Doses Of Chlordiazepoxide Research Articles

Chlordiazepoxide-induced working memory impairments: Site specificity and reversal by flumazenil (R015-1788)

The following studies examined the dose and time dependence, site specificity, and reversibility of chlordiazepoxide (CDP)-induced working memory impairments in adult male Sprague-Dawley rats. The rats were tested in a delayed non-match-to-sample radial-arm maze task in which a 1-h delay was imposed between the first four (predelay) and all subsequent (postdelay) arm choices. Intraperitoneal (ip) injection of 2.5 or 5.0 but not 1.25 mg/kg CDP immediately following the predelay session impaired performance in the task. CDP increased the number of errors and decreased the number of correct choices during the postdelay session. The observed working memory impairments also appeared to be site specific since injection of CDP into the medial septum, but not into the anterior amygdala nuclei, immediately following the predelay session also impaired working memory in a dose-related manner. Furthermore, there was a time window for CDP-induced working memory impairments since intraseptal injection of the drug immediately but not 15 min following the predelay session disrupted memory. This observation suggests that the performance deficits reflect disrupted working memory and not proactive effects on performance or the induction of state-dependent learning. In the final experiment, rats were injected ip with either saline or an amnestic dose of CDP (5.0 mg/kg) following the predelay session and then were immediately infused with 10 nmol flumazenil (RO15-1788), a benzodiazepine receptor antagonist or vehicle, into either the medial septum or anterior nuclei of the amygdala. Intraseptal injection of flumazenil prevented the working memory impairments produced by ip injection of CDP. In contrast, intra-amygdala injection of flumazenil did not attenuate, enhance, or modify the CDP-induced working memory impairment. These observations suggest that CDP disrupts working memory by interacting with benzodiazepine receptors in the medial septum.

Effects of the 5-HT3 antagonist ICS 205-930 on benzodiazepine withdrawal signs in rats.

Effects of the 5-HT3 antagonist ICS 205-930 on chlordiazepoxide (CDP) withdrawal were assessed in rats treated for 21 days with doses of CDP up to 40mg/kg/day (b.i.d.). Withdrawal signs recorded were body weight and 24h food intake, which both fell during withdrawal and then recovered. ICS 205-930 (0.001-1.0mg/kg) was administered b.i.d. during withdrawal. At no dose over the wide range tested did ICS 205-930 reduce withdrawal signs. These data contrast with published findings with the 5-HT3 antagonist ondanestron, some of which indicated that ondansetron completely alleviated the "anxiogenic" suppression of exploratory behaviour observed during benzodiazepine (BZ) withdrawal. Possible reasons for these differing findings are discussed. Collectively, these findings suggest that 5-HT3 antagonists may have limited utility in the clinical treatment of BZ withdrawal.

Microgram doses of chlordiazepoxide and diazepam do not increase punished responding in the rat

Microgram doses of chlordiazepoxide and diazepam injected intraperitoneally (i.p.) have been reported to change rodent behavior, notably in two observational procedures that predict anxiolysis. We tested half-log doses from 0.03 to 10 mg/kg in the Geller-Seifter conflict preparation in the rat. Only doses in the milligram range showed any tendency to increase punished responding. The results do not support the hypothesis that microgram doses might be anxiolytic. © 1992 Wiley-Liss, Inc.

Comparison of the effects of buspirone and chlordiazepoxide on differential reinforcement of low rates of response

Buspirone is a novel agent which is clinically effective as an anxiolytic but which lacks the muscle relaxant, anticonvulsant and sedative effects of classical anxiolytics. It also lacks the full spectrum of action of classical anxiolytics in animal models of anxiety based on shock and novelty. In the present paper the effects of buspirone and chlordiazepoxide were tested on acquisition of differential reinforcement of low rates of response (DRL). This schedule involves the suppression of behaviour by reward omission and has shown consistent effects with classical anxiolytics. Buspirone was tested at doses of 0.3, 1.1 and 3.3 mg/kg i.p. and chlordiazepoxide at 5 and 20 mg/kg. Buspirone produced effects similar to those of chlordiazepoxide on accuracy of DRL responding. However, the size of the observed effects of buspirone was small even in relation to the 5 mg/kg dose of chlordiazepoxide and did not appear to be directly related to dose. Chlordiazepoxide increased overall rate of responding, while buspirone decreased it. Buspirone appears to show only limited conformity with benzodiazepines in animal models of anxiety and this result appears independent of the reinforcer used in the task.

