Automatic quantification of withdrawal from 5-day diazepam in rats: ultrasonic distress vocalizations and hyperreflexia to acoustic startle stimuli

The purpose of the present work was to develop an objective and precise method to quantify withdrawal responses from anxiolytics relying on ethologically valid responses. Behavioral effects of diazepam withdrawal in rats are automatically measured that appear to correspond to clinically relevant disturbances in affective and sensory-motor functions. Ultrasonic vocalizations and startle reflexes in response to acoustic stimuli were measured as indices of withdrawal 24 h after 5 days of 2.5, 5 or 10 mg/kg diazepam, b.i.d., IP in male Long-Evans rats. About 60% of male rats emit 22–26 kHz ultrasonic calls when exposed to acoustic startle stimuli (18 presentations, 9 at 105 dB and 9 at 115 dB, each 30 s apart on average). Diazepam-withdrawn rats exhibited startle responses with larger maximal and average amplitude and emitted more frequent 22–26 kHz ultrasonic vocalizations than vehicle-treated control animals. The magnitude of the withdrawal changes in ultrasonic calls and in startle reflex amplitude increased significantly already at the low 2.5 mg/kg diazepam dose in spite of considerable individual variability. The increased ultrasound rates during diazepam withdrawal contrast with the suppressive effects of acutely administered diazepam in drug-naive rats. The current methodology offers the opportunity to more adequately characterize withdrawal from anxiolytic substances in a quantitative, objective and automated manner.     

Enhanced ultrasonic vocalization and Fos protein expression following ethanol withdrawal: effects of flumazenil

RATIONALE: The acquisition of a caffeine conditioned flavour preference depends on the caffeine deprivation status of subjects during conditioning. It is not known if the expression of an established flavour preference is also state-dependent. OBJECTIVES: To determine if the expression of a flavour preference conditioned by caffeine is dependent on the level of deprivation at the time of testing. METHODS: In a double-blind placebo controlled study, 44 subjects were given 4 days exposure to a novel flavoured drink following overnight abstinence from caffeine. Half the subjects received caffeine (100 mg) in the drink, while the remainder had placebo (maltodextrin, 100 mg). Subjects rated the pleasantness of the drink each time. On a fifth (test) day, the subjects were given additional caffeine (100 mg) or placebo 2 h before consuming and rating the pleasantness of the drink. RESULTS: Pleasantness ratings for the novel drink increased over the 4 conditioning days in subjects receiving caffeine, but decreased in those given placebo. On day 5, subjects who were trained and tested in the same caffeine deprivation state expressed pleasantness ratings similar to those for the final training day. In contrast, subjects who were trained and tested in different states expressed pleasantness ratings that were significantly different from those of the final training day. CONCLUSIONS: These results suggest that the expression of caffeine conditioned flavour preferences are acutely sensitive to current motivational state, and a number of possible explanations are discussed.     

Withdrawal from oral cocaine in rats: ultrasonic vocalizations and tactile startle

While anxiety appears to characterize humans who administer high doses of cocaine or experience withdrawal from cocaine, it is difficult to capture this aspect of cocaine effects in animals. The present study investigated if acute or protracted withdrawal from prolonged low-dose cocaine that is self-administered via the oral route could be detected in tactile startle and vocal distress responses of rats. Adult, male Long-Evans rats had access to cocaine solution (0.1 mg/ml) either for 24 or 4 h/day using the two-bottle choice technique. The amount of solution consumed from each bottle was measured daily for 30 or 60 days. On days 1, 3, 7, 14, 21, 28 of withdrawal, startle and ultrasonic vocal responses (USV, 15–35 kHz) were measured in response to 18 airpuff stimuli (20 psi). Rats drank an average of 5–20 mg/kg per day of the cocaine solution. On average, about half of the daily liquid was consumed from the cocaine solution-containing bottle. USVs were emitted at significantly increased rates on day 3 of withdrawal from 30 or 60 days of cocaine drinking. Startle reactions were slightly, but non-significantly increased on day 1 of withdrawal. Comparable to withdrawal from ethanol, morphine, and diazepam treatments, withdrawal from oral self-administration of low to moderate doses of cocaine increases the rate of ultrasonic vocalizations while increasing minimally the amplitude of startle responses to low-intensity tactile stimuli. Nevertheless, no correlation between the total amount of cocaine self-administered or the duration of treatment with the intensity of the withdrawal manifestations could be detected.     

