Autonomic effector responses to stimulation of nucleus fastigius

Achari, N.K.; Downman, C. B. B.

doi:10.1113/jphysiol.1970.sp009232

Cited by 89 publications

(50 citation statements)

References 18 publications

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“…On the other hand, the magnitude of the pressor and heart rate increments elicited by the FN stimulus were apparently unaffected by the activated baroreceptors in the intact rat; in fact they were both unchanged by sinoaortic-denervarion plus vagotomy. These observations confirm previous reports in cats (Achari and Downman, 1970;Lisander and Martner, 1971) and, for the suppression of the cardiovagal reflex by stimulation of FN, also in rats (Del Bo et al, 1983b). Since we have recently observed (Del Bo et al, 1982) that projections from the fastigial pressor area in rats terminate limitedly on selective neuronal groups in the pons and medulla, the dissociation of the effects produced by the interaction of FN stimulation and baroreceptor reflexes on VP secretion and those on AP and HR would suggest more than one relay nuclei controlling the cardiovascular and VP effects elicited by stimulation of the FN.…”

Section: Discussionsupporting

confidence: 93%

Inhibitory influences from arterial baroreceptors on vasopressin release elicited by fastigial stimulation in rats.

Bo¹,

Sved²,

Reis³

1984

Circulation Research

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SUMMARY. Electrical stimulation of the fastigial nucleus in anesthetized, paralyzed, and artificially ventilated rats for 10 seconds (50 Hz) induced a stimulus-locked elevation of arterial pressure (the fastigial pressor response) and increased plasma vasopressin. Cervical spinal cord transection abolished the stimulus-locked fastigial pressor response and augmented the vasopressin response to a 10-fold increase (19 ± 1 to 188 ± 58 pg/ml, P < 0.05; n = 8). Grading the pressor elevations occurring during the fastigial nucleus stimulus changed the amounts of vasopressin released in the same animal: acute adrenalectomy and chemosympathectomy by guanethidine reduced the magnitude of the fastigial pressor response and facilitated the vasopressin release to fastigial nucleus stimulation (intact:-52 ± 1 1 pg/ml; after adrenalectomy and chemosympathectomy, 254 ± 73 pg/ml, P < 0.05, n = 6). Subsequent intravenous administration of a bolus of phenylephrine to increase mean arterial pressure during fastigial nucleus stimulus, as in intact situation, reduced the vasopressin release (47 ± 9 pg/ml). After sinoaortic denervation plus vagotomy, the fastigial pressor response was preserved; however, vasopressin still increased 11-fold (from 11 ± 1 to 126 ± 23 pg/ml, P < 0.01, n = 8). Vagotomy alone did not affect the vasopressin resting level nor the 4-fold increase in response to fastigial nucleus stimulation. Therefore, stimulus-locked elevations of arterial pressure oppose, by reflex mechanisms mediated through baroreceptors, but do not prevent the release of vasopressin elicited by stimulation of the fastigial nucleus. (Circ Res 54: 248-253, 1984) ELECTRICAL stimulation of rostromedial portion of the cerebellar fastigial nucleus (FN) in rats, as in other species, elevates heart rate (HR) and arterial pressure (AP), the so-called fastigial pressor response (FPR) (Miura and Reis, 1969). Recently, we have observed that FN stimulation will also release vasopressin (VP) into the circulation (Del Bo et al., 1983a). In the intact rat, stimulation of FN increased plasma VP approximately 3-fold, an elevation which appeared to have little, if any, pressor effect. However, if the rise of AP produced by FN stimulation was blocked either by transection of the spinal cord at the first cervical segment or by chemosympathectomy plus adrenalectomy, FN stimulation elicited an increase in plasma VP sufficient to cause a delayed and prolonged elevation in AP (Del Bo et al., 1983a). The mechanism which accounts for the facilitated release of VP after blockade of FPR is unknown. However, since activation of arterial baroreceptors will inhibit the release of VP (Share, 1974), it is conceivable that the elevation of AP produced by FN stimulation feeds back, via baroreceptors, to inhibit the release of VP produced by the same stimulus. The following study was designed to investigate this hypothesis. MethodsThe methods for preparation of animals and stimulation of cerebellum are described in detail elsewhere (Del Bo et al., 1983a) and will only be...

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Section: Discussionsupporting

confidence: 93%

Inhibitory influences from arterial baroreceptors on vasopressin release elicited by fastigial stimulation in rats.

