Comparison of antiemetic efficacy between single and repeat treatment with dexamethasone in patients receiving carboplatin-based combination chemotherapy

A retrospective study was carried out to compare the preventive effects of single and repeat treatment with dexamethasone (DEX) on delayed nausea and emesis in patients who had received carboplatin (CBDCA)-based combination chemotherapy. Sixty-four patients were evaluated. Efficacy was assessed using the nausea and emesis score, food intake score and the requirement for antiemetic medication. These forward scores were categorized as three-grade during the first 5 days after chemotherapy. Acute nausea and emesis were well controlled in both groups on day 1. Mean values of the nausea and emesis score on day 3 evening and the food intake score on day 4 morning in the repeat-treatment group was 1.31 ± 0.93 and 3.46 ± 1.03, respectively, which were significantly better when compared with the single-treatment group (2.00 ± 1.52; P = 0.028 and 2.79 ± 1.12; P = 0.018, respectively). Multivariate logistic regression analysis revealed that less frequent dispensing of antiemetic medication was significantly associated with the repeat-treatment group (adjusted odds ratio, 0.153; 95% confidence interval, 0.026-0.734; P = 0.018). These results suggest that repeat-dose DEX may be more effective than single-dose DEX for the prevention of delayed nausea and emesis after CBDCA-based combination chemotherapy.

Behavioral pharmacological properties after recovery from the loss of righting reflex induced by benzodiazepine receptor agonists in mice

In this study we examined the behavioral pharmacological side effects after recovery from the loss of righting reflex induced by three benzodiazepine receptor agonists - zolpidem, brotizolam and flunitrazepam - in ddY mice. All agents caused marked motor incoordination in the rotarod test and muscle flaccidity in the traction test until 15 min after recovery of righting reflex. Thereafter, the short-acting hypnotics zolpidem and brotizolam showed a faster recovery than the long-acting benzodiazepine flunitrazepam. However, head twitch responses were observed in the mice treated with flunitrazepam, but zolpidem and brotizolam had no such effect. The flunitrazepam-induced head twitch response was antagonized by ketanserin, a 5- HT(2A) receptor antagonist. These results indicate that flunitrazepam, a long-acting benzodiazepine that is nonselective for type I and II benzodiazepine receptors, induces head twitch responses with muscle flaccidity after recovery from the loss of righting reflex caused by these drugs. In addition, these findings suggest the involvement of a 5-HT(2A)-GABA(A) receptor/benzodiazepine interaction in this phenomenon.

Topical application of royal jelly has a healing effect for 5-fluorouracil-induced experimental oral mucositis in hamsters

The aim of this study was to evaluate the effects of bee products such as honey, royal jelly and propolis on 5-fluorouracil-induced experimental oral mucositis in hamsters. Oral mucositis was induced in hamsters through a combination of 5-fluorouracil and mild abrasions that were made on the cheek pouch. Honey, royal jelly and propolis were thereafter topically administered to the oral mucosa, and then the healing process was examined by measuring the size of the mucositis. Honey (1%, 10% and 100%) and propolis (0.3%, 1% and 3%) ointments did not reduce the size of the mucositis in comparison to the vaseline-treated control group. However, the royal jelly (3%, 10% and 30%) ointments significantly improved the recovery from 5-fluorouracil-induced damage in a dose-dependent manner. These results suggest the possibility that the topical application of royal jelly has a healing effect on severe oral mucositis induced by chemotherapy.

Changes in the plasma diazepam concentration and its anticonvulsant effect after the discharge of a diazepam suppository from the rectum in rats

One of the clinical problems regarding the use of suppositories for patients is the discharge of the medication itself after the insertion of the suppository. The effects of the discharge of diazepam (DZP) suppositories from the rectum on the plasma DZP concentration and its anticonvulsant action were investigated in rats. The plasma DZP concentration reached a maximum at approx. 30 min after the rectal administration of a 5 mg/kg DZP suppository. The discharge of the DZP suppository from the rectum at 5 or 10 min after rectal administration significantly reduced the plasma DZP concentration and the anticonvulsant action of the DZP suppository against pentylenetetrazol-induced seizures. However, when the suppository was discharged from the rectum after 20 min, the plasma DZP concentration and the anticonvulsant action were only slightly but not significantly decreased. These results suggest that the discharge of the DZP suppository in the early phase, within 20 min, decreases the plasma concentration and the anticonvulsant action of the DZP suppository in rats. Therefore, when the suppository is discharged from the rectum immediately, sufficient observation and proper treatment are necessary.

Cessation of chronic nicotine administration enhances wet-dog shake responses to 5-HT2 receptor stimulation in rats

RATIONALE

The involvement of central serotonergic systems has been hypothesized clinically to contribute to nicotine withdrawal symptoms. However, involvement of the serotonin2 (5-HT(2)) receptor system in nicotine withdrawal is not clear.

