Glutamate and picrotoxin injections into the preoptic basal forebrain initiate locomotion in the anesthetized rat.
This study determined the locomotor effects of glutamate and picrotoxin injections and electrical stimulation in the preoptic basal forebrain. Male rats, anesthetized with Nembutal, were held in a stereotaxic apparatus such that stepping rotated a wheel. Cathodal stimulation (0.5-ms pulses, 50-Hz frequency, 10-s train, less than 100 microA) was applied through a 30-gauge stainless-steel, insulated cannula to find locomotor sites. Glutamate (20 mM or 2 M) or picrotoxin (100 or 200 ng) were injected in volumes of 0.2 or 0.1 microliter of saline at a rate of 1 microliter/5 min. Electrical stimulation elicited locomotion (principally hindlimbs) in 32 sites which included the lateral and medial preoptic areas and the bed nucleus of the stria terminalis (BST). Stimulation in 23 sites, most in the BST and septal area, failed to produce locomotion. Stepping was elicited by glutamate and electrical stimulation in 15 sites. Glutamate was ineffective at 21 sites, at 6 of these sites electrical stimulation was effective. Longer bouts of locomotion were produced by 20 nM glutamate. Picrotoxin produced more intense and prolonged locomotion than glutamate. It was effective in 15 sites, at 12 of which electrical stimulation was also effective. At some ventral sites, picrotoxin-elicited stepping was continuous, at others it appeared in bursts of 5-20 s duration. At dorsal sites, the locomotor bursts were punctuated by episodes of pelvic flexion. Picrotoxin was ineffective at 12 sites, 7 of which were effective with electrical stimulation. These results indicate that activity of neurons in the preoptic basal forebrain can initiate locomotion.
D000758:Anesthesia; D000818:Animals; D004558:Electric Stimulation; D005971:Glutamates / Q000008:administration & dosage / Q000494:pharmacology*; D018698:Glutamic Acid; D007267:Injections; D008124:Locomotion / Q000187:drug effects; D008297:Male; D010852:Picrotoxin / Q000008:administration & dosage / Q000494:pharmacology*; D011301:Preoptic Area / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains
D005971:Glutamates; D018698:Glutamic Acid; D010852:Picrotoxin