Springer Nature is making SARS-CoV-2 and COVID-19 research free. View research | View latest news | Sign up for updates

Ethopharmacological analysis of naloxone-precipitated morphine withdrawal syndrome in rats: a newly-developed “etho-score”


The intensity of opiate withdrawal syndrome in rats is usually quantified on the basis of selected physical signs or global scores. However, the selection criteria of signs and scores have not been subjected to an ethological discussion, hence they appear to be somewhat arbitrary. The objectives of this study were thus: i) to analyse the rat's behaviour during the nalox-one-precipitated morphine withdrawal syndrome, ii) to evaluate the validity of classic methods, and iii) to design a new “etho-score”. Ten rats were implanted with morphine pellets (75 mg×2, SC), all receiving different naloxone doses following a within-subject design (0, 0.01, 0.05, 0.1, 0.5, 1 mg/kg SC). Twenty unexperienced rats and 20 with placebo pellets were injected with either saline or naloxone. Behaviour was videotaped and later analysed by computer-based ethological techniques. The ethogram encompassed 16 patterns displayed by rats during morphine withdrawal. Frequency, duration and latency of each pattern was measured, and a cluster analysis allowed discerning the structure of behaviour. Several physical signs and the Gellert-Holtzman score were also evaluated. The data revealed that writhing responses linearly changed in a dose-related fashion, and mastication was also enhanced after naloxone. Wet-dog shakes and jumping changed following an U-shaped curve. Significant changes in weight loss were found to be dose-dependent, and highly correlated to diarrhea. Learning effects were found to reliably affect exploration, writhing responses and some physical signs. The Gellert-Holtzman score was gradually enhanced after naloxone, being affected by learning as well. Naloxone affected lying and self-care responses in placebo rats. To sum up, the data indicated that: i) classic signs are useful, although most of them are disrupted by high naloxone or affected by learning effects, ii) the Gellert-Holtzman score was validated in this study, and iii) mastication and weight loss are good indicators of naloxone-precipitated morphine withdrawal, representing the basis of an “etho-score” which is herein proposed.

This is a preview of subscription content, log in to check access.


  1. Arnsten AFT, Berridge C, Segal DS (1985) Stress produces opioidlike effects on investigatory behavior. Pharmacol Biochem Behav 22:803–809

  2. Barnett SA (1975) The rat: a study in behavior. Aldine, Chicago

  3. Bläsig J, Herz A (1977) Precipitated morphine withdrawal in rats as a tool in opiate research. In: Essman EB, Valzelli L (eds) Current developments in psychopharmacology, Spectrum Publication, New York, pp 129–149

  4. Bläsig J, Herz A, Reinhold K, Zieglgänsberger S (1973) Development of physical dependence on morphine in respect to time and dosage and quantification of the precipitated withdrawal syndrome in rats. Psychopharmacology 33:19–38

  5. Bläsig J, Holtt V, Bauerle U, Herz A (1978) Involvement of endorphins in emotional hypothermia of rats. Life Sci 28:525–532

  6. Calvino B, Lagowska J, Ben-Ari Y (1979) Morphine withdrawal syndrome: differential participation of structures located within the amygdaloid complex and striatum of the rat. Brain Res 177:19–34

  7. Colgan PW (1978) Quantitative Ethology. Wiley, New York

  8. Espejo EF, Mir D (1993) Structure of the rat's behaviour in the hot plate test. Behav Brain Res 56:171–176

  9. Espejo EF, Stinus L, Cador M, Mir D (1994) Effects of morphine and naloxone on behaviour in the hot plate test: an ethopharmacological study in the rat. Psychopharmacology 113:500–510

  10. Espósito E, Krusewska A, Ossowska G, Samanin R (1987) Noradrenergic and behavioural effects of naloxone injected into the locus coeruleus of morphine-dependent rats and their control by clonidine. Psychopharmacology 93:393–396

  11. Frederickson RCA, Hewes CR, Aiken JW (1976) Correlation between the in vivo and an in vitro expression of opiate withdrawal precipitated by naloxone: their antagonism by 1-(-)-delta9-tetrahydrocannabinol. J Pharmacol Exp Ther 199:375–384

  12. Gellert VF, Holtzman SG (1978) Development and maintenance of morphine tolerance and dependence in the rat by scheduled access to morphine drinking solution. J Pharmacol Exp Ther 205:536–546

  13. Gmerek DE (1988) Physiological dependence on opioids. In: Rodgers RJ, Cooper SJ (eds) Endorphines, opiates and behavioral processes. Wiley, New York, pp 25–54

  14. Gold LH, Stinus L, Inturrisi CE, Koob GF (1994) Prolonged tolerance, dependence and abstinence following subcutaneous morphine pellet implantation in rats. Eur J Pharmacol 253:45–51

  15. Grant EC, Mackintosh JH (1963) A comparison of the social postures of some common laboratory rodents. Behaviour 1:246–259