OBJECTIVES

The changes in wet-dog shake responses induced by (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI), a selective 5-HT(2) receptor agonist, following nicotine cessation was investigated in rats.

METHODS

DOI (1 mg/kg SC) was administered 24 h after the final treatment of saline or nicotine (0.5 mg/kg per day SC) for 7 or 21 days.

RESULTS

Cessation of nicotine administration for 7 or 21 days increased DOI-induced wet-dog shake responses. A single administration of nicotine (0.5 mg/kg SC) had no effect on DOI-induced wet-dog shakes. The enhancement by the cessation of nicotine treatment for 7 days was abolished by coadministration of nicotine. Mecamylamine (3 mg/kg IP), a nicotinic receptor antagonist, precipitated DOI-induced wet-dog shake responses in rats chronically treated with nicotine but not with saline.

CONCLUSIONS

These findings suggest that cessation of chronic nicotine produced increased sensitivity to 5-HT(2) receptor systems, and that the 5-HT(2) receptor systems may be involved in the nicotine withdrawal symptoms.

[Assessment of anti-tremorogenic drugs using nicotine-induced tail-tremor model and elucidation of the mechanism]

Repeated administration of nicotine causes a tremor only in the tail (tail-tremor) of rats. The tremor is accompanied with locomotor hyperactivity without rigidity and immobility of the whole body, suggesting the involvement of the mechanism associated with the movement. The tail-tremor induced by nicotine was suppressed by nicotinic acethylcholine (nACh) receptor antagonists, but not by muscarinic acethylcholine (mACh) receptor antagonists. Moreover, the tail-tremor was suppressed by beta-adrenoceptor antagonists and benzodizepines. The tremor at rest is observed only in Parkinson's disease, which is improved by the use of mACh receptor antagonists. An essential tremor is one of the typical tremor connected with the movement (postural tremor) and improved with beta-adrenoceptor antagonists. These findings and results suggest that the nicotine-induced tail-tremor is useful for the study of the essential tremor as an animal model. On the other hand, daily administration of nicotine resulted in an augmentation of the tail-tremor. The development of the tail-tremor was suppressed by nACh receptor antagonists, N-methyl-D-aspartate (NMDA) receptor antagonists and nitric oxide (NO) synthase inhibitors. These results suggest that central nACh receptors are essential for the onset and further development of the tail-tremor induced by repeated administration of nicotine, and that NO formation mediated by NMDA receptors is involved in the developmental mechanisms.

Effect of immobilization stress on anticonvulsant actions and pharmacokinetics of zonisamide in mice

The effects of immobilization stress on anticonvulsant actions and pharmacokinetics of zonisamide were investigated in mice. Oral administrations of zonisamide (10, 20, and 50 mg/kg) dose-dependently reduced incidence of tonic extension (TE) induced by maximal electroshock seizure (MES). Immobilization stress for 2 h immediately after the administration of zonisamide further enhanced the anticonvulsive actions of it. On the other hand, the serum zonisamide concentrations in stressed group were lower during the first 30 min after the administration compared with that in nonstressed control group. Thereafter, there were no significant differences in the serum concentrations between two groups. The brain zonisamide concentration and the concentration ratio of brain/serum at 2 h after administration of zonisamide (50 mg/kg) were significantly higher in stressed group, rather than that in the nonstressed control group without changing the serum concentration. These results suggest that immobilization stress enhances anticonvulsant actions of zonisamide, and that increases of brain zonisamide concentration by immobilization stress may be related with this phenomenon.

Involvement of 5-hydroxytryptamine(1A) receptors in nicotine-induced tail tremor in rats

Involvement of the serotonergic system in tail tremor induced by repeated administration of nicotine was investigated in rats. Tail tremor induced by nicotine (0.5 mg/kg, s.c.) was suppressed by a 5-HT(1A) receptor antagonist, N-¿2-[4-(2-methoxyphenyl)-1-piperazinyl-]ethyl¿-N-(2-pyridinyl)cycloh exanecarboxamide trihydrochloride (WAY-100635; 0.3-3 mg/kg, i.p.), but not by a 5-HT(2) receptor antagonist, ketanserin (0.1-0.3 mg/kg, i.p). The 5-HT(1A) receptor agonists, buspirone (1-20 mg/kg, i.p.), gepirone (1-10 mg/kg, i.p.), tandospirone (1-10 mg/kg, i.p.) and (+/-)-8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT; 0.01-0.1 mg/kg, s.c.), enhanced the tail tremor. The enhancement of tail tremor by buspirone (10 mg/kg, i.p.) was blocked by WAY-100635 (0.3-3 mg/kg, i.p.). These findings suggest that nicotine-induced tail tremor is mediated by 5-HT(1A) receptors and that 5-HT(1A) receptor antagonists are effective in the treatment of tremor.

