Dorsomedial pontine neurons with descending projections to the medullary reticular formation express orexin-1 and adrenergic α2A receptor mRNA

✓ The authors report the results of a study to evaluate the effect of stimulation of the medullary reticular formation on cerebral vasomotor tonus and intracranial pressure (ICP) after the hypothalamic dorsomedial nucleus and midbrain reticular formation were destroyed. Systemic arterial pressure (BP), ICP, and local cerebral blood volume (CBV) were continuously recorded in 32 cats. To assess the changes in the cerebral vasomotor tonus, the vasomotor index defined by the increase in ICP per unit change in BP was calculated. In 29 of the 32 animals, BP, ICP, and CBV increased simultaneously immediately after stimulation. The increase in ICP was not secondary to the increase in BP, because the vasomotor index during stimulation was significantly higher than the vasomotor index after administration of angiotensin II. The vasomotor index was high during stimulation of the area around the nucleus reticularis parvocellularis. In animals with the spinal cord transected at the C-2 vertebral level, ICP increased without a change in BP. These findings indicate that the areas stimulated in the medullary reticular formation play an important role in decreasing cerebral vasomotor tonus. This effect was not influenced by bilateral superior cervical ganglionectomy, indicating that there is an intrinsic neural pathway that regulates cerebral vasomotor tonus directly. In three animals, marked biphasic or progressive increases in ICP up to 100 mm Hg were evoked by stimulation. The reduction of cerebral vasomotor tonus and concomitant vasopressor response induced by stimulation of the medullary reticular formation may be one of the causes of acute brain swelling.

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Convergence of heterotopic nociceptive information onto neurons of caudal medullary reticular formation in monkey (Macaca fascicularis)

Journal of Neurophysiology ◽

10.1152/jn.1990.63.5.1118 ◽

1990 ◽

Vol 63 (5) ◽

pp. 1118-1127 ◽

Cited By ~ 44

Author(s):

L. Villanueva ◽

K. D. Cliffer ◽

L. S. Sorkin ◽

D. Le Bars ◽

W. D. Willis

Keyword(s):

Electrical Stimulation ◽

Reticular Formation ◽

Mechanical Stimulation ◽

Background Activity ◽

The Body ◽

Thermal Stimulation ◽

Medullary Reticular Formation ◽

Nociceptive Information ◽

Noxious Mechanical Stimulation ◽

Stimulation Of

1. Recordings were made in anesthetized monkeys from neurons in the medullary reticular formation (MRF) caudal to the obex. Responses of 19 MRF neurons to mechanical, thermal, and/or electrical stimulation were examined. MRF neurons exhibited convergence of nociceptive cutaneous inputs from widespread areas of the body and face. 2. MRF neurons exhibited low levels of background activity. Background activity increased after periods of intense cutaneous mechanical or thermal stimulation. Nearly all MRF neurons tested failed to respond to heterosensory stimuli (flashes, whistle sounds), and none responded to joint movements. 3. MRF neurons were excited by and encoded the intensity of noxious mechanical stimulation. Responses to stimuli on contralateral limbs were greater than those to stimuli on ipsilateral limbs. Responses were greater to stimuli on the forelimbs than to stimuli on the hindlimbs. 4. MRF neurons responded to noxious thermal stimulation (51 degrees C) of widespread areas of the body. Mean responses from stimulation at different locations were generally parallel to those for noxious mechanical stimulation. Responses increased with intensity of noxious thermal stimulation (45-50 degrees C). 5. MRF neurons responded with one or two peaks of activation to percutaneous electrical stimulation applied to the limbs, the face, or the tail. The differences in latency of responses to stimulating two locations along the tail suggested that activity was elicited by activation of peripheral fibers with a mean conduction velocity in the A delta range. Stimulation of the contralateral hindlimb elicited greater responses, with lower thresholds and shorter latencies, than did stimulation of the ipsilateral hindlimb. 6. Electrophysiological properties of monkey MRF neurons resembled those of neurons in the medullary subnucleus reticularis dorsalis (SRD) in the rat. Neurons in the caudal medullary reticular formation could play a role in processing nociceptive information. Convergence of nociceptive cutaneous input from widespread areas of the body suggests that MRF neurons may contribute to autonomic, affective, attentional, and/or sensory-motor processes related to pain.

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Calcium-induced calcium release activates spontaneous miniature outward currents in newt medullary reticular formation neurons

Journal of Neurophysiology ◽

10.1152/jn.00616.2017 ◽

2018 ◽

Vol 120 (6) ◽

pp. 3140-3154 ◽

Cited By ~ 2

Author(s):

Daniel B. Yaeger ◽

Emma J. Coddington

Keyword(s):