Precipitated diazepam withdrawal in baboons: effects of dose and duration of diazepam exposure

Baboons were exposed to diazepam via continuous injection at doses of 0.125-20.0 mg/kg per day intragastrically (i.g.) for 7 days or to 20 mg/kg per day, i.g. for 1 h or 1 to 35 days. After diazepam administration, Ro 15-1788, a benzodiazepine antagonist was given (5.0 mg/kg i.m.) and precipitated benzodiazepine withdrawal was evaluated by scoring individual signs. The severity of the withdrawal, as indicated by the number of the different signs as well as by frequency of individual signs, increased as the dose and duration of diazepam exposure were increased. Consistent elevations in diazepam withdrawal signs were evident after a dose as low as 0.25 mg/kg per day for 7 days and after administration of 20 mg/kg per day for as short as 3-7 days. Data also suggested that history of previous benzodiazepine exposure sensitized animals to subsequent development of physical dependence. Overall, this study suggests that benzodiazepines produce meaningful functional changes in the central nervous system after exposure to relatively low doses and after relatively short durations of exposure.     

Cocaine: Excitatory effects on sensorimotor reactivity measured with acoustic startle

Cocaine (2.5–10 mg/kg) caused a dose-related increase in the amplitude of the acoustic startle reflex in rats. In contrast, procaine (5–40 mg/kg) caused a dose-related decrease in startle, indicating that the effects of cocaine could not be ascribed to its local anesthetic effects. Cocaine's excitatory effects were blocked by pretreatment with haloperidol (0.5 mg/kg) but not by cyproheptadine or prazosin. The excitatory effects of cocaine (10 mg/kg) were markedly attenuated by pretreatment with reserpine (5 mg/kg 24 and 18 h earlier) but not by -methyl-p-tyrosine (100 mg/kg 1 h earlier). In contrast, comparably sized excitatory effects of d-amphetamine were blocked by -methyl-p-tyrosine and greatly enhanced by pretreatment with reserpine. Neither pretreatment blocked excitatory effects of apomorphine on startle. The data indicate that cocaine increases startle by acting through reserpine-sensitive pools of dopamine and provide further support for the conclusion that acoustic startle is enhanced by activation of dopamine receptors.     

Excitatory effects of the vasodilator hydralazine on acoustic startle in the rat

Several drugs that functionally depress noradrenergic transmission depress acoustic startle amplitude (e.g., clonidine, phenoxybenzamine). Since these agents also depress blood pressure, the current study was designed to investigate the effects of hypotension per se (in the absence of decrease noradrenergic transmission) on the acoustic startle response. The vasodilator hydralazine was chosen because it produces marked hypotension in conscious rats, yet results in a compensatory increase in noradrenergic transmission (sympathetic rebound), rather than a decrease, as is seen with many other hypotensive agents. Hydralazine (0.3–20 mg/kg, IP) produced a marked and long-lasting increase in startle amplitude, compared to saline-treated controls. In a similar group of subjects, IP administration of 2.5 mg/kg hydralazine decreased mean arterial blood pressure by about 50% in conscious rats. Since, at the doses and treatment times employed in the present study, hydralazine decreases blood pressure but not startle amplitude, these data suggest that there is no relationship between changes in blood pressure and changes in startle amplitude across all drugs. Moreover, since hydralazine-induced hupotension results in an increase in noradrenergic transmission (sympathetic rebound), these data are consistent with the hypothesis that increases in central noradrenergic transmission increase acoustic startle amplitude. Lastly, since the most prominent direct action of hydralazine occurs in the periphery, hydralazine may alter startle through central actions that are triggered in the periphery.     

