Role of dorsal medullary reticular formation in maintenance of vasomotor tone in rats

1994 ◽  
Vol 46 (1-2) ◽  
pp. 161-169 ◽  
Author(s):  
Michael L. Korkola ◽  
Lynne C. Weaver
Keyword(s):  
Reticular Formation ◽  
Vasomotor Tone ◽  
Medullary Reticular Formation

The Involvement of Medullary Reticular Formation in the Hypotensive Effect of Extracts from Seeds of Cassia Tora

1976 ◽  
Vol 04 (04) ◽  
pp. 383-389 ◽  
Author(s):  
Samuel H. H. Chan ◽  
Anthony Koo ◽  
K. M. Li
Keyword(s):  
Blood Pressure ◽  
Reticular Formation ◽  
Hypotensive Effect ◽  
Cardiovascular Reflexes ◽  
Vasomotor Tone ◽  
Medullary Reticular Formation ◽  
Cassia Tora ◽  
Induced Hypotension ◽  
Arterial Blood

In pentobarbital anesthezied rats, the medial portion of the medullary reticular formulation has been identified to be directly involved in the hypotensive effect of extracts from the seeds of Cassia tora. This conclusion was drawn from the observed decrease in arterial blood pressure following local injection of extracts of this herb into this reticular site and from its inability to promote hypotension when the same reticular site has been electrolytically lesioned. The role of the medullary reticular formation in the Cassia tora-induced hypotension was suggested to be one which modulates the basic cardiovascular reflexes, favoring a decrease in vasomotor tone.

Effect of stimulation of the medullary reticular formation on cerebral vasomotor tonus and intracranial pressure

1987 ◽  
Vol 66 (4) ◽  
pp. 548-554 ◽  
Author(s):  
Seigo Nagao ◽  
Tsukasa Nishiura ◽  
Hideyuki Kuyama ◽  
Masakazu Suga ◽  
Takenobu Murota
Keyword(s):  
Intracranial Pressure ◽  
Reticular Formation ◽  
Cerebral Blood Volume ◽  
Systemic Arterial Pressure ◽  
Brain Swelling ◽  
Dorsomedial Nucleus ◽  
Medullary Reticular Formation ◽  
Content Type ◽  
Fine Print ◽  
Stimulation Of

✓ 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.

scholarly journals Role of the medulla oblongata in normal and high arterial blood pressure regulation: the contribution of Escola Paulista de Medicina - UNIFESP

2009 ◽  
Vol 81 (3) ◽  
pp. 589-603 ◽  
Author(s):  
Sergio L. Cravo ◽  
Ruy R. Campos ◽  
Eduardo Colombari ◽  
Mônica A. Sato ◽  
Cássia M. Bergamaschi ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Arterial Blood Pressure ◽  
Medulla Oblongata ◽  
Neural Circuits ◽  
Ventrolateral Medulla ◽  
Vasomotor Tone ◽  
Arterial Blood ◽  
Pathological Conditions ◽  
De Medicina

Several forms of experimental evidence gathered in the last 37 years have unequivocally established that the medulla oblongata harbors the main neural circuits responsible for generating the vasomotor tone and regulating arterial blood pressure. Our current understanding of this circuitry derives mainly from the studies of Pedro Guertzenstein, a former student who became Professor of Physiology at UNIFESP later, and his colleagues. In this review, we have summarized the main findings as well as our collaboration to a further understanding of the ventrolateral medulla and the control of arterial blood pressure under normal and pathological conditions.

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

1990 ◽  
Vol 63 (5) ◽  
pp. 1118-1127 ◽  
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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