Serotonergic activation of locomotor behavior and posture in one-day old rats

Abstract

The purpose of this study was to determine what dose of quipazine, a serotonergic agonist, facilitates air-stepping and induces postural control and patterns of locomotion in newborn rats. Subjects in both experiments were 1-day-old rat pups. In Experiment 1, pups were restrained and tested for air-stepping in a 35-min test session. Immediately following a 5-min baseline, pups were treated with quipazine (1.0, 3.0, or 10.0 mg/kg) or saline (vehicle control), administered intraperitoneally in a 50 microliter injection. Bilateral alternating stepping occurred most frequently following treatment with 10.0 mg/kg quipazine, however the percentage of alternating steps, interlimb phase, and step period were very similar between the 3.0 and 10.0 mg/kg doses. For interlimb phase, the forelimbs and hindlimbs maintained a near perfect anti-phase pattern of coordination, with step period averaging about 1 second. In Experiment 2, pups were treated with 3.0 or 10.0 mg/kg quipazine or saline, and then were placed on a surface (open field, unrestrained). Both doses of quipazine resulted in developmentally advanced postural control and locomotor patterns, including head elevation, postural stances, pivoting, crawling, and a few instances of quadrupedal walking. The 3.0 mg/kg dose of quipazine was the most effective at evoking sustained locomotion. Between the 2 experiments, behavior exhibited by the rat pup varied based on testing environment, emphasizing the role that environment and sensory cues exert over motor behavior. Overall, quipazine administered at a dose of 3.0 mg/kg was highly effective at promoting alternating limb coordination and inducing locomotor activity in both testing environments.

Dihydroergotamine affects spatial behavior and neurotransmission in the central nervous system of Wistar rats

“…Noradrenaline released by sympathetic nerve fibres and noradrenergic nuclei support the activation and control of spinal motor output. Swann et al [47] demonstrated that the administration of quipazine, a serotonin receptor agonist, improved movement and body posture in independently moving newborn rat. Sławińska et al [48] also showed that the administration of serotonin receptor agonists increases the agility of the hind limbs in rats with paraplegia of the hind limbs.…”

Multilevel Analysis of Locomotion in Immature Preparations Suggests Innovative Strategies to Reactivate Stepping after Spinal Cord Injury

“…For example, when newborn rats are suspended in a sling, airstepping may be evoked by treatment with the dopamine precursor L -DOPA [184] or the 5-HT 2A receptor agonist quipazine [185]. Both L -DOPA-induced and quipazine-induced air-stepping produce alternating limb kinematic patterns consistent with walking locomotion [186,187]. A mid-or low-thoracic spinal transection eliminates L -DOPA-induced hindlimb stepping [188], however it does not eliminate quipazine-induced stepping [120,121,188,189], suggesting that 5-HT receptors in the spinal cord engage spinal Fig.…”

“…locomotor networks. Pharmacological stimulation of air-stepping has led to better understanding of the development [120,190,191], mechanisms [188,192], function [187], and sensory modulation [121,185] of locomotor circuits in vivo, including for animals with SCI [119,189,193,194].…”

“…While the spinal in vivo neonatal rat preparation is more directly relevant to SCI, the intact neonatal rat offers important insights into general issues of neurobehavioral development and plasticity as well. For example, it has been shown that locomotor behavior in intact newborn rats is modulated by the substrate that the animal is stepping on [188], ROM restriction [191], treadmill speed [215], posture [216], and testing environment [187]. Thus even before the onset of independent walking and maturation of neural pathways (e.g., corticospinal tract development, myelination), it is clear that locomotor mechanisms demonstrate plasticity and are responsive to the environment.…”

Perinatal effects of scorpion venoms: maternal and offspring development

“…The evolution of the locomotion, from pregnancy until adolescence, does not involve a single system, but it depends on a variety of systems, such as the sensory, motor, and postural systems and neurotransmitters [ 62 ]. During the long period of neural maturation there are critical periods that are subject to internal and external influences, inducing various behavioral effects [ 63 ].…”