Effects of chlordiazepoxide and β-carboline 3-carboxylic acid ethyl ester on non-suppressed and minimally-suppressed responding in the squirrel monkey

Lever-pressing of squirrel monkeys was maintained under a multiple fixed-interval (FI) 5-min schedule of food presentation. In one component, responding was suppressed to various degrees by the presentation of electric shock following each 30th response. When responding was either substantially or minimally suppressed, intermediate doses of chlordiazepoxide (CDAP, 1–30 mg/kg) increased both suppressed and non-suppressed responding. β-carboline 3-carboxylic acid ethyl ester (β-CCE, 0.1–3 mg/kg) had little effect at low to intermediate doses (0.1–0.3 mg/kg) and decreased both minimally-suppressed and non-suppressed responding to a comparable extent at higher doses. Repeated daily dosing with β-CCE (up to 10 mg/kg) resulted in rapid tolerance to its rate-decreasing effects. As agonists do not typically exhibit rapid tolerance for anxiolytic efficacy, the current results suggest that some behavioral effects of inverse agonists may not be strictly opposite those of benzodiazepines.

Antipunishment effects of acute and repeated administration of phencyclidine and NPC 12626 in rats

The effects of phencyclidine (PCP) and NPC 12626 on punished responding were examined using a modified Geller-Seifter procedure in rats. Both drugs are known to antagonize N-methyl-D-aspartate (NMDA) receptor mediated neurotransmission, albeit at different sites on the NMDA receptor complex. Rats were trained to lever press for food reinforcement under a multiple schedule, with responding in one component reinforced under a fixed-interval 60-sec schedule, while each response in the other component resulted in both food and brief electric shock. Both PCP and NPC 12626 produced selective increases in punished responding, although the effects were not as large as those produced by chlordiazepoxide. Repeated daily administration of each of these drugs for 6 days resulted in increases in punished responding during different portions of the treatment. A 5 mg/kg dose of chlordiazepoxide produced increases over the last 2 days of administration. PCP (2 mg/kg) produced an increase only during the second session, whereas NPC 12626 (30 mg/kg) produced increases for all but the first and fifth days of the 6-day regimen. Both competitive and noncompetitive NMDA antagonists can have antipunishment effects in this model.

Cue dimensionality in the three-choice pentylenetetrazole-saline-chlordiazepoxide discrimination task

Sprague-Dawley rats were trained in a three-choice drug discrimination task utilizing 5mg/kg chlordiazepoxide (CDP), saline (SAL), and 15mg/kg pentylenetetrazole (PTZ) as stimulus conditions. Generalization tests of the three training conditions resulted in exclusively injection-appropriate lever selection. Cross-generalization tests with PTZ or CDP resulted in dose-dependent lever selections confined to the training drug and SAL levers. Morphine and ethanol cross-generalization tests produced saline-appropriate responding, whereas cocaine and caffeine produced PTZ-appropriate responding at high doses. Tests conducted after concomitant administration of both training drugs demonstrated a reciprocal antagonism between the two drugs. More importantly, when the training dose of CDP was held constant and combined with increasing doses of PTZ, a shift from CDP- to PTZ-appropriate responding through a dose range of exclusive SAL-appropriate responding was demonstrated. Overt behavioral indices of seizure activity occurred at dose combinations that engendered only saline responding, but PTZ-appropriate responding did not correspond with the development of overt seizure episodes. These data suggest that the PTZ discriminative cue in the present three-choice paradigm is not primarily linked to its proconvulsant effects. The data are discussed in terms of an hypothesis in which the discriminable interoceptive cues for PTZ and CDP lie at opposite ends of a single continuum that has a neutral centroid, and this continuum more likely reflects an anxiolysis-anxiogenesis dimension than an anticonvulsant-seizure dimension.

Effects of buspirone on fixed interval responding in rats

Buspirone is a novel anxiolytic which does not share the muscle relaxant, anticonvulsant and sedative properties of classical anxiolytics such as the benzodiazepines. Its effects in different animal models of anxiety are also variable. The present experiments investigated the effects of buspirone on a fixed interval 60 s schedule of reinforcement (FI). In experiment 1, four doses of buspirone (10, 3.3, 1.1 and 0.3 mg/kg, i.p.) and two doses of chlordiazepoxide (5 and 20 mg/kg, i.p.) were administered to separate groups of rats throughout acquisition of the FI task. In experiment 2, four doses of buspirone (1.1, 0.3, 0.1 and 0.03 mg/kg, i.p.) and a single dose of chlordiazepoxide (5 mg/kg, i.p.) were used. Chlordiazepoxide generally released responding. At higher doses (1.1 mg/kg and above) buspirone suppressed responding in the later parts of the FI interval. The effects of lower doses were variable but included some response release in the later parts of the FI interval. At no dose did buspirone release responding at the beginning of the FI interval. The experiments show that buspirone differs qualitatively as well as quantitatively from chlordiazepoxide and that current animal models based on behavioural inhibition may need to be used with considerable care if detection of novel anxiolytics is to be ensured.