Harmaline effects on the sensory-motor reactivity: Modifications of the acoustic startle pattern

The effects of harmaline, an indoleamine and a MAOI, were tested on the acoustic stratle pattern. EMG measures of the startle reflex, the pinna reflex as well as the characteristic of the vertex evoked responses to brief intense tone burst (60 msec, 110 dB,8000 Hz) were simultaneously studied in 4 alert guinea-pigs. The basic experimental design was a 4 latin square, with the treatments being given at 2 day intervals. The four harmaline-HCI treatments were isotonic saline, 0.25 5.0 and 10.0 mg/kg. Compared with saline baselines, all the doses resulted, throughout the 60 min session, in overall high significant depressions of the startle reflex, the pinna reflex and the initial wave of the acoustic evoked potential at the vertex. In contrast, harmaline had little or no influence on amplitude and latency of the late wave of the vertex response. The effects of harmaline on the general behavior of the guinea-pig are also reported. These results may support an involvement of serotonergic systems in the modulation of the sensory-motor reactivity at the brainstem level. Nevertheless, the probab;y more complex cortical processes involved in startle responsivity do not appear univocally affected by the indoleamine drugs such as harmaline.     

Ultrasonic communication in rats: Effects of morphine and naloxone on vocal and behavioral responses to playback of 50-kHz vocalizations

Rats emit ultrasonic vocalizations and it was hypothesized that these vocalizations have an important role in intra-specific communication. Recently, we demonstrated that playback of 50-kHz ultrasonic vocalizations can induce social approach, indicating that 50-kHz calls can serve to (re)establish or to maintain social contact. It is known that endogenous opioids are implicated in the regulation of social behavior, particularly in rough and tumble play. Here, we tested whether administration of opioid ligands can affect social approach in response to playback of 50-kHz calls in juvenile and adult rats. Rats were either treated with 1 mg/kg naloxone, 1 mg/kg morphine, or with saline vehicle. Administration of opioid ligands affected social approach at both ages. Specifically, in juvenile and adult rats, social approach displayed in response to playback of 50-kHz calls was reduced in case of naloxone treatment, but enhanced with morphine. Furthermore, juvenile rats treated with saline or morphine emitted a substantial amount of ultrasonic vocalizations in response to the playback of 50-kHz calls. Such ultrasonic calling was not seen in naloxone treated rats. Importantly, these drug-dependent differences were stimulus-specific, i.e. seen only in response to playback of 50-kHz calls and not in response to playback of background noise. The present finding that opioid ligands can affect social approach and ultrasonic vocalizations induced by playback of 50-kHz calls, indicates that an important feature of social interaction in rats, namely ultrasonic communication, is at least partially regulated by endogenous opioids.     

A comparison of the effects of RO15,1788 and chlordiazepoxide on hot-plate latencies,acoustic startle,and locomotor activity

RO15,1788, (a selective benzodiazepine antagonist) and chlordiazepoxide (an anxiolytic 1,4-benzodiazepine) produced time-dependent and dose-dependent effects on various indices of sensory-motor function. RO15,1788 increased hot-plate latencies at doses (10–60 mg/kg) that had no effect on locomotor activity. Furthermore, the increased hot-plate latencies were observed 15, but not 30, 60, or 120 min after injection of 10 mg/kg RO15,1788. In contrast, chlordiazepoxide (2.5, 5.0, 10.0, 20.0 mg/kg) produced a dose-dependent increase in response times on the hot-plate, which appeared to be related to the depressant effects of this compound on motor activity. CDZ significantly decreased overall motor activity in a dose-related manner, with the two lower doses decreasing activity approximately 75% relative to controls. RO15,1788 (10 mg/kg) also decreased the magnitude of the acoustic startle response measured over 20 stimulus presentations. The startle response was significantly depressed during each of four 5-trial blocks. The magnitude of both the first and the largest response recorded was also decreased by this compound. Chlordiazepoxide (2.5 mg/kg) significantly decreased the magnitude of the startle response only during the first block of five stimulus presentations. These results are discussed in terms of the involvement of benzodiazepine-mediated processes in the modulation of sensory function and behavioral reactivity to biologically-relevant information.     