Inhibition of neuronal dopamine uptake by some antiallergic drugs

The effects of 10 antiallergic drugs (astemizole, azelastine, ebastine, emedastine, epinastine, ketotifen, oxatomide, terfenadine, pemirolast and tranilast) on neuronal dopamine uptake were examined. Some drugs examined showed a concentration-dependent inhibition of [3H]dopamine uptake into synaptosomal preparations of the rat striatum. The inhibition constant (Ki) values were 231-876 nM for ebastine, terfenadine, oxatomide and astemizole. The specific binding of [3H] (1-[2-(diphenylmethoxy)ethyl]-4-(3-phenylpropyl)piperazine) (GBR12935) to the rat striatal membranes was also inhibited by these antiallergic drugs. There was a good correlation between the degrees of inhibition of [3H]dopamine uptake and [3H]GBR12935 binding. Then, the behavioral excitement induced by L-DOPA (100 mg/kg, s.c.) plus pargyline hydrochloride (80 mg/kg, i.p.) in mice was significantly enhanced by i.p. treatment with ebastine (10 mg/kg) and astemizole (5 mg/kg). These results suggest that the neuronal dopamine uptake is inhibited by some antiallergic drugs, especially ebastine.

Steady-state serum concentrations of carbamazepine and valproic acid in obese and lean patients with epilepsy

Steady-state serum concentrations of carbamazepine (CBZ) and valproic acid (VPA) were investigated in normal weight (body mass index; BMI 20 to 25), lean (smaller than 20 BMI) and moderately obese subjects (greater than 25 BMI) who received either 400 mg/day of CBZ or 800 mg/day of VPA. The CBZ serum concentration in lean subjects was significantly higher than that in normal weight subjects. However, no significant differences in VPA serum concentration were found between the three groups. The CBZ serum concentration decreased with increases in total body weight, and the VPA serum concentration decreased with increases in ideal body weight. However, both serum concentrations were not correlated with BMI. These results suggest that VPA doses should be calculated using ideal body weight and that degree of obesity may affect CBZ serum concentration rather than VPA serum concentration.

Repeated mazindol and methamphetamine administration produces cross-sensitization to stereotyped behavior induced by these agents in rats

The cross-sensitization to stereotyped behavior between mazindol (MZD) and methamphetamine (MAP) was investigated in rats. MZD (5 and 10 mg/kg/day, p.o.), MAP (5 and 10 mg/kg/day, p.o.) and saline (1 ml/kg, p.o.) were administered once daily for a week. Challenge with MZD (10 mg/kg, p.o.) on the 8th day caused markedly stereotyped behavior in MAP-pretreated group compared with the saline-pretreated control group. MAP (10 mg/kg, p.o.)-induced stereotyped behavior on the 8th day was also greater in MZD-pretreated group rather than the saline-pretreated control group. These results suggest that repeated MZD and MAP administration cross-sensitizes to their stereotype-producing effects.

Involvement of the central catecholaminergic system in nicotine-induced tail-tremor in rats

The effect of 6-hydroxydopamine on repeated nicotine-induced tail-tremor was investigated in rats. Tail-tremor induced by nicotine (0.5 mg/kg/day, subcutaneously) became more pronounced in intensity with daily administration for 9 days. Rats pretreated with 6-hydroxydopamine (250 micrograms, intracerebroventricularly) showed almost the maximum degree of tail-tremor during the whole experimental period. However, in rats pretreated with 6-hydroxydopamine plus desipramine, enhancement of tail-tremor was slight in the beginning but increased with the daily nicotine administration. Fourteen-day administration of nicotine did not result in significant changes in noradrenaline and dopamine levels in the cortex, hypothalamus, striatum and nucleus accumbens. These results suggest that nicotine-induced tail-tremor is associated with the supersensitivity of postsynaptic catecholaminergic receptors in the central nervous system, and that the noradrenergic system may be more important than the dopaminergic system in this phenomenon.

Involvement of nitric oxide in development of tail-tremor induced by repeated nicotine administration in rats