Bo¹,

Sved²,

Reis³

1984

Circulation Research

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“…This pressor response is mediated by direct fastigiobulbar projections carried by the juxtarestiform body to a pressor zone in the paramedian reticular formation (Wang, 1981). These projections are indicated by the fact that the FPR can be abolished by lesions of the paramedian reticular nucleus or by sections of the juxtarestiform body (Miura & Reis, 1970) but is not affected by precollicular decerebration (Achari & Downman, 1970) or by transect ions of the middle or superior cerebellar peduncles (Miura & Reis, 1970. Inputs from the fastigial nucleus and carotid baroreceptors exert antagonistic influences on individual neurons within the reticular formation pressor zone and thereby modulate cardiovascular tone (Miura & Reis, 1970).…”

Section: Fastigiobulbar Pathways and The Integration Of Autonomic Andmentioning

confidence: 99%

The paleocerebellum and the integration of behavioral function

1982

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The role of the cerebellum in motor function is well documented. Additional data clearly im· plicate the cerebellum in the regulation of sensory processes and autonomic functions, and more recent findings establish an influence of cerebellar systems on the regulation of emotional and motivational behaviors. The cerebellum provides extensive projections to brain· stem and limbic mechanisms that have been implicated in behavioral regulation, and experimen· tal manipulations of the cerebellum have been found to profoundly affect behavioral processes. In the present paper, w~ review some of these findings and offer a conceptual view of cerebellar function that reconciles these apparently disparate actions. We suggest that the cerebellum exerts functionally similar influences at all levels of sensorimotor and behavioral orga· nization. This model provides a conceptual framework for understanding the behavioral consequences of cerebellar dysfunctions, which we suggest can be viewed as behavioral parallels to the classical cerebellar motor syndromes. Data implicating cerebellar systems in the pathogenesis of developmental disturbances in behavioral processes are also considered in the con· text of the present conception of cerebellar·behavioral function.

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“…It has recently been discovered (9-11) that electrical stimulation of a highly restricted region of one of the deep nuclei of the cerebellum, the fastigial nucleus, can elicit a powerful activation of the cardiovascular system. The cardiovascular events associated with the fastigial pressor response consist of an elevation in systemic arterial blood pressures, tachycardia, and vasoconstriction of arteries in limbs, kidney, and abdominal viscera (11)(12)(13)(14); this cardiodynamic pattern simulates the orthostatic reflex. On this basis we have suggested (14) that the cerebellum may participate in the regulation of orthostatic mechanisms.…”

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Role of the Cerebellum and the Vestibular Apparatus in Regulation of Orthostatic Reflexes in the Cat

Doba

Reis

1974

Circulation Research

133

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The contribution of the fastigial nucleus and the vestibular nerves (eighth cranial nerves) to the orthostatic reflexes in anesthetized, paralyzed cats was studied. Bilateral lesions of the rostral fastigial nucleus resulted in impairment of the reflex changes in blood pressure, femoral arterial flow, and resistance evoked by head-up tilting to 30° or 60°. The deficit consisted of an increase in the magnitude of the initial fall in blood pressure during tilting. The effects on blood pressure were paralleled by decreased vasoconstriction in the femoral artery. Extracranial lesions of the vestibular nerves produced comparable deficits which were not enhanced by subsequent lesions of the fastigial nucleus. Denervation of the baroreceptors impaired the reflexes, and subsequent lesion of the fastigial nucleus increased this deficit. The pressor response evoked by electrical stimulation of the rostral fastigial nucleus also reversed the deficit in orthostasis produced by hemorrhage. Small doses of sodium pentobarbital which did not alter the resting blood pressure or the pressor response to carotid occlusion impaired the responses to stimulation of the fastigial nucleus and tilting. Therefore, the rostral fastigial nucleus, which might be triggered by the vestibular apparatus, appears to participate in concert with the baroreceptors in the initiation and possibly the maintenance of the orthostatic reflexes. KEY WORDSsympathetic nervous system blood pressure posture cerebellar nuclei blood flow brain stimulation baroreceptor reflexes• The orthostatic reflexes consist of a patterned activation of sympathetic neurons in response to the assumption of an upright posture (1). The preponderant effect is a widespread vasoconstriction of resistance and capacitance vessels and tachycardia (1, 2-). The vasoconstriction tends to resist the hydrodynamic action of gravity which forces the blood into the dependent extremities and viscera; the response thereby maintains blood pressure and protects circulation to the brain. It is widely assumed that the orthostatic responses are triggered by baroreceptors, particularly those in the carotid sinus (1, 3) and possibly those in the low-pressure circulation (4-6). According to this view, the reduction in stretch of the sinus during standing results in a decrease in discharge from the baroreceptors, a release of preganglionic sympathetic neurons from inhibition, and thus an increase in sympathetic nerve activation and vasoconstriction. There are, however, several studies (7,8) in which deafferentation of

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Autonomic effector responses to stimulation of nucleus fastigius

Cited by 89 publications

References 18 publications

Inhibitory influences from arterial baroreceptors on vasopressin release elicited by fastigial stimulation in rats.

Inhibitory influences from arterial baroreceptors on vasopressin release elicited by fastigial stimulation in rats.

The paleocerebellum and the integration of behavioral function

Role of the Cerebellum and the Vestibular Apparatus in Regulation of Orthostatic Reflexes in the Cat

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