Corticoliberin activity of rat neurohypophysis is distinct from vasopressin

1981 ◽  
Vol 240 (6) ◽  
pp. E689-E693 ◽  
Author(s):  
M. Karteszi ◽  
E. Stark ◽  
G. Rappay ◽  
F. A. Laszlo ◽  
G. B. Makara
Keyword(s):  
Electrical Stimulation ◽  
Median Eminence ◽  
Brattleboro Rats ◽  
Neural Lobe ◽  
Experimental Conditions ◽  
Adrenal Axis ◽  
Corticosterone Secretion ◽  
Pituitary Adrenal Axis ◽  
Stimulation Of

Electrical stimulation of the neural lobe of the pituitary resulted in an increase of corticosterone secretion in both normal and Brattleboro rats. Bioassaying the corticoliberin (CRF) activity of stalk-median eminence and neural lobe extracts obtained from normal and Brattleboro rats revealed that the endogenous vasopressin was not a prerequisite of ACTH-releasing potency. Arginine-8-vasopressin failed to potentiate the CRF activity of the different extracts. These data suggest that a nonvasopressin substance(s) with CRF activity can be released from the neurohypophysis of the rat, and it may contribute to activating the pituitary-adrenal axis under certain experimental conditions.

ADENOHYPOPHYSEAL LH CONTENT IN NORMAL, ANDROGEN-STERILIZED AND PROGESTERONE-PRIMED STERILE FEMALE RATS

1962 ◽  
Vol 39 (1) ◽  
pp. 13-21 ◽  
Author(s):  
Roger A. Gorski ◽  
Charles A. Barraclough
Keyword(s):  
Ascorbic Acid ◽  
Electrical Stimulation ◽  
Quantitative Determination ◽  
Median Eminence ◽  
Hypothalamic Stimulation ◽  
Female Rats ◽  
Rat Pituitary ◽  
Gland Content ◽  
Stimulation Of

ABSTRACT We have previously suggested that the failure of the androgen-sterilized, persistent-oestrous rat to ovulate, following electrical stimulation of the median eminence structures of the hypothalamus, is due to an insufficiency in adenohypophyseal LH concentration. Using the ovarian ascorbic acid technique for quantitative determination of pituitary LH content, the present studies have demonstrated that the sterile rat pituitary gland contains one-third the LH content of the normal prooestrous gland. Furthermore, not only does progesterone priming of this persistent-oestrous rat result in a 75 % increase in LH concentration, but on hypothalamic stimulation sufficient LH is released to induce ovulation. The decrease in LH concentration which accompanies ovulation in the progesterone-primed, sterile rat is approximately 45 % of the total gland content as compared with a 51 % decrease in pituitary content in the normal cyclic rat.

Reflex Inhibition of Normal Cramp Following Electrical Stimulation of the Muscle Tendon

2007 ◽  
Vol 98 (3) ◽  
pp. 1102-1107 ◽  
Author(s):  
Serajul I. Khan ◽  
John A. Burne
Keyword(s):  
Electrical Stimulation ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Muscle Cramp ◽  
Emg Activity ◽  
Reflex Inhibition ◽  
Experimental Conditions ◽  
Inhibitory Feedback ◽  
Two Phases ◽  
Stimulation Of

Muscle cramp was induced in one head of the gastrocnemius muscle (GA) in eight of thirteen subjects using maximum voluntary contraction when the muscle was in the shortened position. Cramp in GA was painful, involuntary, and localized. Induction of cramp was indicated by the presence of electromyographic (EMG) activity in one head of GA while the other head remained silent. In all cramping subjects, reflex inhibition of cramp electrical activity was observed following Achilles tendon electrical stimulation and they all reported subjective relief of cramp. Thus muscle cramp can be inhibited by stimulation of tendon afferents in the cramped muscle. When the inhibition of cramp-generated EMG and voluntary EMG was compared at similar mean EMG levels, the area and timing of the two phases of inhibition (I1, I2) did not differ significantly. This strongly suggests that the same reflex pathway was the source of the inhibition in both cases. Thus the cramp-generated EMG is also likely to be driven by spinal synaptic input to the motorneurons. We have found that the muscle conditions that appear necessary to facilitate cramp, a near to maximal contraction of the shortened muscle, are also the conditions that render the inhibition generated by tendon afferents ineffective. When the strength of tendon inhibition in cramping subjects was compared with that in subjects that failed to cramp, it was found to be significantly weaker under the same experimental conditions. It is likely that reduced inhibitory feedback from tendon afferents has an important role in generating cramp.

Avoidance and approach learning motivated by stimulation of identical hypothalamic loci

1959 ◽  
Vol 197 (1) ◽  
pp. 153-157 ◽  
Author(s):  
George W. Brown ◽  
Bertram D. Cohen
Keyword(s):  
Electrical Stimulation ◽  
Lateral Hypothalamus ◽  
Opportunity To Learn ◽  
Hypothalamic Stimulation ◽  
Experimental Conditions ◽  
Approach Response ◽  
Lateral Hypothalamic ◽  
Stimulating Electrodes ◽  
Second Procedure ◽  
Stimulation Of

Cats with stimulating electrodes implanted in the lateral hypothalamus were subjected to two types of experimental procedures. In the first procedure the cats were given an opportunity to learn to avoid hypothalamic stimulation which produces a typical ‘hypothalamic rage’ response. The second procedure allows the same cats to learn to approach an area where the hypothalamic stimulus is administered. In both procedures, electrical stimulation was delivered through identical electrodes, yet each animal learned the appropriate avoidance or approach response, depending upon the experimental conditions. Therefore, lateral hypothalamic stimulation may act as an energizing, drive-arousing, operation to produce both avoidance and approach learning in cats.

Hemodynamic effects of electrical stimulation of forebrain angiotensin and osmosensitive sites

1978 ◽  
Vol 235 (4) ◽  
pp. H445-H451 ◽  
Keyword(s):  
Blood Flow ◽  
Electrical Stimulation ◽  
Arterial Pressure ◽  
Median Eminence ◽  
Regional Blood Flow ◽  
Renal Hypertension ◽  
Brain Structures ◽  
Ventromedial Hypothalamus ◽  
Pressure Changes ◽  
Stimulation Of

Previous studies from this laboratory have indicated an important role for angiotensin-sensitive anteroventral third ventricular (AV3V) brain structures in normal regulation of arterial pressure and development of renal hypertension. The present experiments examined the effects of electrical stimulation of these periventricular areas on arterial pressure and regional blood flow in the anesthetized rat. Electrodes were placed in the AV3V region 3–10 days prior to acute studies. Blood flow was measured in extracorporeal blood flow circuits. Electrical stimulation produced only small changes in arterial pressure. Despite the small pressure changes, stimulation caused marked frequency-dependent alterations in regional blood flow. Renal and splanchnic flows were reduced while hindlimb flow was increased. Resistance changes were abolished by surgical denervation or ganglionic blockade but were unaffected by adrenalectomy. Hemodynamic responses to AV3V stimulation were abolished by a lesion in the area of the median eminence. It may be concluded that AV3V stimulation, through activation of pathways descending through the ventromedial hypothalamus-median eminence region, produces profound regional blood flow shifts without greatly altering arterial pressure.

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