Daily administration of nicotine (0.5 mg/kg per day s.c.) to rats caused a tremor that appeared only in the tail (tail-tremor) and which became more marked over 8 days. Nitric oxide (NO) synthase inhibitors, Nw-nitro-L-arginine (10 mg/kg per day i.p.) or Nw-nitro-L-arginine methyl ester (20 and 40 mg/kg per day i.p.), administered each day before nicotine attenuated the development of the tail-tremor. However, neither Nw-nitro-L-arginine (2-10 mg/kg i.p.) nor Nw-nitro-L-arginine methyl ester (10-40 mg/kg i.p.) affected the tail-tremor that developed after 14 days of repeated nicotine administration. The noncompetitive N-methyl-D-aspartate (NMDA) receptor antagonist, MK-801 ((+)-5-methyl-10,11,-dihydro-5H-dibenzo[a,b]cyclohepten-5,10-imine hydrogen maleate) at 0.2 mg/kg per day (i.p.), or competitive antagonist, CPP (3-[(+/-)-2-carboxypiperazin-4-yl] propyl-1-phosphonic acid) at 2 mg/kg per day (i.p.), administered each day before nicotine attenuated the development of the tail-tremor. MK-801 (0.01-0.2 mg/kg i.p.) but not CPP (0.5-4 mg/kg i.p.) suppressed the tail-tremor that developed after 14 days of repeated nicotine administration. These results suggest that NO formation mediated by NMDA receptors is involved in the mechanisms underlying the tail-tremor induced by the repeated administration of nicotine.

[Assessment of anti-tremorogenic drugs--nicotine-induced tail-tremor model]

The repeated administration of nicotine at small doses, which do not produce whole body tremor or convulsion, causes tremor only in the tail (tail-tremor) of rats. The tremor is accompanied by locomotor hyperactivity without rigidity and immobility of the whole body, suggesting that the nicotine-induced tail-tremor model is useful for studying the mechanism underlying tremor associated with movement. The tail-tremor induced by nicotine was suppressed by mecamylamine, a nicotinic antagonist, but not by atropine or scopolamine, muscalinic antagonists. Moreover, the tail-tremor was suppressed by the beta-blockers propranolol and pindolol, as well as the benzodiazepines diazepam and clonazepam. Tremor at rest is observed only in Parkinson's disease, which is improved with anti-muscalinic drugs. Essential tremor is one of the typical tremors connected with movement (postural and kinetic tremor) and is improved with beta-blocker. These findings and results suggest that nicotine-induced tail-tremor is useful for the study of essential tremor in animal models.

Role of central nicotinic and beta-adrenergic receptors in the onset and further development of tail-tremor induced by repeated nicotine administration to rats

The effects of nicotinic and beta-adrenergic receptor antagonists on tail-tremor induced by repeated nicotine administration were investigated in rats. The daily administration of nicotine (0.5 mg/kg/day, s.c.) for 8 days resulted in an augmentation of tail-tremor. However, repeated administration of dimethyl phenyl piperazinium iodide (1 mg/kg/day, s.c.) for 8 days did not cause tail-tremor. Mecamylamine (0.5 mg/kg, i.p), administered before the nicotine injection on each day, abolished the tail-tremor. After discontinuation of the mecamylamine treatment, nicotine injections caused tail-tremor augmentation. Propranolol (20 mg/kg, i.p.), administered before the nicotine on each day, suppressed the appearance of tail-tremor. After the discontinuation of propranolol treatment, the degree of tail-tremor induced by a single injection of nicotine on day 9 was much greater in the propranolol-treated group than in the saline-treated control group. Neither carteolol (20 mg/kg, i.p.) nor metoprolol (20 mg/kg, i.p.) treatment showed such effects. Intraspinal injection of 6-hydroxydopamine markedly enhanced the tail-tremor induced on the first day of nicotine injection. This effect became more intense on subsequent administration of nicotine. The enhanced tail-tremor following 6-hydroxydopamine treatment was abolished by mecamylamine (0.5 and 1 mg/kg, i.p.), and was suppressed by propranolol (5-20 mg/kg, s.c.) in a dose-dependent manner. These results suggest that central nicotinic receptors are essential for the onset and for the further development of tail-tremor induced by the repeated administration of nicotine, and that beta 2-adrenoceptors are associated with the tremor mechanism. Moreover, spinal noradrenergic mechanisms may be involved in the manifestation of this phenomenon.

[Behavioral changes induced by repeated administration of mazindol, an anorexiant, in rats]

Behavioral changes in locomotor activity and stereotyped behaviors induced by daily administration (for 7 days) of mazindol (5 and 10 mg/kg, po) were compared with those induced by methamphetamine (10 mg/kg) in rats. On day 1, mazindol increased locomotor activity, which was enhanced by daily administrations. Stereotyped behaviors were also induced by mazindol, which became more marked following daily administrations. Methamphetamine markedly increased stereotyped behavior rather than locomotor activity on day 1, and the effects were not enhanced by daily administrations. The increased locomotor activity and stereotyped behaviors caused by mazindol and methamphetamine were markedly reduced by the dopamine receptor antagonist pimozide (0.1-0.4 mg/kg, ip) in a dose-dependent manner. These results suggest that repeated mazindol administration enhances locomotor-stimulant and stereotypy-producing effects, which are mediated by the central dopaminergic system.

