased the correct responses in a dose dependent manner. The effect of scopolamine (0.2 mg/kg, ip) was antagonized by the simultaneous administration of physostigmine (0.05-0.2 mg/kg, ip) in a dose dependent manner. Furthermore, physostigmine (0.1 and 0.2 mg/kg, ip) alone increased correct responses in the same task. Idebenone (3-30 mg/kg, ip), administered simultaneously with scopolamine, significantly improved the scopolamine-induced decrement of correct responses, with the highest efficacy at 10 mg/kg. The compound alone did not affect the number of correct responses. These results suggest that STM is closely related to the cholinergic system, and that idebenone may have an improving effect on the impairment of STM induced by a decreased cholinergic activity.

[Pharmacological actions of iprazochrome on the vascular system].

The pharmacological actions of iprazochrome (IC) on the vascular system were studied, and the following results were obtained: No death nor abnormal behaviors were observed in acute toxicity tests conducted on male and female mice and rats despite the administration of large doses of IC (10,000 mg/kg, p.o. and 80 mg/kg, i.v., respectively). IC inhibited dose-dependently platelet aggregation in vitro induced by arachidonate and ADP, whereas no effect was observed on ADP-induced respiratory depression in mice, which is closely related to platelet aggregation in vivo. The antiserotonergic actions of IC on the isolated external carotid arteries and femoral arteries in dogs observed in a noncompetitive manner were found to be 1/24 to 1/65 that of methysergide. On the other hand, IC showed no inhibitory effect on the paw edema of rats in vivo induced by serotonin. The inhibitory effect of IC on peritoneal dye leakage in mice was less than half that of phenylbutazone. IC prevented apoplexy in stroke-prone SHR (SHRSP) without lowering the blood pressure. Histological changes in the cerebrum of SHRSP were ischemic changes such as swelling of the neurons and shrinkage of the nuclei, mainly in the cerebral cortex and corpus striatum area.

[A TRH analog (DN-1417). Antagonistic effects on reserpine-induced decreases in local cerebral glucose utilization and cerebral monoamine levels].

Thyrotropin-releasing hormone (TRH) and its analog, DN-1417 (gamma-butyrolactone-gamma-carbonyl-L-histidyl-L-prolinamide citrate), significantly antagonized against reserpine-induced reduction of the spontaneous motor activity and the electroconvulsive threshold in mice. To search for sites of action and mechanisms, effects of DN-1417 on reserpine in local cerebral glucose utilization (LCGU) and cerebral monoamine levels were also investigated in rats. Reserpine (2 mg/kg, i.p., 24 hr pretreatment) reduced LCGU and the levels of cerebral monoamine in all the brain regions. DN-1417 (5 mg/kg, i.v.) significantly reversed the reduction of LCGU induced by reserpine in the thalamus dorsomedial nucleus, mamillary body, septal nucleus, caudate-putamen and nucleus accumbens. The effects of DN-1417 were completely abolished by pretreatment with a dopaminergic (DA) and a serotonergic (5-HT) receptor blocker, pimozide (1 mg/kg) and methysergide (5 mg/kg), respectively. DN-1417 (20 mg/kg, i.p.) reversed 5-HT level in the hypothalamus depleted by reserpine. These results suggest that the antagonistic effects of DN-1417 against reserpine-induced reduction of the locomotor activity and the electroconvulsive threshold seem to be mediated by DA- and 5-HT-ergic activations mainly in the nucleus accumbens and hypothalamus, respectively.

[Effect of TRH and its analog DN-1417 on anoxia-induced amnesia in mice].