  16. Higgins GA, Sellers EM (1994) Antagonist-precipitated opioid withdrawal in rats: evidence for dissociations between physical and motivational signs. Pharmacol Biochem Behav 48:1–8

  17. Kerr FWL, Pozuelo J (1971) Suppression of physical dependence and induction of hypersensitivity to morphine by stereotaxic hypothalamic lesions in addicted rats. Proc May Clin 46:653–665

  18. Koob GF, Wall TL (1989) Nucleus accumbens as a substrate for the aversive stimulus effects of opiate withdrawal. Psychopharmacology 98:530–534

  19. Mackintosh JH, Chance MRA, Silverman AP (1977) The contribution of ethological techniques to the study of drug effects. In: Iversen LL, Iversen SD, Snyder SH (eds) Handbook of psychopharmacology. Plenum Press, London, pp 3–35

  20. Maldonado R, Stinus L, Gold LH, Koob GF (1992) Role of different brain structures in the expression of the physical morphine withdrawal syndrome. J Pharmacol Exp Ther 261:669–677

  21. Malin DH, Lake JR, Fowler DE, Hammond MV, Brown SL, Leyva JE, Prasco PE, Dougherty TM (1990) FMRF-NH2-like mammalian peptide precipitates opiate withdrawal syndrome in the rat. Peptides 11:277–280

  22. McAllister KH, Berry MS, Brain PF (1985) Substrate soiled by an unfamiliar conspecific modifies opioid activity in mice placed in novel environments. Physiol Behav 35:465–471

  23. Miczek KA (1982) Ethological analysis of drug action on aggression, defense and defeat. In: Spiegelstein MV, Levy A (eds) Behavioural models and the analysis of drug action. Elsevier, Amsterdam, pp 225–239

  24. Miczek KA, Grossman SP (1972) Effects of septal lesions on inter- and intraspecies aggression in rats. J Comp Physiol Psychol 79:37–45

  25. Mos J, Olivier B, Van der Poel AM (1987) Modulatory actions of benzodiazepine receptor ligands on agonistic behavior. Physiol Behav 41: 265–278

  26. Olivier B (1981) Selective anti-aggressive properties of DU 27725: ethological analyses of intermale and territorial aggression in the male rat. Pharmacol Biochem Behav 14:61–77

  27. Poshivalov VP (1981) Pharmaco-ethological analysis of social behaviour in isolated mice. Psychopharmacol Aggress Soc Behav 14:53–59

  28. Roth KA, Katz RJ (1980) Stress, behavioral arousal and open field activity: a reexamination of emotionality in the rat. Neurosci Biobehav Rev 3:247–263

  29. Short R, Horn J (1984) Some notes on factor analysis of behavioural data. Behaviour 90:203–214

  30. Silverman AP (1965) Ethological and statistical analysis of drug effects on the social behaviour of laboratory rats. Br J Pharmacol Chemother 24:579–590

  31. Slater PJB (1978) Data collection. In: Colgan PW (ed) Quantitative ethology. Wiley, New York, pp 7–24

  32. Spanagel R, Osborne FXA, Bartl C, Shippenberg TS (1994) Endogenous k-opioid systems in opiate withdrawal: role in aversion and accompanying changes in mesolimbic dopamine release. Psychopharmacology 115:121–127

  33. Stinus L, Le Moal M, Koob GF (1990) Nucleus accumbens and amygdala are possible substrates for the aversive stimulus effects of opiate withdrawal. Neuroscience 37:767–773

  34. Stinus L, Cador M, Le Moal M (1992) Interaction between endogenous opioids and dopamine within the nucleus accumbens. Ann N Y Acad Sci 654:254–273

  35. Tremblay EC, Charton G (1981) Anatomical correlates of morphine withdrawal syndrome: differential participation of structures located within the limbic system and striatum. Neurosci Lett 23:137–142

  36. Von Voigtlander PF, Lewis RA (1983) A withdrawal hyperalgesia test for physical dependence: evaluation of mu and mixed-partial agonists. J Pharmacol Meth 10:277–282

  37. Wei E, Loh HH, Way EL (1972) Neuroanatomical correlates of morphine dependence. Science 1771:616–617

  38. Wei E, Loh HH, Way EL (1973) Quantitative aspects of precipitated abstinence in morphine dependent rats. J Pharmacol Exp Ther 184:398–403

Download references

Author information

Correspondence to E. Fdez Espejo.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Espejo, E.F., Cador, M. & Stinus, L. Ethopharmacological analysis of naloxone-precipitated morphine withdrawal syndrome in rats: a newly-developed “etho-score”. Psychopharmacology 122, 122–130 (1995).

Download citation

Key words

  • Behaviour
  • Morphine
  • Naloxone
  • Withdrawal syndrome
  • Ethopharmacology
  • Rat