Evaluation of the dependence potential of the selective 5-H1A agonist ipsapirone in rats and of its effects on benzodiazepine withdrawal

Two initial studies investigated: i) the effects of withdrawal from ipsapirone [a putative non-benzodiazepine (BZ) anxiolytic] and chlordiazepoxide (CDP); and ii) effects of ipsapirone in animals withdrawn from CDP. Rats were injected b.i.d. for 21 days with saline, ipsapirone or CDP at doses up to 40 mg/kg/injection. Subsequently, controls received the treatment administered previously, other subjects received saline during withdrawal from ipsapirone or CDP. Further subjects received ipsapirone (3, 10 or 30 mg/kg b.i.d.) during CDP withdrawal. Withdrawal indices recorded were body weight and food intake. Withdrawal signs were absent after ipsapirone treatment but present after CDP treatment, when food intake and bodyweight measures fell and then recovered. At the high dose of 30 mg/kg (b.i.d.) ipsapirone potentiated CDP withdrawal signs. Potentiation of withdrawal wasnot seen in animals treated with ipsapirone at lower doses (3 and 10 mg/kg, b.i.d.). In a subsequent study we found that ipsapirone conditioned a taste aversion, a possible index of drug-induced malaise, at doses as low as 7.5 mg/kg. Therefore a possible explanation for the potentiation of BZ withdrawal in subjects treated with high doses of ipsapirone was that drug-induced malaise reduced food intake and body weight, rather than ipsapirone causing true potentiation of BZ withdrawal. However, in a further study we showed that the ipsapirone treatment regime which potentiated BZ withdrawal didnot significantly reduce food intake or body weight, suggesting that high doses of ipsapirone potentiate BZ withdrawal by a mechanism that does not simply involve malaise. The most plausible account of the observed potentiation of withdrawal by ipsapirone involves actions of the ipsapirone metabolite (1-(2-pyrimidinyl)-piperazine) on alpha₂-adrenoceptors, which are known to be implicated in BZ withdrawal. However, the precise mechanism involved remains unclear. Collectively, the studies reported show that ipsapirone does not induce the type of withdrawal signs seen with BZs. However, there was no evidence that ipsapirone attenuated BZ withdrawal. It is therefore likely that patients withdrawn from BZs will experience withdrawal if treated with ipsapirone, and that if treated with high doses withdrawal may be exacerbated.An abstract report of some of the data reported here has been published previously (Goudie A.J., Leathley M., McNally J. (1989a))     

The differential effects of prenatal stress in rats on the acoustic startle reflex under baseline conditions and in response to anxiogenic drugs

RATIONALE: The prenatal stress syndrome (PS) is characterized by exaggerated behavioral and physiological responses to stressful stimuli and anxiogenic agents. OBJECTIVES: To characterize the behavioral effects of PS on the acoustic startle reflex (ASR) and to determine the possible role of PS-induced alterations in noradrenergic control of ASR by determining the effects of the alpha2-adrenoceptor antagonists, yohimbine, idazoxan, and RS79948-197. METHODS: PS was induced by exposing pregnant dams to a mild stressor of handling and saline injection (0.1 ml, s.c.) from gestational days 14 to 21. Control dams were left undisturbed throughout pregnancy. Using adult male offspring, all ASR studies consisted of either a 30- or 60-min testing period containing 60 or 120 acoustic startle stimuli trials (95 dB, 50 ms noise burst) at a fixed intertrial interval of 30 s after a 5-min acclimation period. For drug studies, a 3-day repeated measures design was implemented. RESULTS: With the exception of the response to the first startle stimulus on the first day of testing, there were no significant differences in baseline ASR between control and PS offspring. Low doses of yohimbine, idazoxan, and RS79948-197 were anxiogenic in the ASR test in both control and PS offspring. PS offspring were less responsive to higher doses of yohimbine (5 mg/kg) and idazoxan (8 mg/kg) but did not differ from control in their responses to any dose of RS79948-197. CONCLUSIONS: Anxiogenic effects of yohimbine, idazoxan, and RS79978-197, likely mediated via alpha2-adrenoceptor blockade, are similar in control and PS rats. Differences between control and PS rats occurred in the response to higher doses of yohimbine and idazoxan. Non-specific effects of these drugs, such as actions at 5HT1A receptors, may cause their behavioral profile to be altered by PS, and to differ from the highly selective RS79948-197.     

