Effects of electroacupuncture on the ventral tegmental area- nucleus accumbens dopamine pathway in rats with chronic sleep deprivation

BACKGROUND

Insomnia is a well-recognized clinical sleep disorder in the adult population. It has been established that acupuncture has a clinical effects in the treatment of insomnia; however, research on the underlying neural circuits involved in these effects is limited.

METHODS

The modified multiple platform method (MMPM) was used to establish a rat model of chronic sleep deprivation (CSD). Forty rats were randomly divided into a control (Con) group, (untreated) CSD group, electroacupuncture-treated CSD group (CSD + EA) and estazolam-treated CSD group (CSD + Estazolam group) with n = 10 per group. In the CSD + EA group, EA was delivered at Yintang and unilateral HT7 (left and right treated every other day) with continuous waves (2 Hz frequency) for 30 min/day over 7 consecutive days. In the CSD + Estazolam groups, estazolam was administered by oral gavage (0.1 mg/kg) for 7 consecutive days. The open field test (OFT) was used to observe behavioral changes. Immunofluorescence assays and enzyme-linked immunosorbent assay (ELISA) were used to observe the effects of EA on the ventral tegmental area (VTA)-nucleus accumbens (NAc) dopamine (DA) pathway. We also assessed the effects of EA on the expression of dopamine D1 receptor (D1R) and dopamine D2 receptor (D2R) in the NAc, which are the downstream targets of the VTA-NAc DA pathway.

RESULTS

After CSD was established by MMPM, rats exhibited increased autonomous activity and increased excitability of the VTA-NAc DA pathway, with increased VTA and NAc DA content, increased D1R expression and decreased D2R expression in the NAc. EA appeared to reduce the autonomous ability of CSD rats, leading to lower DA content in the VTA and NAc, reduced expression of D1R in the NAc and increased expression of D2R. Most importantly, EA produced effects similar to estazolam with respect to the general condition of rats with CSD and regulation of the VTA-NAc DA pathway.

CONCLUSIONS

The therapeutic effect of EA in chronic insomnia may be mediated by reduced excitability of the VTA-NAc DA pathway, with lower DA content in the VTA and NAc, downregulated expression of D1R in the NAc and increased expression of D2R.

Determination of hypnotic benzodiazepines (alprazolam, estazolam, and midazolam) and their metabolites in rat hair and plasma by reversed-phase liquid-chromatography with electrospray ionization mass spectrometry

Sensitive determination of benzodiazepines i.e., alprazolam (ALP), estazolam (EST), and midazolam (MDZ), and their metabolites, was carried out by reversed-phase liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC-ESI-MS). The chromatography separations were achieved using a semi-micro HPLC column (3 microm particle size; 100 x 2.0 mm, i.d.) with acetonitrile-water containing 1% acetic acid as eluent. The mass spectrometer was operated in selected-ion monitoring mode at protonated-molecular ions [M+H](+) of parent drugs and the metabolites. The proposed procedure was applied to the determination in hair shaft of Dark Agouti rats after intraperitoneal (i.p.) administration of benzodiazepines twice a day for 5 days. Various metabolites together with parent drugs were identified in the hair shaft, 1-hydroxyalprazolam (1-HA) and 4-hydroxyalprazolam (4-HA) from ALP administration; 8-chloro-6-phenyl-4H-[1,2,4]triazolo[4,3-a][1,4]benzodiazepine-4-one (K-EST) from EST administration; 1-hydroxymidazolam (1-HM) and 4-hydroxymidazolam (4-HM) from MDZ administration. A few unknown metabolites were also detected in the hair samples. These structures were elucidated with acetylation using acetic anhydride and pyridine. The time course studies of parent drugs and the metabolites in both hair root and plasma were also carried out after single i.p. administration of benzodiazepines. The results suggested that the concentrations of parent drugs and the metabolites in the hair samples were mainly dependent upon those in the plasma.

Benzodiazepine receptor binding of triazolobenzodiazepines in vivo: increased receptor number with low-dose alprazolam

Triazolobenzodiazepines are in clinical use as hypnotics and anxiolytics. We analyzed in vivo receptor binding and brain concentrations of alprazolam, triazolam, and estazolam. Drug concentrations measured in the cerebral cortex 1 h after administration were directly proportional to dose for all three compounds. In vivo receptor binding, as defined by the specific uptake of [3H]Ro15-1788, decreased with increasing doses of estazolam and triazolam, a finding indicating dose-related increases in receptor occupancy due to these compounds. Triazolam was substantially more potent, with an IC50 value of 16 ng/g, compared with 117 ng/g for estazolam. At higher doses of alprazolam (greater than 0.2 mg/kg), receptor binding by [3H]Ro15-1788, likewise decreased with increasing dose of the former drug. However, at lower doses of alprazolam (0.02-0.05 mg/kg), which resulted in cortex concentrations of 2-7 ng/g, receptor binding was increased above control values in cortex, hypothalamus, and hippocampus but not in several other brain regions. Binding returned to control values at doses of greater than or equal to 0.01 mg/kg. Similar results were obtained in time course studies. At 8 and 10 h after a dose of 1 mg/kg i.p., corresponding to cortex concentrations of 2.7-7 ng/g, receptor binding was increased compared with controls. Similarly, at 1, 2, and 3 h after a single dose of 0.05 mg/kg, corresponding to cortex concentrations of 3.7-5.8 ng/g, receptor binding was also increased. The apparent affinity of benzodiazepine receptors for clonazepam in mice receiving alprazolam (0.05 mg/kg) was unchanged from that in untreated control mice, an observation suggesting that low doses of alprazolam increased receptor number.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative efficacy of estazolam, flurazepam, and placebo in outpatients with insomnia