Potentiation of L-dopa-induced behavioral excitement by histamine H1-receptor antagonists in mice

Effects of histamine H1-receptor antagonists on L-dopa-induced behavioral excitement were examined in mice to confirm behaviorally the inhibition of dopamine uptake by these compounds. L-Dopa (100-300 mg/kg, s.c.) combined with pargyline hydrochloride (80 mg/kg, i.p.) caused a dose-dependent behavioral excitement. The marked excitement induced by L-dopa (300 mg/kg) plus pargyline was significantly inhibited by pimozide (0.1 - 1 mg/kg, s.c.), a selective dopamine antagonist. Tripelennamine (10 mg/kg, s.c.), d-chlorpheniramine (1 and 2 mg/kg, s.c.), homochlorcyclizine (2 and 5 mg/kg, s.c.), diphenhydramine (2 and 5 mg/kg, s.c.) and mepyramine (2 and 5 mg/kg, s.c.) each markedly enhanced the moderate behavioral excitement induced by L-dopa (150 mg/kg) plus pargyline. These findings are behavioral evidence for inhibition of dopamine uptake by H1 antagonists, which has been suggested by neurochemical studies.

Cerebrospinal fluid corticotropin-releasing hormone in neurodegenerative diseases: reduction in spinocerebellar degeneration

Levels of corticotropin-releasing hormone (CRH) in cerebrospinal fluid (CSF) were examined in patients with spinocerebellar degeneration (SCD) including olivopontocerebellar atrophy (OPCA), dentatorubropallidoluysian atrophy (DRPLA) and Friedreich's ataxia, Parkinson's disease (PD) and senile dementia of the Alzheimer type (SDAT), and normal aged subjects. CRH concentrations in CSF were significantly reduced in SCD compared to SDAT, PD and CSF and normal aged subjects. It is likely that degeneration not only of the cerebral cortex and the limbic system but also of the subcortical structures such as the brainstem and the cerebellum alters levels of CRH in CSF. Together with the recent anatomical and physiological evidence, the results suggest pathophysiological relevance of CRH for the cerebellar symptoms in SCD.

[Peripheral plasma corticotropin-releasing hormone (CRH) in an aged patient with fasting hypoglycemia associated with an insufficient secretion of insulin: an implication of plasma CRH in glucose metabolism]

We present a 66-year-old man with morning fasting hypoglycemia from an unknown cause associated with markedly suppressed levels of insulin. In this patient we examined the diurnal changes of plasma corticotropin-releasing hormone (CRH). ACTH, cortisol, glucose, insulin and body temperature, and the correlations among them. We also discussed an implication of plasma CRH in glucose metabolism by taking these findings together with results from previous studies on plasma CRH in diabetic or hypoglycemic animals and human beings. In this case, the stress induced by severe spontaneous hypoglycemia in the morning fasting state increased CRH in plasma compared to the euglycemia state and simultaneously activated the hypothalamic-pituitary-adrenal system as well as the sympathetic nervous system remarkably. The daily intravenous infusion of glucose brought the fasting hypoglycemia to normal and hypothermia to normothermia in the morning, and improved no or blunt responsiveness of insulin to glucose. On the 50th day of therapy, the i.v. infusion of glucose quickly produced moderate hyperglycemia and an increase in plasma insulin, and inhibited secretions of CRH, ACTH and cortisol. The source of plasma CRH remains obscure. However, the positive correlations of plasma CRH with both plasma ACTH and cortisol and several lines of evidence indicate that CRH in peripheral plasma is derived from both the hypothalamus and extrahypothalamic peripheral tissue and that during stressed conditions, in particular, the CRH increase in plasma is derived mainly from the paraventricular nucleus of the hypothalamus. The role of CRH not only in the systemic circulation but also in the endocrine pancreases for glucose metabolism remains to be clarified.

Characteristics of tail-tremor induced by nicotine in rats

To characterize the tail-tremor and locomotor hyperactivity induced by repeated nicotine administration, the effects of nicotinic, alpha-adrenergic and dopaminergic blockers were investigated in rats. Daily administration of nicotine (0.5 mg/kg, s.c.) induced tail-tremor from the 4th day, which became more marked in intensity by subsequent administration. Locomotor hyperactivity was also induced by nicotine, which was enhanced by daily administration. The tail-tremor and locomotor hyperactivity induced by repeated nicotine administration were inhibited by mecamylamine (0.1-1 mg/kg, i.p.) but not by hexamethonium (0.5 and 1 mg/kg, i.p.). Clonidine (0.02 and 0.04 mg/kg, i.p.) and prazosin (0.5 and 1 mg/kg, i.p.) reduced tail-tremor more markedly than hyperactivity. However, haloperidol (0.05-0.2 mg/kg, i.p.) and chlorpromazine (1-5 mg/kg, i.p.) reduced hyperactivity more markedly than tail-tremor. These results suggest that nicotine-induced tail-tremor and hyperactivity are due to an increased susceptibility of central nicotinic receptors of nicotine followed by catecholaminergic mechanisms, and that tail-tremor may be more associated with the noradrenergic system than the dopaminergic system.

