To elucidate the mechanism of psychostimulant-induced reverse tolerance [A. Kifune, S. Tadokoro, Modification of stereotypy-producing and ambulation-increasing effects following repeated administration of methamphetamine in rats, Jpn. J. Psychopharmacol. 11 (1991) 207–214 [11]; N.J. Leith, R. Kuczenski, Chronic amphetamine: tolerance and reverse tolerance reflect different behavioral actions of the dog, Pharmacol. Biochem. Behav. 15 (1981) 399–405 [13]; S. Tadokoro, H. Kuribara, Reverse tolerance to the ambulation-increasing effect of methamphetamine in mice as an animal model of amphetamine-psychosis, Psychopharmacol. Bull. 22 (1986) 757–762 [18]; S. Tadokoro, H. Kuribara, Modification of the behavioral effects of drugs after repeated administration: special reference to the reverse tolerance, Folia Pharmacologica Japonica 95 (1990) 229–238 [19]], the effects of lithium on ambulatory activity [P. Cappeliez, E. Moore, Effects of lithium on an amphetamine animal model of bipolar disorder, Prog. Neuro-Psychopharmacol. Biol. Psychiatry 14 (1990) 347–358 [1]; M. Hirabayashi, M.K. Alam, Enhancing effect of methamphetamine on ambulatory activity produced by repeated administration on mice, Pharmacol. Biochem. Behav. 15 (1981) 925–932 [7]; M. Hirabayashi, S. Okada, S. Tadokoro, Comparison of sensitization to ambulation-increasing effects of cocaine and methamphetamine after repeated administration in mice, J. Pharm. Pharmacol. 43 (1991) 827–830 [8]; T. Miyauchi, K. Kikuchi, S. Satoh, Further studies on the potentiating effect of lithium chloride on methamphetamine-induced stereotypy in mice, Jpn. J. Pharmacol. 31 (1981) 61–68 [14]; H. Ozawa, T. Nozu, H. Aihara, F. Akiyama, M. Sasajima, Pharmacokinetics and general pharmacological actions of lithium salts administered singly or repeatedly, Folia Pharmacologica Japonica 72 (1976) 433–443 [15].] and cerebral c-Fos expression [S. Ceccatelli, M.J. Villar, M. Goldstein, T. Hokfelt, Expression of c-Fos immunoreactivity in transmitter-characterized neurons after stress, Proc. Natl. Acad. Sci. USA 86 (1989) 9569–9573 [2]; L. Giovannelli, P.J. Shiromani, G.F. Jirikoski, F.E. Bloom, Expression of c-fos protein by immunohistochemically identified oxytocin neurons in the rat hypothalamus upon osmotic stimulation, Brain Research 588 (1992) 41–48 [4]; B.T. Hope, H.E. Nye, M.B. Kelz, D.W. Self, M.J. Iadarola, Y. Nakabeppu, R.S. Duman, E.J. Nestler, Induction of a long-lasting AP-1 complex composed of altered Fos-like proteins in brain by chronic cocaine and other chronic treatments, Neuron 13 (1994) 1235–1244 [10]; T. Miyauchi, K. Kikuchi, S. Satoh, Further studies on the potentiating effect of lithium chloride on methamphetamine-induced stereotypy in mice, Jpn. J. Pharmacol. 31 (1981) 61–68 [14]; F.R. Sharp, S.M. Sager, K. Hicks, D. Lowenstein, K. Hisanaga, c-fos mRNA, Fos, and Fos-related antigen induction by hypertonic saline and stress, J. Neurosci. 11 (1991) 2321–2331 [16].] were investigated in mice injected with methamphetamine (2 mg/kg, s.c., one to five times). The ambulatory activity enhanced by either acute or chronic methamphetamine injection was delayed or diminished by lithium chloride (LiCl) pretreatment [R.G. Fessler, R.D. Sturgeon, S.F. London, H.Y. Meltzer, Effects of lithium on behaviour induced by phencyclidine and amphetamine in rats, Psychopharmacology 78 (1982) 373–376 [3].]. How the Li-sensitive c-Fos expression in the dorsolateral geniculate nucleus and striatum is related to methamphetamine-induced behavioral excitation is unclear. This protocol, in combination with c-Fos expression of mouse cerebral regions, may provide a useful tool for quantitation of ambulatory activity during c-Fos expression. Themes: Neural basis of behavior Topics: Psychopharmacological agents