Chronic diazepam treatment: Effect of dose on development of tolerance and incidence of withdrawal in an animal test of anxiety

The effect of the treatment dose of diazepam was assessed on the rate of development of tolerance to diazepam's effects on rat behaviour in the elevated plus-maze test of anxiety. Tolerance developed more rapidly when treatment was with the higher dose: after 14 days when rats were given 2·5 mg/kg/day, but not until 21 days when they were given 1 mg/kg/day. When rats were tested undrugged 36 h after the last of 14 daily doses of diazepam (2·5 mg/kg) they showed behavioural changes indicating increased anxiety. Rats tested at this time with a lower dose of diazepam (1 mg/kg) also showed changes indicating increased anxiety compared with the control scores. This indicates that a more gradual tapering of doses would be necessary to avoid withdrawal responses.     

Driving under light and dark conditions: effects of alcohol and diazepam in young and older subjects

Objectives: Driving at night time increases accident risk due to visual conditions, fatigue and impaired performance. In addition, the use of alcohol and benzodiazepines may enhance the risks related to night-time driving. We studied these aspects of traffic safety in a simulated driving test with young and older drivers. Methods: In a double-blind, crossover, placebo-controlled study, nine young subjects, aged 22–24 years, performed simulated driving in both `light' and `dark' conditions, before and 1.5 h and 4 h after 0.8 g · kg⁻¹ ethanol (EOH) or 15 mg diazepam (DZ). Further, nine older subjects, aged 55–77 years, were similarly tested, but their EOH dose was 0.7 g · kg⁻¹ and the DZ dose was 10 mg. The tests were vigilance assessment on visual analogue scales (VAS), simulated driving under light and dark conditions for 6 min each and digit symbol substitution (DSS). Results: In the young subjects, both EOH and DZ similarly impaired DSS, with DZ causing more subjective drowsiness, clumsiness, mental slowness and poor overall performance than EOH. During simulated driving, both EOH and DZ impaired simple and complex tracking (EOH>DZ) and prolonged reaction times (EOH=DZ). Impairment of performance was practically identical under light and dark conditions. In the older subjects, objective performance on DSS was poorer (−30%) than that of the young ones, and subjective impairment was marginal. During simulated driving, the baseline levels of variables in older subjects showed definite impairment (errors +100% to +500%) when compared with young subjects. Active drugs impaired several variables (EOH>DZ), but the statistical significances were fewer than in young subjects. Increase in reaction errors reached statistical significance, especially while driving in the dark. Otherwise the driving results in light and dark were not notably different. Conclusion: Young subjects drew good baselines but were sensitive to EOH and DZ, whilst the older subjects showed poor baselines but were less sensitive to EOH and DZ. Although the baseline driving and responses to treatments were different in young and older subjects, their driving and psychomotor impairment were unaffected by light conditions. Received: 10 November 1999 / Accepted in revised form: 25 April 2000     

Gamma butyrolactone (GBL) and gamma valerolactone (GVL): similarities and differences in their effects on the acoustic startle reflex and the conditioned enhancement of startle in the rat