Effect of beta-adrenergic receptor antagonists on nicotine-induced tail-tremor in rats

The effects of various beta-adrenergic receptor antagonists on nicotine-induced tail-tremor were investigated in rats. Atenolol (5 and 10 mg/kg, IP), arotinolol (5 and 10 mg/kg, IP), and carteolol (5 and 10 mg/kg, IP), hydrophilic beta-adrenergic receptor antagonists, did not affect the tail-tremor induced by nicotine given at a dose of 0.5 mg/kg SC. However, propranolol (5-20 mg/kg, IP) and pindolol (5-20 mg/kg, IP), nonselective and lipophilic beta-adrenergic receptor antagonists, did suppress the tail-tremor dose dependently. In contrast, metoprolol (5-20 mg/kg, IP), lipophilic and beta 1-selective adrenergic receptor antagonists, did not show such an effect. These results suggest that nicotine-induced tail-tremors may be mediated through central beta 2-adrenergic receptors as an appearance and developmental mechanism.

Chronic nicotine treatment potentiates behavioral responses to dopaminergic drugs in rats

In the present study, the behavioral effects of apomorphine, methamphetamine, and haloperidol were examined in nicotine-treated rats. All animals were SC administered nicotine at a dose of 0.5 mg/kg or saline once daily for 14 days. Hyperlocomotion induced by apomorphine (0.2 mg/kg, IP) and methamphetamine (1.0 mg/kg, IP) was greater in nicotine-treated rats than in control rats. Stereotyped behaviors induced by apomorphine (1.0 mg/kg, IP) and methamphetamine (5.0 mg/kg, IP) were also potentiated in nicotine-treated rats. However, the incidence of catalepsy induced by haloperidol (0.25-1.5 mg/kg, IP) was slightly lower in nicotine-treated rats. These results suggest that chronic nicotine treatment may increase the susceptibility of the dopaminergic system to dopaminergic drugs.

Possible explanations for the antagonism by nicotine against reserpine-induced depletion of monoamines in mouse brain

The inhibitory effect of nicotine pretreatment on reserpine-induced depletion of monoamines in mouse brain was investigated. The depletion of brain monoamines by 24 h after intraperitoneal injection of reserpine (2 mg/kg) was dose-dependently inhibited by nicotine (0.3-10 mg/kg, s.c.) pretreatment 20 min before reserpine injection. This effect of nicotine was more marked on dopamine depletion than on noradrenaline or 5-hydroxytryptamine depletion. The nicotine pretreatment also inhibited the reserpine-induced hypothermia and decrease in the locomotor activity. When reserpine (2 mg/kg) was injected intraperitoneally, the inhibitory effect of nicotine (3 mg/kg, s.c.) on the reserpine-induced depletion of brain monoamines and heart noradrenaline was not antagonized by hexamethonium (8 mg/kg, s.c.) but rather potentiated by mecamylamine (2 mg/kg, s.c.). However, when reserpine (0.5 mg/kg) was injected intravenously, pretreatment with nicotine (3 mg/kg, s.c.) inhibited the reserpine-induced dopamine depletion only, and this effect of nicotine was completely blocked by mecamylamine but not by hexamethonium. These results suggest that inhibitory effect of nicotine on the intraperitoneal reserpine-induced depletion of brain monoamines is due to an inhibition of absorption of reserpine, and that central nicotinic action is also involved in the antagonism by nicotine of reserpine-induced dopamine depletion.

[Cerebrospinal fluid and plasma corticotropin-releasing hormone (CRH) in dentatorubropallidoluysian atrophy (DRPLA)--study in two cases of hereditary DRPLA]

The levels of corticotropin-releasing hormone (CRH) in cerebrospinal fluid (CSF) and plasma were examined in two cases of hereditary dentatorubropallidoluysian atrophy (DRPLA). Both patients were female and showed cerebellar ataxia, choreic movement and subcortical dementia. The onset ages of the first and second patients were 30 and 47 years, respectively. The first patient did not have the cerebral white matter damage (CWD). The second patient of late onset was associated with marked and diffuse CWD which was shown as high signal intensity by T2-weighted image on MRI. Regardless of accompaniment with CWD, the radioimmunoassay studies of CSF and plasma CRH revealed that both patients had markedly reduced levels of CRH in CSF and plasma. Together with the recent anatomic evidence on the distribution of CRH neurons and receptors in the central nervous system, the present results suggest that degeneration of the subcortical structures including the basal nuclei, the brain stem and the cerebellum involves degeneration and/or dysfunction of the CRH neuronal system which, presumably, are related to those of some other neurotransmitter systems, and that the reduced activity of the CRH system plays a pathophysiological role in such diseases as DRPLA with degeneration of the subcortical nuclei and the cerebellum.

