Psicothema was founded in Asturias (northern Spain) in 1989, and is published jointly by the Psychology Faculty of the University of Oviedo and the Psychological Association of the Principality of Asturias (Colegio Oficial de Psicólogos del Principado de Asturias).
We currently publish four issues per year, which accounts for some 100 articles annually. We admit work from both the basic and applied research fields, and from all areas of Psychology, all manuscripts being anonymously reviewed prior to publication.
J. Francisco Navarro, Carmen Pedraza, Guadalupe Dávila y Mercedes Martín López
Universidad de Málaga
This study was designed to examine the effect of acute administration of gammahydroxybutyric acid (GHB; 150-250 mg/kg, i.p), a central neurotransmissor or neuromodulator, on catalepsy behaviour in female mice. Catalepsy was measured by means of the bar test. An aluminium bar of 5 mm in diameter was placed 4 cm above the floor. Animal`s forepaws were gently put on the bar and the time it took the animal to place at least one paw on the floor was measured. If 1 min elapsed without movement, the test was interrumped. Catalepsy was evaluated 30 and 60 min after administration of GHB or saline (control group). The results indicated that GHB (225 and 250 mg/kg) significantly increased catalepsy of female mice, an action probably mediated by the interaction between GHBergic and dopaminergic neurons in striatum.
Efectos de la administración de ácido gammahidroxibutírico sobre la conducta de catalepsia en ratones hembras. El objetivo de este trabajo fue examinar el efecto de la administración aguda de ácido gammahidroxibutírico (GHB; 150-200 mg/kg, i.p), un neurotransmisor o neuromodulador central, sobre la conducta de catalepsia en ratones hembras. Para la evaluación de la catalepsia se utilizó el «test de la barra» (de 5 mm de diámetro y colocada a 4 cm sobre el suelo). Las patas de los animales fueron suavemente colocadas sobre dicha barra, contabilizándose el tiempo que el animal tardaba en situar al menos una pata sobre el suelo. Si transcurría 1 minuto sin movimiento, la prueba era interrumpida. La catalepsia fue evaluada 30 y 60 minutos tras la administración de GHB o suero salino (grupo control). Los resultados indicaron que el GHB (225 y 250 mg/kg) incrementó significativamente la catalepsia de los ratones hembras, una acción probablemente mediada a través de las interacciones entre neuronas GHBérgicas y dopaminérgicas en el estriado.
Gammahydroxybutyric acid (GHB) is a GABA metabolite which can traverse the blood-brain barrier after peripheral injection. It satisfies many of the criteria for consideration as a neurotransmitter, being present in micromolar quantities in numerous brain regions as well as in several peripheral organs. GHB high affinity receptors are located only in neurons, specially in hippocampus, cortex, striatum, olfactory bulbs and tubercles, substantia nigra and area tegmental ventral (Cash, 1994; Maitre, 1997; Tucnnicliff, 1997).
From a clinical point of view, GHB has been used as anesthetic drug, for treatment of narcolepsy (Lammers et al., 1993) and to alleviate the alcohol/opiate dependence (Gallimbeti et al., 1989). Likewise, this compound is a reliable stimulant of slow-wave sleep in normal subjects, simultaneously enhancing sleep related growth hormone secretion (van Cauter et al., 1997). Recently, it has been characterized as an emerging drug of abuse that cause physical dependence (Galloway, 1997). In this sense, its prolonged use at high doses may lead to a withdrawal syndrome, which resolves without sequelae.
In animals, it has been demonstrated that GHB posessess rewarding properties (evaluated by a conditioned place preference paradigm) (Martellotta, Fattore, Cossu and Fratta, 1997). Moreover, GHB exhibits a wide range of pharmacological effects, including hypothermia (Kaufmann, Porrino and Nelson, 1990), epilepsy seizures (Banerjee, Hirsch and Snead, 1993), a decrease of aggression (Navarro and Pedraza, 1996), anxiolytic properties (Schmidt et al., 1998) and catalepsy (Navarro et al., 1996; 1998). This cataleptic behaviour observed in rodents after GHB administration is reverted by NCS-382, a GHB receptor antagonist (Schmidt et al., 1991).
Although catalepsy has been observed in rats (Snead and Bearden, 1980; Hechler et al., 1993) and mice (Navarro et al., 1996; 1998) using different types of behavioural tests, all studies have been carried out in male rodents. Therefore, this experiment was designed to examine the effect of acute administration of GHB (150-250 mg/kg) on catalepsy behaviour in female mice.
Materials and methods
60 CD strain albino female mice weighing 25-35 g were obtained from CRIFFA (Barcelona, Spain). Animals were housed in transparent plastic cages (24 x 13.5 x 13 cm) in groups of five under standardised lighting conditions (light: 20:00-8:00), a constant temperature and laboratory chow and tap water available ad libitum. All animals underwent a seven-day adaptation period to the laboratory before experimental treatments began.
