Modulation of locomotor activity by multiple 5-HT and dopaminergic receptor subtypes in the neonatal mouse spinal cord.
Recently, it has been shown that bath-applied 5-HT can elicit fictive locomotion from perinatal mouse preparations. Since 5-HT acts on multiple receptor subtypes, the focus of this study was to examine which receptor families contribute to the genesis and modulation of locomotor activity. Blockade of 5-HT(2) (ketanserin or N-desmethylclozapine) or 5-HT(7) receptors (SB-269970) could reversibly block or modulate the locomotor-like pattern. A 5-HT(2) agonist (alpha-methyl-5-HT) was shown to be capable of activating the rhythm. Bath application of 5-HT(7) agonists (5-CT) generally led to a tonic increase in neurogram discharge, accompanied by bouts of rhythmic activity. Blockade of dopaminergic receptors (D(1) [R-(+)-SCH-23390 or LE 300]/D(2) [(+/-)-sulpiride or L-741,626] ) could reversibly disrupt the rhythm and most effectively did so when the D(1) and D(2) antagonists were added together. Conversely, 5-HT(2) and D(1)/D(2) agonists can interact to evoke locomotor activity. Overall, our data show that, in the neonatal mouse preparation, 5-HT evoked locomotion is partly dependent on activation of 5-HT(2), 5-HT(7), and dopaminergic receptor subtypes.
Madriaga
M A
MA
Department of Physiology and Biophysics, Calgary Brain Institute, 3330 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada.
McPhee
L C
LC
Chersa
T
T
Christie
K J
KJ
Whelan
P J
PJ
D000818:Animals; D000831:Animals, Newborn; D015259:Dopamine Agents / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D051379:Mice; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology*; D011954:Receptors, Dopamine / Q000145:classification / Q000502:physiology*; D011985:Receptors, Serotonin / Q000145:classification / Q000502:physiology*; D018490:Serotonin Agents / Q000494:pharmacology; D013116:Spinal Cord / Q000187:drug effects / Q000502:physiology*
D015259:Dopamine Agents; D011954:Receptors, Dopamine; D011985:Receptors, Serotonin; D018490:Serotonin Agents