Cerebrospinal fluid corticotropin-releasing hormone and ACTH, and peripherally circulating choline-containing phospholipid in senile dementia

Cerebrospinal fluid (CSF) levels of corticotropin-releasing hormone (CRH) and ACTH, plasma levels of ACTH and cortisol, and serum levels of phospholipid and its fractions were determined in samples taken simultaneously from patients with senile dementia of the Alzheimer type (SDAT), multi-infarct dementia (MID) or dementia following a cerebrovascular accident (CVD), and the borderline-to-normal control subjects. CRH levels in CSF were significantly reduced in patients with SDAT and CVD but not with MID compared to the borderline-to-normal controls. ACTH levels in CSF were significantly reduced in SDAT compared to MID. The levels of circulating lecithin (phosphatidyl-choline) were depressed in a similar fashion to the levels of CRH in CSF in the SDAT patients and the group of severe dementia. Dementia and its severity did not affect the morning plasma levels of ACTH and cortisol. CSF CRH was positively correlated with CSF ACTH, while CSF ACTH was negatively correlated with plasma cortisol. No significant correlations were found between serum lecithin and CSF CRH or ACTH. These findings suggest that: 1) abnormalities in the extrahypothalamic CRH system play a role in the pathophysiology of senile dementia, which may not be specific to SDAT; 2) the CRH system and the ACTH system correlate with each other within the brain; 3) CSF ACTH is subject to the feedback inhibition by circulating cortisol; and 4) in the SDAT patients and the severe dementia group CSF CRH and serum lecithin are reduced probably via independent mechanisms.

Effect of long-term cigarette smoke exposure on locomotor activity and brain monoamine levels in rats

Rats were chronically exposed to cigarette smoke for 20 min twice daily using a smoking machine. On days 1, 4, and 14, locomotor activity and rearing were measured for 15 min in an open-field apparatus. On day 1, exposure to cigarette smoke increased locomotor activity and rearing in the latter half of the observation period. This effect became more pronounced on days 4 and 14. Chronic cigarette smoke exposures for 21 days significantly decreased the norepinephrine levels in the hypothalamus, thalamus, and pons-medulla, but not the levels of dopamine, 5-hydroxytryptamine, or their metabolites. These results suggest that repeated cigarette smoke exposure increasingly stimulates locomotor activity and rearing and affects norepinephrine metabolism, especially in the brainstem.

Tail-tremor induced by exposure to cigarette smoke in rats

Tremors appearing only in the tail (tail-tremor) induced by cigarette smoke and subcutaneous nicotine were investigated using a smoking machine and Wistar rats. Daily exposure (twice a day) to smokes of two commercial cigarettes (Mild-Seven Select for the first 7 days and Long-Peace for the next 6 days) caused the tail-tremor to appear even if it was slight. A single subcutaneous nicotine (0.5 mg/kg) administration to rats exposed to the cigarette smokes for 13 days markedly caused the tail-tremor. On the other hand, daily subcutaneous injection of nicotine (0.5 mg/kg/day) also caused the tail-tremor to appear beginning on the 4th day and the incidence of tremor increased to 100% by the 12th day. These results indicate that tail-tremor can be caused not only by daily subcutaneous administration of nicotine but also by daily exposure to cigarette smoke.

Effect of cigarette smoking on theophylline pharmacokinetics in rats

The effect of acute cigarette smoke inhalation on the plasma levels of theophylline administered orally and parenterally to rats has been studied. The animals were exposed to smoke containing low- or high-nicotine/tar concentration for 10 min immediately after oral, intraperitoneal (i.p.) or intravenous (i.v.) administration of theophylline. The plasma levels of theophylline when administered orally (20 mg kg-1) were lower in the two cigarette smoke-inhaling groups than in the non-smoking restrained control group, with the lowest values in the high-nicotine/tar group. The plasma levels (8 and 12 h after administration) in the high-nicotine/tar group when theophylline was administered i.p. (10 mg kg-1), were also slightly lower than in the non-smoking restrained control group but this was not significant. When theophylline was administered i.v. (5 mg kg-1), there was no difference between the high-nicotine/tar group and the non-smoking restrained control group. These data indicate that cigarette smoke inhalation causes suppression or delay of theophylline absorption from the gastrointestinal tract.

Hyperkinesia, plasma corticotropin releasing hormone and ACTH in senile dementia

Senile dementia of the Alzheimer type (SDAT), in contrast to multi-infarct dementia (MID) was associated with delirium and marked increases in the number of walking steps taken during both the day and night. In SDAT patients, plasma ACTH levels in the afternoon and evening were higher but plasma corticotropin releasing hormone (CRH) levels in the evening were lower than in the MID patients. A positive correlation between ACTH levels and walking steps and a negative correlation between plasma levels of CRH and ACTH were found. These results suggest relevance of hyper-kinetic delirium to disruption of diurnal rhythm of the pituitary-adrenal axis, and a possible mechanism of the short feedback suppression of CRH release by increased circulating ACTH.