The effect of neuropeptides and their analogs on anoxia-induced amnesia was examined using one-trial passive avoidance task in mice. Anoxia, produced by the exposure to CO2 immediately after the acquisition of avoidance response, induced amnesia which is shown by a short latency to enter from the safety compartment into the shocked compartment in the retention test conducted 24 hr later. In these anoxia-treated animals, thyrotropin-releasing hormone (TRH: 10-20 mg/kg), its analog DN-1417 (10-20 mg/kg) and ACTH 4-10 (66 micrograms/body), which were given sc 15-60 min before the retention test, markedly prolonged the latency in a dose-dependent manner, indicating a reversal of the amnesia. Arginine- and lysine-vasopressin also reversed the amnesia at a dose of 100 micrograms/body. These results suggest that TRH and DN-1417, known to reverse the amnesia produced by the protein synthesis inhibitor cycloheximide, have ameliorating effects on the retrieval process of memory.

[A TRH analog (DN-1417). Effects on the levels of monoamines and the metabolites in the various brain regions in rats].

The effects of a TRH (thyrotropin-releasing hormone) analog, DN-1417 (gamma-butyrolactone-gamma-carbonyl-L-histidyl-L-prolinamide citrate), on the levels of norepinephrine (NE), dopamine (DA), serotonin (5-HT) and the metabolites in the various brain regions of rats were determined by means of high performance liquid chromatography with electrochemical detection. DN-1417 (20 mg/kg, i.p.) produced marked decreases in the levels of NE, DA and 5-HT, especially in the nucleus accumbens, striatum and hypothalamus. The maximum effect was observed at 15 min after the administration. DA metabolites, 3,4-dihydroxyphenylacetic acid and homovanillic acid, increased significantly in the nucleus accumbens, striatum and hypothalamus, whereas 3-methoxy-4-hydroxyphenylglycol and 5-hydroxyindoleacetic acid remained unchanged. 3-Methoxytyramine increased significantly in the nucleus accumbens and striatum. Two week chronic administration of DN-1417 (20 mg/kg, i.p.) increased the levels of DA and NE in the nucleus accumbens and DA in the striatum. These results suggest that DN-1417 stimulates the turnover of the cerebral monoamines, especially the release of DA from the nucleus accumbens and striatum in the mesolimbic and nigro-striatal DAergic systems.

[A TRH analog (DN-1417). Anti-reserpine action in electroconvulsive threshold and involvement of serotonergic (5-HT) mechanism in mice].

The antagonistic effect of a TRH (Thyrotropin-releasing hormone) analog, DN-1417 (gamma-butyrolactone-gamma-carbonyl-L-histidyl-L-prolinamide citrate) against reserpine-induced reduction of electroconvulsive threshold (EC50) and the involvement of monoaminergic mechanism were studied in mice. Reserpine (2 mg/kg, i.p.) reduced the EC50 to 55-77% of the control in association with the depletion of brain monoamine. TRH and DN-1417 significantly reversed the EC50 reduced by reserpine. DN-1417 partially recovered 5-HT level and increased in the brain levels of 3-methoxy-4-hydroxyphenylglycol, homovanillic acid and 5-hydroxyindoleacetic acid in reserpinized mice. Monoaminergic receptor blockers attenuated, but muscarinic blockers accelerated the antagonistic effects of DN-1417 on the EC50. Neither alpha-methyl-p-tyrosine nor FLA-63 inhibited the effects of DN-1417, whereas p-chlorophenylalanine not only inhibited the antagonistic effect of DN-1417 on the EC50 but also prevented the stimulation effect on 5-HT turnover. Therefore, the antagonistic effect of DN-1417 against reserpine on the EC50 is most likely mediated by the stimulation of monoamine turnover, especially 5-HT in mice.

[A TRH analog (DN-1417). Blood level and brain distribution determined by radioimmunoassay after intravenous administration in rats].