Gamma butyrolactone (GBL) is metabolized to gamma hydroxybutyrate (GHB) in the body. GHB is a DEA Schedule 1 compound; GBL is a DEA List 1 chemical. Gamma valerolactone (GVL) is the 4-methyl analog of GBL; GVL is metabolized to 4-methyl-GHB; GVL is NOT metabolized to GBL or GHB. The effects of GBL (18.75-150 mg/kg), GVL (200-1600 mg/kg) or vehicle on the acoustic startle reflex (ASR), and the classically-conditioned enhancement of startle, the Startle Anticipated Potentiation of Startle (SAPS) response were studied in male rats. Both compounds produced a dose-dependent reduction of ASR, with GBL 5-7 times more potent than GVL. In contrast, GBL treatment significantly reduced SAPS at doses that exerted only moderate effects on ASR, whereas GVL exerted little or no effect on the SAPS, except at doses that produced pronounced reductions in Noise Alone ASR. In a second experiment, rats were tested for Noise Alone ASR behavior following treatment with a single mid-range dose of GBL (75 mg/kg), GVL (400 mg/kg) or vehicle; immediately following startle testing the animals were sacrificed and their brains and blood were collected for determination of GHB, 4-methyl-GHB, GBL and GVL. GHB was found in measurable concentrations in all of the blood specimens and 6 (of 8) of the brain specimens from the GBL-treated subjects. 4-Methyl-GHB was found in measurable concentrations in all of the blood and brain specimens of the GVL-treated subjects; the change in startle amplitude was inversely correlated to the brain concentrations of these compounds. These findings confirm the differences in the metabolic fate of GBL and GVL as pro-drugs for the formation of GHB and 4-methyl-GHB, respectively. Moreover, the dissimilarity in effect profile for GBL and GVL on ASR versus SAPS behaviors suggests that different receptor(s) may be involved in mediating these behavioral effects.     

Effects of 8-OH-DPAT,Lisuride and some ergot-related compounds on the acoustic startle response in the rat

Five ergot-related compounds were examined for their effects on the acoustic startle response in the rat. The startle amplitude and the startle latency were registered. 8-Hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT; 0.5–8 mg/kg) and lisuride (0.05–0.8 mg/kg) were found to enhance the startle amplitude, while the mainly DA receptor active ergot derivatives pergolide (0.2–0.8 mg/kg), bromocriptine (5–20 mg/kg) and LY 141865 (5–20 mg/kg) had no, or even the reverse, effect. All five compounds caused a prolongation of the startle latency. The increased startle amplitude caused by 8-OH-DPAT (2 mg/kg) and lisuride (0.2 mg/kg) was successfully antagonized by the 5-HT receptor antagonist methiothepin (0.1 mg/kg) but not by metergoline (1 mg/kg). 5-Hydroxy-L-tryptophan (L-5-HTP; 12.5–50 mg/kg), administered to pargyline- and benserazide-pretreated animals, was included for comparison. The serotonin precursor caused a marked increase in the startle amplitude and a shortening of the startle latency.     

Nonspecific excitatory effects of morphine: Reverse-order precipitated withdrawal and dose-dose interactions

We recently reported that, in naive mice pretreated with naloxone, morphine can cause withdrawal-like signs that seemingly are not mediated by opiate receptors. Such results were confirmed and extended here with another mouse strain. Repetitive vertical jumping could occur irrespective of injection sequence and depended on dose and dose ratio of the two drugs.     

Severity of withdrawal symptomatology in follicular versus luteal quitters: The combined effects of menstrual phase and withdrawal on smoking cessation outcome