Action Potential ◽

Reticular Formation ◽

Calcium Release ◽

Motor Behavior ◽

Brain Slices ◽

Medullary Reticular Formation ◽

Outward Currents ◽

Decay Times ◽

Action Potential Threshold ◽

Potential Threshold

Neurons in the medullary reticular formation are involved in the control of postural and locomotor behaviors in all vertebrates. Reticulospinal neurons in this brain region provide one of the major descending projections to the spinal cord. Although neurons in the newt medullary reticular formation have been extensively studied using in vivo extracellular recordings, little is known of their intrinsic biophysical properties or of the underlying circuitry of this region. Using whole cell patch-clamp recordings in brain slices containing the rostromedial reticular formation from adult male newts, we observed spontaneous miniature outward currents (SMOCs) in ~2/3 of neurons. Although SMOCs superficially resembled inhibitory postsynaptic currents (IPSCs), they had slower risetimes and decay times than spontaneous IPSCs. SMOCs required intracellular Ca2+ release from ryanodine receptors and were also dependent on the influx of extracellular Ca2+. SMOCs were unaffected by apamin but were partially blocked by iberiotoxin and charybdotoxin, indicating that SMOCs were mediated by big-conductance Ca2+-activated K+ channels. Application of the sarco/endoplasmic Ca2+ ATPase inhibitor cyclopiazonic acid blocked the generation of SMOCs and also increased neural excitability. Neurons with SMOCs had significantly broader action potentials, slower membrane time constants, and higher input resistance than neurons without SMOCs. Thus, SMOCs may serve as a mechanism to regulate action potential threshold in a majority of neurons within the newt medullary reticular formation. NEW & NOTEWORTHY The medullary reticular formation exerts a powerful influence on sensorimotor integration and subsequent motor behavior, yet little is known about the neurons involved. In this study, we identify a transient potassium current that regulates action potential threshold in a majority of medullary reticular neurons.

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Cerebellar control of input-output coupling within vestibulospinal reflexes: role of the lateral vestibular nucleus and of the medullary reticular formation.

Frontiers in Neuroscience ◽

10.3389/conf.fnins.2010.83.00013 ◽

2010 ◽

Vol 4 ◽

Author(s):

Manzoni Diego

Keyword(s):

Reticular Formation ◽

Vestibular Nucleus ◽

Output Coupling ◽

Lateral Vestibular Nucleus ◽

Input Output ◽

Medullary Reticular Formation ◽

Vestibulospinal Reflexes

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Responses of the rat medullary reticular formation neurons to electrical stimulation of the sciatic nerve and mechanical nociceptive stimulation of the skin

PAIN RESEARCH ◽

10.11154/pain.18.127 ◽

2003 ◽

Vol 18 (3) ◽

pp. 127-136

Author(s):

Risa Watanabe ◽

Taiko Kitamura ◽

Jinzo Yamada

Keyword(s):

Electrical Stimulation ◽

Sciatic Nerve ◽

Reticular Formation ◽

Nociceptive Stimulation ◽

Medullary Reticular Formation ◽

Stimulation Of

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Acute brain swelling and edema by stimulation of the medullary reticular formation in the cold injured brain

Okayama Igakkai Zasshi (Journal of Okayama Medical Association) ◽

10.4044/joma1947.101.7-8_743 ◽

1989 ◽

Vol 101 (7-8) ◽

pp. 743-762

Author(s):

Masamitsu KAWACHI

Keyword(s):

Reticular Formation ◽

Brain Swelling ◽

Medullary Reticular Formation ◽

Injured Brain ◽

Stimulation Of

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Global Cerebral Vasodilatation Elicited by Focal Electrical Stimulation within the Dorsal Medullary Reticular Formation in Anesthetized Rat

Journal of Cerebral Blood Flow & Metabolism ◽

10.1038/jcbfm.1983.41 ◽

1983 ◽

Vol 3 (3) ◽

pp. 270-279 ◽

Cited By ~ 34

Author(s):

Costantino Iadecola ◽

Masatsugu Nakai ◽

Ehud Arbit ◽

Donald J. Reis

Keyword(s):

Electrical Stimulation ◽

Reticular Formation ◽

Medial Longitudinal Fasciculus ◽

Medullary Reticular Formation ◽

Tissue Samples ◽

The Central Nervous System ◽

Cerebral Vasodilatation ◽

Cervical Sympathetic ◽

Global Increase ◽

Stimulation Of

We examined the effects of electrical stimulation of a restricted area of the dorsal medullary reticular formation (DMRF) on regional cerebral blood flow (CBF) in anesthetized (by chloralose), paralyzed (by curare) rats. CBF was measured in tissue samples by the Kety principle, with 14C-iodoantipyrine as indicator. Stimulation of DMRF elicited a widespread, significant increase in CBF in 12 of 13 areas. The increase in flow was greatest in cerebral cortex, up to 240% of control. However, it was also substantially increased in selected regions of telencephalon, diencephalon, mesencephalon, and lower brainstem, but not cerebellum. In contrast, electrical stimulation of the midline (interstitial nucleus of the medial longitudinal fasciculus) 1 mm medial to the DMRF did not change CBF. The increase in CBF evoked by DMRF stimulation persisted after transection of the spinal cord at C1 or cervical sympathetic trunk. We conclude that excitation of neurons originating in or passing through the DMRF can elicit a potent and virtually global increase of CBF. The effect appears to be mediated by intrinsic pathways of the central nervous system.

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