Thyrotropin-releasing hormone (TRH) and its analog, DN-1417 (gamma-butyrolactone-gamma-carbonyl-L-histidyl-L-prolinamide citrate), were administered intravenously to rats, and the blood level and brain distribution were determined by a specific radioimmunoassay. Degradation half-life of DN-1417 in the brain homogenate and blood was 27.5 min and those of TRH were 5 and 7.5 min, respectively. After the administration of DN-1417 (0.625, 2.5 and 10 mg/kg), the blood levels of immunoreactive-DN-1417 exhibited an apparent two compartment open model. The half-life values of the alpha- and beta-phase were 3 approximately 7 and 15 approximately 22 min, respectively. The half-life of the blood level of immunoreactive-DN-1417 was 2 approximately 3 times longer than that of TRH. As a result, the area under the curve of DN-1417 was 2.5 approximately 6 times larger than that of TRH. Blood level of immunoreactive-2-hydroxy-4-carboxybutyryl-histidyl-prolinamide+ ++ (DN-COOH), a main metabolite of DN-1417, was not more than 1% of the immunoreactive DN-1417 level. The distribution of DN-1417 into whole brain was attained its peak at 1 approximately 2 min after the administration. The percentage of transported DN-1417 into the brain at peak time was 0.062-0.163% of each of the doses administered. After the administration of DN-1417 (2.5 mg/kg), the pituitary, nucleus accumbens and hypothalamus showed higher concentrations, while the striatum showed the lowest concentration in the brain tissue examined.

Effects of idebenone (CV-2619) on metabolism of monoamines, especially serotonin, in the brain of normal rats and rats with cerebral ischemia.

The effects of 6-(10-hydroxydecyl)-2,3-dimethoxy-5-methyl-1,4-benzoquinone (idebenone, CV-2619) on the contents, turnover, release and uptake of monoamines, especially serotonin (5-HT), in various brain regions of Wistar rats were studied in vivo and in vitro. In normal rats, an intraperitoneal (i.p.) dose of 100 mg/kg of CV-2619 had no significant effect on the levels of norepinephrine (NE), dopamine (DA) and their metabolites, and 5-HT in the brain regions examined, but it increased the levels of 5-hydroxyindole-3-acetic acid (5-HIAA), the main metabolite of 5-HT, in many brain regions. In rats with cerebral ischemia, a low dose (10 mg/kg, i.p.) of CV-2619 normalized the decreased levels of 5-HIAA in the cerebral cortex, hippocampus, diencephalon and brain stem. A 5-HT biosynthesis inhibitor, DL-p-chlorophenylalanine (PCPA, 150 mg/kg, i.p.), decreased the levels of 5-HT in all brain regions to one-third of the control levels 24 hr after administration in normal rats. CV-2619 (10, 30 or 100 mg/kg, i.p.), administered 24 hr after the treatment with PCPA, accelerated the PCPA-induced 5-HT decreases in the hippocampus, diencephalon and brain stem in a dose-dependent manner. In vitro CV-2619, like p-chloroamphetamine (PCA), stimulated 5-HT release from slices of the hippocampus and diencephalon. CV-2619 slightly inhibited and PCA markedly inhibited 5-HT uptake into hippocampal slices. The mechanism of the 5-HT releasing action of CV-2619 in hippocampal slices seems to be mediated through endogenous calcium. These results suggest that CV-2619 has an enhancing effect on the turnover of 5-HT in the hippocampus, diencephalon and brain stem of rats.

[Pharmacological study of the temporary cerebral ischemic rats produced by bilateral vertebral and carotid artery occlusion. Effects of DN-1417].