Anxiolytic effects of benzodiazepines in amygdala-lesioned rats

The role of the amygdala in the anxiolytic action of benzodiazepines was examined. Performance on a water-licking conflict paradigm was tested in rats with localized damage to the central nucleus of the amygdala (ACE) or with general damage to the entire amygdaloid complex. The effects of the benzodiazepine chlordiazepoxide (2.5-20.0 mg/kg) on conflict behavior in these animals was also examined. Electrolytic lesions of either ACE or of the entire amygdaloid complex resulted in a pronounced increase of punished responding, an effect that persisted for at least 12 sessions postoperatively. After shock levels were adjusted in the lesioned groups to match their baseline punished behavior to that of the controls, various doses of chlordiazepoxide were administered. Not only did the lesioned animals show an increase in punished behavior in response to the drug, they were more sensitive than controls to the lower drug doses. A complete model of anxiolytic action may have to include both mechanisms that block anxiogenic regions and those that activate anxiolytic regions.

Effects of buspirone and chlordiazepoxide on plasma catecholamine and corticosterone levels in stressed and nonstressed rats

The effects of intragastric administration of the prototypical benzodiazepine (BDZ) anxiolytic drug chlordiazepoxide (CDP) and the non-BDZ anxiolytic agent buspirone (BUSP) on basal and stress-elevated plasma noradrenaline (NA), adrenaline (A) and corticosterone (CS) contents were investigated. Acute dosing of CDP (1–27 mg/kg) produced dose-related increases in basal CS secretion but was without effect on basal NA levels. The high dose of CDP caused a slight short-term A increase. Dose-dependent increases in plasma A, NA and CS contents were observed after acute treatment with BUSP (2 and 20 mg/kg). A medium dose of CDP (9 mg/kg) attenuated the stress-induced CS and A elevations. High doses of CDP that elevated basal CS release prevented a further increase of CS by stress and inhibited the NA and A response to stress. BUSP (2 and 20 mg/kg) was not effective in decreasing the stress-elicited rise of CS, NA or A. Conversely, the 20 mg/kg dose of BUSP enhanced the stress-induced A response. Repeated administration of CDP (9 mg/kg/day for six days) produced tolerance to the elevation of basal CS triggered by acute CDP treatment, but increased the efficacy of the drug's CS and A attenuating action in stressed rats. Repeated administration of BUSP (2 mg/kg/day for six days) also produced tolerance to the acute BUSP-induced effect on basal CS release, but did not affect the stress-induced CS, NA and A responses. It is concluded that the clinically effective anxiolytic BUSP does not have the BDZ-like property to inhibit stress-induced elevations in CS, NA and A. Furthermore, the present data support other evidence that activation of 5-HT 1A receptor mechanisms increases plasma catecholamine and corticosterone concentrations.

Dose-response analysis of the effects of buspirone on rearing in rats

The effects of buspirone were tested on rearing in an open field. Six different doses of buspirone (10, 3.3, 1.1, 0.3, 0.1 and 0.04 mg/kg) and a single dose of chlordiazepoxide (5 mg/kg) were administered i.p. to separate groups of rats. Buspirone produced a dose-dependent decrease in rearing in the range 0.04-10 mg/kg, whereas only the higher doses (10 and 3.3 mg/kg) decreased ambulation significantly. Chlordiazepoxide reduced rearing to an extent equivalent to 1 mg/kg of buspirone. Together with data in the literature, the results suggest that 5-HT1A agonists affect rearing at lower doses than ambulation; that the effects of buspirone in the open field are similar to classical anxiolytics; and that changes in rearing may be more closely related to anxiolytic than muscle relaxant, anti-convulsant and other GABA-mediated effects of the classical anxiolytics.

Ethanol effects on delayed spatial matching as modeled by a negative exponential forgetting function

Performance on delayed matching-to-position as a function of ethanol was investigated in rats and dose effects assessed by fitting an exponential decay model of forgetting to signal detection sensitivity scores. Three ethanol doses (0.25, 0.50, and 0.75 g/kg) and one isovolume saline control were examined. For further comparison, one dose of chlordiazepoxide (CDP; 5 mg/kg) and its saline control were also given. Forgetting functions were reasonably well described by the decay model under all treatment conditions. In addition, the functions's decay constant (-b) proved to be differentially sensitive to both drug and dose effects. Reduced decay estimates were obtained following the two lowest ethanol doses, the reduction being statistically significant for the 0.25 g/kg dose. In contrast, the function estimate of initial sensitivity, the intercept parameter (SI0), was not significantly affected by ethanol. Consistent with the low-dose ethanol effects, CDP significantly decreased the value of the decay parameter while leaving the intercept parameter unaffected. But unlike ethanol, the variance accounted for by the model for the individual data was less following CDP administration. Drug effects were interpreted using the exponential decay model of forgetting, and the results suggest independent discriminative control over SI0 and b. The significant effect of the low-dose sedative-hypnotics upon b, with no attendant effects upon SI0, is suggested to result from enhanced, spontaneous, delay interval mediation.

