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At least 703 records · Page 39Linked to original sources
PubMed1991

Projections of the parvocellular reticular formation to the contralateral mesencephalic trigeminal nucleus in the rat.

Projections of the parvocellular reticular nucleus (PCRt) to the contralateral mesencephalic trigeminal nucleus (Me5) were studied in the rat with neurophysiological and neuroanatomical techniques. Three types of responses (classified by latencies) were recorded extracellularly in the Me5 area after electrical stimulation of the PCRt: (1) R1 fast unitary reactions (latency 0.2-0.5 ms) found throughout the entire caudal Me5 area; (2) R2 slower unitary reactions (latency 0.7-1.2 ms) recorded ventral and lateral to the caudal Me5; and (3) R3 compound potentials (latency 1.0-2.5 ms) recorded within the ventrocaudal Me5. Relayed or synaptic fields were not observed. Intracellular recordings of identified cell bodies of periodontal afferents, muscle spindle afferents and interneurones revealed no short-term postsynaptic potentials following PCRt stimulation. In some experiments jaw muscle spindle afferent activity was increased by PCRt stimulation and jaw-opening and jaw-closing reflexes were facilitated in the contralateral musculature. Neuroanatomical experiments, using Phaseolus vulgaris leucoagglutinin as an anterograde tracer, showed direct projections with intensive collateralization of PCRt fibres into the Me5 area. Synaptic contacts of PCRt fibres with primary afferent cell bodies were observed in the ventrocaudal parts of the Me5 only. The electrophysiological results are discussed in relation to the neuroanatomical findings.

Animals↗
PubMed2005

Carbachol injections into the ventral pontine reticular formation activate locus coeruleus cells in urethane-anesthetized rats.

STUDY OBJECTIVES: Two pontine reticular regions are implicated in cholinergic triggering of rapid eye movement (REM) sleep: the dorsomedial tegmental region and the ventral nucleus pontis oralis. We previously determined that, in urethane-anesthetized rats, microinjections of a cholinergic agonist, carbachol, into the dorsal region produce REM sleep-like effects comprising cortical activation, hippocampal theta rhythm, suppression of hypoglossal (XII) nerve activity, and silencing of pontine noradrenergic neurons. Our goal was to determine whether carbachol injections into the ventral nucleus pontis oralis elicits comparable effects. DESIGN: Recording of cortical electroencephalogram, hippocampal activity, XII nerve activity, and discharge of noradrenergic cells of the locus coeruleus. SETTING: Basic neurophysiologic research laboratory. PARTICIPANTS AND INTERVENTIONS: Urethane-anesthetized, paralyzed, and artificially ventilated or nonparalyzed and spontaneously breathing rats with microinjections of carbachol (10 nL, 10 mM) into the ventral nucleus pontis oralis. MEASUREMENTS AND RESULTS: In artificially ventilated rats, carbachol injections repeatedly elicited cortical activation and hippocampal theta rhythm. Concomitantly, the activity of locus coeruleus neurons increased from 2.0 per second +/- 0.4 (SE) to 2.6 per second +/- 0.4 (P < .05, n = 8), as did XII nerve activity (by 42.5% +/- 8.8%; P < .01). In spontaneously breathing animals, carbachol similarly activated the cortical electroencephalogram and hippocampal activity, whereas XII nerve activity was reduced by 6.7% +/- 2.5% (P < .05) together with increased ventilation, as indicated by reduced end-expiratory CO2. CONCLUSION: Carbachol injections into the ventral nucleus pontis oralis activate, rather than silence, noradrenergic locus coeruleus neurons. This is not compatible with the state of REM sleep.

Anesthetics, Intravenous↗