We investigated the ameliorating effects of DN-1417 (a TRH analog) on the changes of behavior, EEG, neurochemical parameters and regional cerebral blood flow (rCBF) in rats with global cerebral ischemia. Global cerebral ischemia was produced by 10-min occlusion of both common carotid arteries 24 hr after the permanent electrocauterization of bilateral vertebral arteries. DN-1417 was administered intraperitoneally as soon as possible, following recirculation of carotid blood flow. DN-1417 shortened significantly the recovery times of righting reflex (RR) and spontaneous movement (SM) at 2.5 mg/kg and higher doses, and it recovered effectively the EEG activity at 10 mg/kg during recirculation after 10-min cerebral ischemia. In addition, DN-1417 (10 mg/kg) recovered the various changes such as decrease of 5-hydroxytryptamine (5-HT) levels, increase of cyclic AMP (cAMP) levels, inhibition of [3H]-choline uptake, depression of choline acetyltransferase (CAT) and acetylcholine esterase (AChE) activities, and shortened the durations of hyperperfusion and hypoperfusion of rCBF. As a result, it is identified that DN-1417 ameliorates the disturbance of consciousness supposedly caused by behavioral and EEG abnormalities during recirculation following the temporary cerebral ischemia, and the effect of DN-1417 seems to be mediated by normalizing of alterations in the brain monoaminergic and cholinergic systems, as well as rCBF, and the effectiveness for disturbance of consciousness in clinical situations would be expected.

[Regional cerebral blood flow in rats with cerebral ischemia produced by bilateral vertebral and carotid artery occlusion].

Regional cerebral blood flow (rCBF) was measured prior to, during and after global cerebral ischemia in rats. Global cerebral ischemia was produced by 10 or 30-min occlusion of both common carotid arteries which was done 24 hr after the permanent electrocauterization of bilateral vertebral arteries. The rCBF was measured using the radioactive microsphere technique. In rats subjected to 10-min cerebral ischemia, rCBF in 9 brain regions was reduced to 11.3-54.8% (mean: 26.9%) of that of the sham operated control. Ten min after recirculation, hyperperfusion was observed in the cerebral cortex, hippocampus and striatum, and a moderate recovery was detected in the n.accumb. + olfactory tub., thalamus and hypothalamus. However, rCBF in these 6 regions was again decreased 20-30 min later, and it recovered to levels more than 50% of the control 60 min after the ischemic event. In the other 3 regions (cerebellum, colliculus sup. + inf., pons + medulla), rCBF increased toward the control level gradually, and it completely recovered 60 min after recirculation. On the other hand, in rats subjected to 30-min cerebral ischemia, rCBF in 9 brain regions was reduced to 1.77-26.3% (mean: 9.6%) of that of the control. The post-ischemic hyperperfusion in the cerebral cortex and hippocampus and a moderate recovery of rCBF in the striatum and n.accumb. + olfactory tub. were observed 10 min after the cerebral ischemia. However, rCBF in these 4 regions remained under the control levels from 20 to 60 min after recirculation.(ABSTRACT TRUNCATED AT 250 WORDS)

[TRH and its analog (DN-1417). Effects on central dopaminergic system-dependent behaviors in rats and mice].

Effects of TRH and its analog, gamma-butyrolactone-gamma-carbonyl-histidyl-prolinamide citrate (DN-1417), on circling, stereotyped or climbing behavior were investigated in rats and mice. High doses of TRH (100 mg/kg, i.p.) and DN-1417 (20-50 mg/kg, i.p.) produced a significant ipsilateral circling behavior in rats with the lesions of the unilateral dopamine (DA) pathway by 6-hydroxydopamine. In intact mice, stereotyped sniffing accompanying hyperactivity was caused at low doses of TRH or DN-1417 (1-20 mg/kg, i.p.), and stereotyped licking behavior was observed at high doses of TRH or DN-1417 (20-200 mg/kg, i.p.). Furthermore, TRH, DN-1417 or methamphetamine caused a dose-related climbing behavior in mice pretreated with L-DOPA and Ro 4-4602. Circling behavior, stereotyped sniffing or licking behavior induced by TRH or DN-1417 was markedly suppressed by pretreatment with pimozide or alpha-methyltyrosine. However, atropine and scopolamine potentiated the circling inducing action of TRH or DN-1417, in contrast with suppression of the licking behavior. These results suggest that TRH and DN-1417 produce circling, sniffing, licking and climbing behaviors via activation of the central DA system, and that cholinergic mechanisms may be also involved in licking behavior induced by TRH or DN-1417.