Anxiolytic potential of a microgram dose of chlordiazepoxide in the open-field test

Diazepam, when administered in very low doses (100 μg/kg), can induce a specific inhibition of coarse and ambulation activities in the rat, suggesting a novel mechanism of action occuring in the microgram dose range. This study fails to reproduced the same effects with chlordiazepoxide. On the contrary, greater stimulant and anxiolytic effects were measured with the lowest dose tested (0.1 mg/kg). These results demonstrate that the familiar effects of benzodiazepines should not be extrapolated uncritically to lower dose ranges without empirical testing.

Brain benzodiazepine receptor-mediated effects on plasma catecholamine and corticosterone concentrations in rats

The effects of the benzodiazepine (BDZ) receptor agonist chlordiazepoxide (CDP) and antagonist flumazenil (Ro 15-1788), given alone and in combination, on basal and novel environment stress (NES)-elevated plasma noradrenaline (NA), adrenaline (A) and corticosterone (CS) contents were investigated. When administered on their own, a medium dose of CDP (2.5 mg/kg) and a moderate dose of flumazenil (5 mg/kg) did not affect basal hormone levels. However, flumazenil potentiated the NES-induced CS elevation and suppressed the NA rise in response to NES. The 2.5 mg/kg dose of CDP attenuated the NES-elicited rise of CS and A, without changing the NES-enhanced NA concentrations. High doses of CDP (10 and 12.5 mg/kg), which elevated basal CS levels, prevented a further CS increase by NES and completely abolished the NA and A response to NES. The CDP effects on CS and NA were antagonized by pretreatment with flumazenil, in contrast to the CDP effect on A which was not blocked. The data indicate that brain (central-type) BDZ receptor systems are involved in regulating the neurosympathetic and adrenocortical, but not adrenomedullary, responses to mild stress.

Age and anxiety: Increased anxiety, decreased anxiolytic, but enhanced sedative, response to chlordiazepoxide in old rats

AbstractThe effects of chlordiazepoxide (7.5 mg/ kg) were assessed on the performance of young (3 months) and old (12 months) hooded Lister rats in the elevated plus‐maze test of anxiety. In young animals chlordiazepoxide significantly increased the percentage of entries onto open arms and the percentage of time spent on the open arms of the plus‐maze, measures that reflect its anxiolytic action. In the young animals this dose of chlordiazepoxide did not change the total number of arm entries, a measure that reflects its sedative action. However, in the old animals the only significant effect was a reduction in total arm entries. The effects of ageing on performance in the plus‐maze was assessed by testing rats at 3, 6, 9 and 12 months of age. Between 9 and 12 months the rats showed a significant decrease in the percentage of entries onto open arms and in the percentage of time spent on the open arms, indicating an increase in this measure of anxiety. Thus it seems that old rats might have an increase in their baseline measures of anxiety, coupled with a reduced anxiolytic response to benzodiazepines.

Chronic treatment with ethanol or chlordiazepoxide alters the metabolism of chlordiazepoxide

Although chronic ethanol administration in C57BL/6J mice did not cause an induction of ethanol metabolism, it altered the metabolism of chlordiazepoxide (CDP). Significantly lower blood levels of CDP, but higher levels of N-desmethyl CDP (NDCDP), were observed in ethanol-dependent mice compared to pair-fed controls during the first hour after CDP injection. Mice treated chronically with CDP showed significantly lower blood levels of CDP and NDCDP than pair-fed controls after a test dose of CDP. In response to an injection of ethanol, the CDP-dependent mice had lower blood alcohol levels (BAL) than the pair-fed controls, but the rate of fall of BAL was not different in the two groups. Thus, chronic CDP treatment affected the absorption and distribution of ethanol. These results provide a metabolic basis for the manifestations of CDP tolerance and ethanol cross-tolerance that have been reported in CDP-dependent mice.

Independence of benzodiazepine and opiate action in the suppression of isolation distress in rat pups.