Women are at an increased risk of relapse after a smoking cessation attempt. While the reasons for this phenomenon are not fully understood, recent research indicates that both the menstrual cycle and negative symptomatology may play a role. The goal of this study was to describe the association between withdrawal symptoms during attempted smoking cessation, and to investigate the impact of these symptoms on smoking cessation outcomes as defined by 7-day point prevalence at 14 and 30 days. Negative symptoms associated with the premenstrual period were also assessed. Participants (n = 202) were 29.8 (SD ± 6.6) years old and smoked 16.6 (SD ± 5.6) cigarettes per day. They were randomly assigned to quit smoking in the follicular (n = 106) or luteal (n = 96) menstrual phase. We observed several significantly more severe premenstrual and withdrawal symptoms in the luteal phase. Regardless of quit phase, most withdrawal symptoms were associated with an increased risk of relapse at 14 and 30 days post quit date. Participants attempting to quit smoking in the follicular phase who had higher levels of Anger and Craving were more likely to relapse to smoking at 14-days (OR = 2.00, p-value = 0.026; OR = 2.63, p-value = 0.006; respectively). These data suggest that the menstrual cycle may play a role in smoking cessation outcome, as well as in the symptomatology experienced during a cessation attempt.     

The electronic-cigarette: effects on desire to smoke, withdrawal symptoms and cognition

Electronic cigarettes (e-cigarettes) are battery operated devices that deliver nicotine via inhaled vapour. Few studies have evaluated acute effects on craving and mood, and none have explored effects on cognition. This study aimed to explore the effects of the White Super e-cigarette on desire to smoke, nicotine withdrawal symptoms, attention and working memory. Eighty-six smokers were randomly allocated to either: 18 mg nicotine e-cigarette (nicotine), 0mg e-cigarette (placebo), or just hold the e-cigarette (just hold) conditions. Participants rated their desire to smoke and withdrawal symptoms at baseline (T1), and five (T2) and twenty (T3) minutes after using the e-cigarette ad libitum for 5 min. A subset of participants completed the Letter Cancellation and Brown-Peterson Working Memory Tasks. After 20 min, compared with the just hold group, desire to smoke and some aspects of nicotine withdrawal were significantly reduced in the nicotine and placebo group; the nicotine e-cigarette was superior to placebo in males but not in females. The nicotine e-cigarette also improved working memory performance compared with placebo at the longer interference intervals. There was no effect of nicotine on Letter Cancellation performance. To conclude, the White Super e-cigarette alleviated desire to smoke and withdrawal symptoms 20 min after use although the nicotine content was more important for males. This study also demonstrated for the first time that the nicotine e-cigarette can enhance working memory performance. Further evaluation of the cognitive effects of the e-cigarette and its efficacy as a cessation tool is merited.     

安定类药物对失眠症患者日间功能和睡眠质量的影响

目的探讨长期使用安定类药物对失眠症患者日间功能和睡眠质量的影响。方法对35例长期使用安定类药物的老年失眠症患者（研究组）进行整夜多导睡眠图描记和日间功能问卷调查,并与30例未使用安定类药物的老年失眠症患者（对照组）对照分析。结果研究组和对照组日间功能异常者分别为91.4%和30.0%,两组差异有统计学意义（P〈0.05）;多导睡眠图显示研究组睡眠潜伏期缩短、睡眠时间延长、浅睡眠增多、深睡眠和快速眼动期（REM）睡眠减少,与对照组比较差异有统计学意义（P〈0.01）。结论长期使用安定类药物可导致睡眠质量和日间功能下降。     

Dose-response analysis of the behavioral effects of diazepam: II. Psychomotor performance,cognition and mood

The psychomotor, cognitive, and mood effects of orally administered diazepam and placebo were measured over 3.5 h. A total of 120 volunteers were assigned to 12 groups of 10 each, representing the combination of four treatments (placebo, 0.1, 0.2, and 0.3 mg/kg diazepam) and three testing sessions (7 AM, 1 PM, and 7 PM). A variety of cognitive tasks, tapping and postural stability tests, and a mood evaluation scale were used. Psychomotor and cognitive functions showed consistent dose-response effects, while for subjective evaluations, the only effect of dose level was in the duration of sedation. The pattern of impairment of cognitive functions suggests that the drug affects speed rather than accuracy, and it primarily blocks acquisition of new information or skills. Use of repeated testing may therefore be necessary to detect subtle drug effects. Subjects reported no tranquilization, which suggests that the anxiolytic action of the drug cannot be studied in healthy volunteers. There was no circadian influence on the actions of the drug.