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Changes in relative potency among positive GABA(A) receptor modulators upon discontinuation of chronic benzodiazepine treatment in rhesus monkeys.
Psychopharmacology (Berl). 2007 May; 192(1):135-45.P

Abstract

RATIONALE

Benzodiazepine treatment can result in dependence as evidenced by signs of withdrawal upon discontinuation of use.

OBJECTIVE

Positive GABA(A) receptor modulators were examined for their capacity to attenuate flumazenil-like discriminative stimulus effects (i.e., withdrawal) that emerge upon discontinuation of chronic benzodiazepine treatment.

METHODS

Rhesus monkeys receiving chronic diazepam (5.6 mg(-1) kg(-1) 24 h(-1) p.o.) discriminated flumazenil (0.1 mg/kg s.c.) from vehicle.

RESULTS

Upon discontinuation of diazepam treatment, responding switched from the vehicle to the flumazenil lever, although at different times among monkeys. The shorter-acting benzodiazepine lorazepam (3.2 mg(-1) kg(-1) 8 h(-1)) was substituted for diazepam and, 11 h after lorazepam, monkeys consistently responded on the flumazenil lever. Flumazenil-lever responding after acute lorazepam deprivation was attenuated not only by benzodiazepines (lorazepam and midazolam) but also by positive GABA(A) receptor modulators acting at neuroactive steroid (pregnanolone and alfaxalone) and barbiturate sites (pentobarbital). Deprivation-induced responding on the flumazenil lever was not attenuated by low efficacy positive GABA(A) modulators (bretazenil and L-838,417) or non-GABA(A) receptor ligands (ketamine and cocaine). Neuroactive steroids were relatively more potent than other positive GABA(A) receptor modulators in attenuating deprivation-induced flumazenil-lever responding, as compared to their relative potency in monkeys discriminating midazolam and otherwise not receiving benzodiazepine treatment.

CONCLUSIONS

These results suggest that positive GABA(A) receptor modulators acting at different sites attenuate withdrawal induced by discontinuation of benzodiazepine treatment, consistent with previous studies suggesting that the same compounds attenuate flumazenil-precipitated withdrawal. Differences in the relative potency of positive modulators as a function of acute versus chronic benzodiazepine treatment suggest that neuroactive steroids, in particular, are especially potent in benzodiazepine-dependent animals.

Authors+Show Affiliations

Department of Pharmacology, The University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural

Language

eng

PubMed ID

17245585

Citation

McMahon, Lance R., et al. "Changes in Relative Potency Among Positive GABA(A) Receptor Modulators Upon Discontinuation of Chronic Benzodiazepine Treatment in Rhesus Monkeys." Psychopharmacology, vol. 192, no. 1, 2007, pp. 135-45.
McMahon LR, Javors MA, France CP. Changes in relative potency among positive GABA(A) receptor modulators upon discontinuation of chronic benzodiazepine treatment in rhesus monkeys. Psychopharmacology (Berl). 2007;192(1):135-45.
McMahon, L. R., Javors, M. A., & France, C. P. (2007). Changes in relative potency among positive GABA(A) receptor modulators upon discontinuation of chronic benzodiazepine treatment in rhesus monkeys. Psychopharmacology, 192(1), 135-45.
McMahon LR, Javors MA, France CP. Changes in Relative Potency Among Positive GABA(A) Receptor Modulators Upon Discontinuation of Chronic Benzodiazepine Treatment in Rhesus Monkeys. Psychopharmacology (Berl). 2007;192(1):135-45. PubMed PMID: 17245585.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Changes in relative potency among positive GABA(A) receptor modulators upon discontinuation of chronic benzodiazepine treatment in rhesus monkeys. AU - McMahon,Lance R, AU - Javors,Martin A, AU - France,Charles P, Y1 - 2007/01/24/ PY - 2006/10/12/received PY - 2006/12/22/accepted PY - 2007/1/25/pubmed PY - 2007/6/27/medline PY - 2007/1/25/entrez SP - 135 EP - 45 JF - Psychopharmacology JO - Psychopharmacology (Berl) VL - 192 IS - 1 N2 - RATIONALE: Benzodiazepine treatment can result in dependence as evidenced by signs of withdrawal upon discontinuation of use. OBJECTIVE: Positive GABA(A) receptor modulators were examined for their capacity to attenuate flumazenil-like discriminative stimulus effects (i.e., withdrawal) that emerge upon discontinuation of chronic benzodiazepine treatment. METHODS: Rhesus monkeys receiving chronic diazepam (5.6 mg(-1) kg(-1) 24 h(-1) p.o.) discriminated flumazenil (0.1 mg/kg s.c.) from vehicle. RESULTS: Upon discontinuation of diazepam treatment, responding switched from the vehicle to the flumazenil lever, although at different times among monkeys. The shorter-acting benzodiazepine lorazepam (3.2 mg(-1) kg(-1) 8 h(-1)) was substituted for diazepam and, 11 h after lorazepam, monkeys consistently responded on the flumazenil lever. Flumazenil-lever responding after acute lorazepam deprivation was attenuated not only by benzodiazepines (lorazepam and midazolam) but also by positive GABA(A) receptor modulators acting at neuroactive steroid (pregnanolone and alfaxalone) and barbiturate sites (pentobarbital). Deprivation-induced responding on the flumazenil lever was not attenuated by low efficacy positive GABA(A) modulators (bretazenil and L-838,417) or non-GABA(A) receptor ligands (ketamine and cocaine). Neuroactive steroids were relatively more potent than other positive GABA(A) receptor modulators in attenuating deprivation-induced flumazenil-lever responding, as compared to their relative potency in monkeys discriminating midazolam and otherwise not receiving benzodiazepine treatment. CONCLUSIONS: These results suggest that positive GABA(A) receptor modulators acting at different sites attenuate withdrawal induced by discontinuation of benzodiazepine treatment, consistent with previous studies suggesting that the same compounds attenuate flumazenil-precipitated withdrawal. Differences in the relative potency of positive modulators as a function of acute versus chronic benzodiazepine treatment suggest that neuroactive steroids, in particular, are especially potent in benzodiazepine-dependent animals. SN - 0033-3158 UR - https://www.unboundmedicine.com/medline/citation/17245585/Changes_in_relative_potency_among_positive_GABA_A__receptor_modulators_upon_discontinuation_of_chronic_benzodiazepine_treatment_in_rhesus_monkeys_ L2 - https://dx.doi.org/10.1007/s00213-006-0692-9 DB - PRIME DP - Unbound Medicine ER -