GHB (Sigma Laboratories, Madrid, Spain) was diluted in saline and administered acutely in five doses (150, 175, 200, 225 and 250 mg/kg, i.p) to female mice. Control animals received 0.9% sodium chloride (vehicle).
Catalepsy was measured by means of the bar test. An aluminium bar of 5 mm in diameter was placed 4 cm above the floor. Animals’ forepaws were gently put on the bar and the time it took the animal to place at least one paw on the floor was measured. If 1 min elapsed without movement the test was interrupted. Successive behavioural evaluations of catalepsy were carried out 30 and 60 minutes after the administration of GHB or saline. Between determinations, the mice were kept in their home cages. Individual animals were tested in a random order.
A determination of the phase of the estrous cycle was immediately made for each animal after the catalepsy test . This determination was carried out according with the procedure described by Waynforth and Flecknell (1992).
Nonparametric Kruskal-Wallis tests were used to assess the variance of the catalepsy scores over different treatment groups. Subsequently, appropriate paired comparisons were carried out using Mann-Whitney U-tests to contrast the behavior in the different treatment groups. Wilcoxon tests were also employed to contrast the catalepsy scores of mice at different behavioural evaluations used. A value of p<0.05 was considered to be statistically significant.
Results and Discussion
Table 1 illustrates the mean scores of catalepsy shown by female mice after single administration of GHB. Kruskal-Wallis analysis showed that there was significant variance in catalepsy scores over different treatment groups (p<0.05). Paired comparisons using Mann-Whitney U -tests revealed that bar catalepsy scores (225-250 mg/kg) increased significantly following GHB administration, in comparison with mice treated with saline, at test carried out 30 min after injection (p<0.02). Catalepsy was never observed in saline-treated mice.
Furthermore, Wilcoxon tests showed that catalepsy scores (225 and 250 mg/ kg) for GHB-treated female mice were always clearly higher when tested at 30 min, as compared with mice tested 60 min after administration of the drug (p<0.05).
As Table 1 shows, GHB (225 and 250 mg/kg) provoked a marked but short lasting catalepsy with a peak of action within 30 min. However, 60 min after GHB administration this cataleptic effect had disappeared. These results are in concordance with a recent study using male mice in which a dose-dependent effect on catalepsy was described (Navarro et al., 1996). Moreover, like in our study, a clear catalepsy was also observed in male mice from 225 mg/kg of the drug.
Catalepsy is considered as an appropriate rodent model for detecting the extrapyramidal side effects of antipsychotic/neuroleptic drugs (Hoffman and Donovan, 1995; Navarro, Manzaneque, Martín and Vera, 1997), an action mainly mediated by dopamine neurons located in striatum (Sanberg, 1980). The cataleptogenic effect of GHB could be related to its action on striatal dopaminergic neurons. In fact, GHB is considered to be an inhibitor of striatal dopamine release in awake animals (Howard and Feigenbaum, 1997) and it has also been shown to have antidopaminergic activity (Navarro and Pedraza, 1996) as well as effects similar to those of typical antipsychotics (Beardsley, 1996). In sum, our findings might be in aggreement with the view that GHB receptors interact with central dopamine D2 transmission.
The phase of estrous cycle (proestrus, estrus, diestrus or metaestrus) was specifically identified in vaginal smears taken immediately after the experiment in each mouse. During catalepsy test, most of female mice were either in diestrus or in metaestrus (progestational stages). Although it cannot be definitely excluded that the cataleptic effect of GHB in females may be partially modulated by sexual hormone changes that occur during the estrous cycle, catalepsy behaviour does not appear to vary significantly during phases of the cycle in rodents (Kazandjian et al., 1988).
Banerjee, P.K., Hirsch, E. and Snead, O.C. (1993). Gammahydroxybutyric acid induced spike and wave discharges in rats: relation to high-affinity [3H] gamma-hydroxybutyric acid binding sites in the thalamus and cortex. Neuroscience, 56, 11-21.
Beardsley, P.M. (1996). Evaluation of the discriminative stimulus and reinforcing effects of gammahydroxybutyrate (GHB). Psychopharmacology, 127, 315-322.
Cash, C.D. (1994). Gammahydroxybutyrate: An overview of the pros and cons for it being a neurotransmitter and/or a useful therapeutic agent. Neuroscience and Biobehavioral Reviews, 18, 291-304.
Gallimberti, L., Canton, G., Gentile, N.,Cibin, M., Fadda, F., Ferri, M., Ferrara, S.D. and Gessa, G.L. (1989). Gamma-hydroxybutyric acid for treatment of alcohol withdrawal syndrome. Lancet, 30, 787-789.