The efficacy and safety of estazolam, an investigational triazolobenzodiazepine, and flurazepam were compared in 65 insomniac outpatients. Patients completed sleep questionnaires each morning. Global evaluations demonstrated that both treatments were significantly superior to placebo. However, estazolam was preferred over flurazepam in a global rating that reflected how well rested and refreshed the subjects felt on arising. Improvement in complaints of difficulty in going to sleep showed only a trend toward significance favoring estazolam and flurazepam over placebo. Residual daytime drowsiness and fatigue accounted for approximately 70% of all side effects with both active treatments. Significantly more side effects occurred with flurazepam than with estazolam. Flurazepam-treated patients had a significantly more severe rating of adverse reactions than did placebo-treated patients.

Metabolism of 14C-estazolam in dogs and humans

14C-Estazolam (2 mg) administered orally to dogs and human subjects was rapidly and completely absorbed with peak plasma levels occurring within one hour. In humans, plasma levels peaked at 103 +/- 18 ng/ml and declined monoexponentially with a half-life of 14 h. The mean concn. of estazolam in dog plasma at 0.5 h was 186 ng/ml. Six metabolites were found in dog plasma at 0.5 and 8 h, whereas only two metabolites were detected in human plasma up to 18 h. Metabolites common to both species were 1-oxo-estazolam (I) and 4-hydroxy-estazolam (IV). Major metabolites in dog and human plasma were free and conjugated 4-hydroxy-estazolam; the concn. were higher in dogs. After five days, 79% and 87% of the administered radioactivity was excreted in dog and human urine, respectively. Faecal excretion accounted for 19% of the dose in dog and 4% in man. Eleven metabolites were found in the 0-72 h urine of dogs and humans; less than 4% dose was excreted unchanged. Four metabolites were identified as: 1-oxo-estazolam (I), 4'-hydroxy-estazolam (II), 4-hydroxy-estazolam (IV) and the benzophenone (VII), as free metabolites and glucuronides. The major metabolite in dog urine was 4-hydroxy-estazolam (20% of the dose), while the predominant metabolite in human urine (17%) has not been identified, but is likely to be a metabolite of 4-hydroxy-estazolam. The metabolism of estazolam is similar in dog and man.

Kinetic and pharmacological studies on estazolam in mice and man

After i.v. and oral doses of estazolam (5 mg/kg) to mice, the drug was rapidly cleared with a beta half-life (t1/2 beta) of 0.7 h. The active metabolite, 1-oxo-estazolam, was present in traces in mouse plasma and brain. Its elimination t1/2 (beta), determined after i.v. injection of 1-oxo-estazolam (5 mg/kg) to mice, was similar to that of the parent drug in both plasma and brain. After a single oral dose of estazolam (4 mg) to four human volunteers the drug was rapidly absorbed and reached maximum plasma concentrations in one to three hours. Elimination t1/2 of estazolam in humans was 19 h. The metabolite was undetectable in human plasma after either single or multiple doses of estazolam. These results, together with the finding that 1-oxo-estazolam was less effective than estazolam, in terms of ED50 and brain concentrations necessary to antagonize leptazol convulsions and disrupt rota-rod performance in mice, indicate that the metabolite does not contribute significantly to the pharmacological effects of its parent drug.

Single- and multiple-dose kinetics of estazolam, a triazolo benzodiazepine

The pharmacokinetic properties of estazolam, a triazolo benzodiazepine hypnotic agent, were assessed in a series of healthy volunteers following single and multiple doses. After single oral doses of 2--16 mg, peak plasma concentrations were reached within 6 h. Values of elimination half-life ranged from 8.3--31.2 h (mean 17.0 h) and did not vary significantly with dose. During 3 weeks of therapy, steady-state plasma concentrations increased approximately in proportion to increasing doses. and accumulation was essentially complete within 3 days of each dose change. The mean observed accumulation ratio was 1.84, which was slightly larger than the predicted ratio of 1.53. Exposure to multiple-dose estazolam therapy had no significant influence on the kinetics of a single dose of antipyrine, suggesting that estazolam neither stimulates nor inhibits enzyme activity in humans. Thus the accumulation and elimination kinetics of estazolam can be classified as intermediate to those of the short-acting (such as oxazepam) and the long-acting (such as diazepam) benzodiazepine derivatives.