Modulation of dopamine function by glycine in the nucleus accumbens of the brain of the rat.
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)
D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D004298:Dopamine / Q000502:physiology*; D005260:Female; D005998:Glycine / Q000494:pharmacology*; D008032:Limbic System / Q000502:physiology; D009043:Motor Activity / Q000502:physiology; D009714:Nucleus Accumbens / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012686:Septal Nuclei / Q000502:physiology*; D013331:Strychnine / Q000494:pharmacology
D013331:Strychnine; D005998:Glycine; D004298:Dopamine