Galloway, G.P., Frederick, S.L., Staggers, F.E. Jr., Gonzáles, M., Stalcup, S.A. and Smith, D.E. (1997). Gamma-hydroxybutyrate: an emerging drug of abuse that causes physical dependence. Addiction, 92, 89-96.
Hechler, V., Peter, P., Gobaille, S., Bourguignon, J.J., Schmitt, M., Ehrardt, J.D., Mark, J. and Maitre, M. (1993). Gamma-hydroxybutyrate ligands possess antidopaminergic and neuroleptic-like activities. Journal of Pharmacology and Experimental Therapeutics, 264, 1406-1414.
Hoffman, D.C. and Donovan, H. (1995). Catalepsy as a rodent model for detecting antipsychotic drugs with extrapyramidal side effect liability. Psychopharmacology, 120, 128-133.
Howard, S.G. and Feigenbaum, J.J. (1997). Effect of gamma-hydroxybutyrate on central dopamine release in vivo. A microdialysis study in awake and anesthetized animals. Biochemical Pharmacology, 53, 103-110.
Kaufmann, E.E., Porrino, L.J. and Nelson, T. (1990). Pyretic action of low doses of gamma-hydroxybutyrate in rats. Biochemical Pharmacology, 40, 2637-2640.
Kazandjian, A., Spiraki, C., Papadopoulou, Z., Sfikakis, A. and Varonos, D.D. (1988). Behavioural and biochemical effects of haloperidol during the oestrous cycle of the rat. Neuropharmacology, 27, 73-78.
Lammers, G.J., Arendts, J., Declerk, A.C., Ferrari, M.D., Schouwink, G. and Troost, J. (1993). Gammahydroxybutyrate and narcolepsy: a double-blind placebo-controlled study. Sleep, 16, 216-220.
Maitre, M. (1997). The gamma-hydroxybutyrate signalling system in brain: organization and functional implications. Progress in Neurobiology, 51, 337-361.
Martellotta, M.C., Fattore, L., Cossu, G. and Fratta, W. (1997). Rewarding properties of gamma-hydroxybutyric acid: an evaluation through place preference. Psychopharmacology, 132, 1-5.
Navarro, J.F. and Pedraza, C. (1996). An ethopharmacological assessment of the effects of gammahydroxybutyrate (GHB) on agonistic interactions in male mice. Medical Science Research, 24, 817-819.
Navarro, J.F., Manzaneque, J.M., Martín-López, M., Pedraza, C. and Dávila, G. (1996). Dose-dependent effect of gammahydroxybutyrate on catalepsy in mice. Medical Science Research, 24, 603-604.
Navarro, J.F., Manzaneque, J.M., Martín-López, M. and Vera, F. (1997). Daily versus intermittent haloperidol administration: effects on catalepsy of mice. Psicothema, 9, 83-87.
Navarro, J.F., Pedraza, C., Martín-López, M., Manzaneque, J.M., Dávila, G. and Maldonado, E. (1998). Tiapride-induced catalepsy is potentiated by gamma-hydroxybutyric acid administration. Progress in Neuropsychopharmacology & Biological Psychiatry, 22, 835-844.
Sanberg, P.R. (1980). Haloperidol-induced catalepsy is mediated by postsynaptic dopamine receptors. Nature, 284, 472-473.
Schmidt, C., Gobaille, S., Hechler, V., Schmitt, M., Bourguignon, J.J. and Maitre, M. (1991). Anti-sedative and anti-cataleptic properties of NCS-382, a gamma-hydroxybutyrate receptor antagonist. European Journal of Pharmacology, 203, 393-397.
Schmidt, C., Pain, L., Sandner, G., Gobaille, S. and Maitre, M. (1998). The anxiolytic effect of gamma-hydroxybutyrate in the elevated plus maze is reversed by the benzodiazepine receptor antagonist, flumazenil. European Journal of Pharmacology, 342, 21-27.
Snead, O.C. and Bearden, L.J. (1980). Naloxone overcomes the dopaminergic, EEG and behavioural effects of gammahydroxybutyrate. Neurology, 30, 832-838.
Tunnicliff, G. (1997). Sites of action of gamma-hydroxybutyrate (GHB). A neuroactive drug with abuse potential. Clinical Toxicology, 35, 581-590.
Van Cauter, E., Plat, L., Scharf, M.B., Leproult, R., Cespedes, S., L`Hermite, M. and Copinschi, G. (1997). Simultaneous stimulation of slow-wave sleep and growth hormone secretion by gammahydroxybutyrate in normal young men. Journal of Clinical Investigation, 100, 745-753.
Waynford, H.B. and Flecknell, P.A. (1992). Experimental and surgical technique in the rat. New York, Academic Press.
Aceptado el 20 de abril de 1999