Barnes J C, Costall B, Naylor R J
Neuropharmacology. 1986 Dec;25(12):1347-51. doi: 10.1016/0028-3908(86)90107-3.
The effects of glycine on the phasic changes in locomotor activity in the rat, caused by a persistent infusion of dopamine (DA) into the nucleus accumbens (ACB) were investigated. Dopamine (25 micrograms/24 hr), infused into the nucleus accumbens for 13 days, caused hyperactivity, with two peaks occurring on days 3-4 and 9-11. Glycine (12.5 or 25 micrograms/24 hr) infused into the nucleus accumbens on its own did not alter the locomotor activity, yet when infused at the same time as DA (25 micrograms/24 hr), glycine (12.5 or 25 micrograms/24 hr) inhibited the development of the first peak of hyperactivity induced by DA, with no effect on the second peak. A larger dose of glycine (50 micrograms/24 hr), infused alone, significantly increased locomotor activity, and a combination of this dose with DA (25 micrograms/24 hr), led to a temporal shift in the response to DA such that the first peak of hyperactivity was delayed to "fuse" with the second peak. The locomotor response to a threshold dose of DA (6.25 micrograms/24 hr) plus glycine (50 micrograms/24 hr) was no greater than could be accounted for by the hyperactivity response to glycine alone (50 micrograms/24 hr). Strychnine (10 micrograms/24 hr), infused into the nucleus accumbens, produced no alteration in locomotor activity. Similarly, when infused together with DA (25 micrograms/24 hr), strychnine (10 micrograms/24 hr) caused no significant alteration in the phasic hyperactivity induced by DA. However, strychnine (10 micrograms/24 hr), infused together with DA and glycine (25 and 12.5 micrograms/24 hr respectively), prevented the inhibition by glycine of the first peak of hyperactivity induced by DA.(ABSTRACT TRUNCATED AT 250 WORDS)