To determine whether benzodiazepines (BDZs) quiet isolation distress in 10-day-old rat pups by causing a release of endogenous opioids, a blockade of the effects of chlordiazepoxide (CDP) by the opiate antagonist naltrexone (NLX) was sought. Nonsedating doses of morphine (MOR) (0.125 mg/kg) and CDP (2.0 mg/kg) were equally effective in reducing ultrasonic vocalizations and other indices of isolation distress. Appropriate blocking agents NLX, (0.5 mg/kg) against MOR and Ro 15-1788 (4.0 mg/kg) against CDP returned distress measures to levels of saline-treated rat pups. However, NLX failed to reverse the quieting effects of CDP. If CDP potentiates endogenous opioid release, then NLX should block the CDP effect. A higher dose of CDP did not reveal a release of endogenous opioids, and a higher dose of NLX did not antagonize CDP. The quieting effects of BDZs on isolation distress do not appear to be mediated by the opiate system.

Alcohol withdrawal in the elderly.

The phenomenon of alcohol withdrawal has seldom been studied in subgroups of patients in withdrawal. We developed a rating scale for measuring alcohol withdrawal that we found to be reliable and valid. The scale, when applied to young (ages 21-33, N = 24) and elderly (ages 58-77, N = 26) groups of patients in alcohol withdrawal, indicated that the elderly group initially had a more severe withdrawal for which they received higher doses of chlordiazepoxide.

MR/Har and MNRA/Har Maudsley rat strains: Differential response to chlordiazepoxide in a conflict task

The Maudsley Reactive (MR/Har) and Non-Reactive (MNRA/Har) rat strains, selectively bred for differences in open field defecation, have also been shown to differ in their baseline behavior in the Conditioned Suppression of Drinking (CSD) procedure, a second “model” behavior for the study of anxiety and/or emotionality in rats. The present studies were designed to compare the responsiveness of these two strains to the typical antianxiety agent chlordiazepoxide in the CSD paradigm. In daily 10-minute sessions, water-deprived rats were trained to drink from a tube that was occasionally electrified (0.5 mA), electrification being signaled by a tone. Consistent with previous reports, after several weeks of CSD testing, MNRA/Har rats accepted significantly more shocks than did MR/Har rats during control (nondrug) sessions. In both strains, the number of shocks accepted was inversely related to the intensity of the shock used (0.25–1.0 mA), with MNRA/Har rats accepting significantly more shocks than MR/Har rats at all intensities examined. The effects of various doses (1.25–28.4 mg/kg, IP) of chlordiazepoxide were determined in subjects of the MNRA/Har strain at the original training intensity (0.5 mA), while a lower intensity (0.25 mA) was utilized in MR/Har rats. Although punished responding in control (i.e., nondrug) CSD sessions did not differ under these conditions, MNRA/Har rats were found to be more responsive to the anticonflict effects of chlordiazepoxide than rats of the MR/Har strain. This strain difference in anticonflict efficacy of chlordiazepoxide was quite dramatic, with MNRA/Har rats accepting twice as many shocks as MR/Har rats following maximally effective doses of chlordiazepoxide. Low doses of chlordiazepoxide increased water intake slightly, while higher doses decreased water intake. Surprisingly, the chlordiazepoxide-induced depression of water intake was greater in rats of the MR/Har strain. Thus, these Maudsley Reactive and Non-Reactive rat strains, bred originally for their differences in open field behavior, also differ markedly in their responsiveness to chlordiazepoxide in the CSD paradigm. These findings further support the hypothesis that the MR/Har and MNRA/Har rat strains may represent a genetically-based “animal-model” for the study of emotionality and/or anxiety.

The GABA/benzodiazepine receptor complex in the central amygdalar nucleus and stress ulcers in rats

The effects of bilateral microinjections of chlordiazepoxide and GABA into the central amygdalar nucleus on gastric ulcer formation induced by cold-restraint were examined in chronically implanted Wistar rats. Higher doses of chlordiazepoxide (20 and 30 micrograms/amygdala) significantly reduced stress ulcer development, whereas a lower dose (2.5 micrograms) produced a nonsignificant increase in ulcer severity. A similar dose/response pattern was observed following GABA administration. The benzodiazepine receptor antagonist Ro15-1788, applied to the amygdala, abolished the protective effects of both chlordiazepoxide and GABA. In addition, when Ro15-1788 (10 micrograms) was injected into the amygdala by itself, it aggravated the gastric stress pathology. However, a lower dose (5 micrograms) had an attenuating effect, opposite to the pattern of effects produced by chlordiazepoxide and GABA. The role of the amygdalar GABA-benzodiazepine receptor complex in stressful conditions is discussed.