Cerebrospinal fluid and plasma corticotropin-releasing hormone in senile dementia

Cerebrospinal fluid (CSF) levels of corticotropin-releasing hormone (CRH) and ACTH, and plasma levels of CRH, ACTH and cortisol were determined in samples taken simultaneously from 28 patients with dementia including senile dementia of the Alzheimer type (SDAT), multi-infarct dementia (MID), dementia following a cerebrovascular accident (CVD), and the borderline-to-normal state. CRH levels in CSF were significantly reduced in patients with SDAT and CVD, but not in those with MID, as compared with the borderline cases. ACTH levels in CSF were significantly reduced in the patients with SDAT compared to those with MID. Reduced CRH levels in CSF were found in the patients who showed severe dementia and poor activities of daily living (ADL). Plasma levels of CRH, ACTH and cortisol were normal and were not significantly different among the four groups of patients. CRH levels in CSF were positively correlated with ACTH levels in CSF, but not with the levels of plasma CRH, ACTH or cortisol. Plasma CRH levels were positively correlated with plasma ACTH levels. These results suggest that: 1) abnormalities in the extrahypothalamic CRH system play a role in the pathophysiology of senile dementia, which may not be specific to SDAT; 2) CSF CRH is correlated with the severity of dementia and ADL; 3) the levels of CRH in CSF and plasma are independent, and 4) the plasma CRH reflects, at least in part, the activity of the hypothalamic CRH regulating the secretion of pituitary ACTH.

Behavioral effects of HR-592, a new derivative of indole

Effects of HR-592 on various behaviors were investigated in rats and mice. 1) HR-592 at doses of 10-100 mg/kg, p.o., and chlorpromazine at doses of 2.5-20 mg/kg, p.o., suppressed dose-dependently spontaneous activities of mice. 2) In the mice treated with HR-592, 10 and 30 mg/kg, p.o., and with chlorpromazine, 1.25-5 mg/kg, p.o., the durations of loss of the righting reflex induced by thiopental-Na were extended in a dose-dependent manner. 3) In the mice and rats when HR-592 was administered at doses of 3-100 mg/kg, p.o., catalepsy was induced in a dose-dependent manner. 4) The incidence of catalepsy induced by haloperidol in mice was reduced dose-dependently after HR-592 administration (10-100 mg/kg, p.o.). 5) Dose-dependent suppressions of the slant of screen at which the mice slipped down were observed by HR-592 at 3-100 mg/kg, p.o., and chlorpromazine at 5-20 mg/kg, p.o. 6) The rotarod performance in mice was suppressed dose-dependently by HR-592, 3-100 mg/kg, p.o., and chlorpromazine, 5-20 mg/kg, p.o. 7) HR-592 at doses of 0.3-3 mg/kg, i.p., suppressed dose-dependently the turning behavior induced by methamphetamine in unilateral substantia nigra-lesioned rats. From these results and our previous data, it is considered that HR-592 has pharmacological properties as a major tranquilizer, although its behavioral effect is slightly weaker than that of chlorpromazine. Furthermore, these results imply that HR-592 has anti-cataleptogenic activity and might thereby alleviate the adverse effect of neuroleptics such as haloperidol.

Nicotine-induced tail-tremor and drug effects

Tail-tremor induced by repeated and daily administration (0.5 mg/kg SC x 6 times/day) of nicotine as well as effects of various drugs on this response were investigated in Wistar strain male rats. Daily administration of nicotine in doses of 0.5 mg/kg SC caused tail-tremors to appear beginning on the 3rd day. Tail-tremor induced by the first injection of each day gradually increased with the daily injections, however, the heightened effect of this first injection at the beginning of each day decreased during the day upon repeated administration of 6 times/day at 2-hr intervals. Basically, tail-tremor appeared about 5 min after SC administration of nicotine and reached a peak approximately 7-9 min after injection, declining to zero afterwards. Different drugs showed various effects on this response. While mecamylamine (0.5 and 1.0 mg/kg IP) abolished nicotine-induced tail-tremor, arecoline (0.5 and 1.0 mg/kg IP), atropine (2.5 and 5.0 mg/kg IP), scopolamine (1.0 and 2.0 mg/kg IP) and hexamethonium (0.5 and 1.0 mg/kg IP) showed no such effects. Furthermore, physostigmine (0.1 mg/kg IP) actually potentiated this action. These results suggest that tail-tremor induced by nicotine may be mediated through central nicotine receptor system.