Increase in sensitivity of the baroreceptor reflex following microinjection of carbachol into the posterior hypothalamic nucleus of awake rats

2016 ◽  
Vol 36 (1-2) ◽  
pp. 3-13 ◽  
Author(s):  
C. R. Newey ◽  
J. R. Martin
Keyword(s):  
Baroreceptor Reflex ◽  
Hypothalamic Nucleus ◽  
Posterior Hypothalamic Nucleus ◽  
Awake Rats

Injection of muscimol into posterior hypothalamus blocks stress-induced tachycardia

1989 ◽  
Vol 257 (1) ◽  
pp. R246-R251 ◽  
Author(s):  
M. Lisa ◽  
E. Marmo ◽  
J. H. Wible ◽  
J. A. DiMicco
Keyword(s):  
Gaba Receptors ◽  
Potential Role ◽  
Hypothalamic Nucleus ◽  
Gamma Aminobutyric Acid ◽  
Similar Treatment ◽  
Cardiovascular Changes ◽  
Vehicle Treatment ◽  
Response To Stress ◽  
Posterior Hypothalamic Nucleus

We have previously shown that the physiological and behavioral manifestations of emotional stress are produced when drugs impairing gamma-aminobutyric acid (GABA)-mediated synaptic inhibition are injected into the posterior hypothalamic nucleus in rats [Wible, J.H., Jr., F.C. Luft, and J.A. DiMicco. Am. J. Physiol. 254 (Regulatory Integrative Comp. Physiol. 23): R680-R687, 1988]. The purpose of this study was to assess further the potential role of GABA receptors in this region in the response to stress using muscimol, a GABAA receptor agonist. In six chronically instrumented conscious rats, air stress after vehicle treatment evoked marked and sustained tachycardia (+130 +/- 14 beats/min at +10 min) accompanied by a less dramatic increase in arterial pressure (+14 +/- 3 mmHg). Microinjection of muscimol (10 ng; 88 pmol) at the same posterior hypothalamic site in which GABA blockade causes cardiovascular changes similar to those seen in stress produced a modest depression of cardiovascular function in unstressed animals (-28 +/- 5 beats/min and -6 +/- 3 mmHg). However, similar treatment with muscimol virtually abolished the stress-induced tachycardia in the same rats (+9 +/- 8 beats/min), while having no significant effect on baroreflex-evoked increases in heart rate caused by intravenous infusion of sodium nitroprusside (4 micrograms). These findings support a role for activation of neurons in the posterior nucleus of the hypothalamus in the generation of stress-induced cardiovascular changes and for control of this mechanism by local GABA receptors.

Hemodynamic effects of posterior hypothalamic injection of neuropeptide Y in awake rats

1991 ◽  
Vol 261 (3) ◽  
pp. H814-H824 ◽  
Author(s):  
J. R. Martin ◽  
M. M. Knuepfer ◽  
T. C. Westfall
Keyword(s):  
Heart Rate ◽  
Cardiac Output ◽  
Neuropeptide Y ◽  
Cardiovascular System ◽  
Peripheral Resistance ◽  
Hypothalamic Nucleus ◽  
Initial Increase ◽  
System Control ◽  
Posterior Hypothalamic Nucleus ◽  
Freely Moving

Unilateral microinjection of neuropeptide Y (NPY) into the posterior hypothalamic nucleus was previously found to evoke a sympathoexcitatory-mediated increase in mean arterial pressure (MAP) in urethan-anesthetized rats. In this study, the effect of unilateral injection of NPY into the posterior hypothalamic nucleus on the cardiovascular system of conscious, freely moving rats was determined. Microinjection of NPY (0.2-2.4 nmol) or the cholinergic agonist carbachol (0.5-5.5 nmol) resulted in concentration-dependent increases in MAP. Pretreatment of animals with 7.5 mg/kg iv of the ganglionic blocker pentolinium resulted in a blockade of the increase in MAP evoked by microinjection of NPY (2.4 nmol) or carbachol (3.3 nmol). Despite their similarity of effects on MAP, NPY and carbachol evoked different changes in heart rate. NPY increased heart rate, whereas carbachol evoked a biphasic change in heart rate that consisted of an initial increase followed by a decrease. In addition, carbachol caused increases in both hindquarter and mesenteric vascular resistances, whereas NPY caused a short-lasting increase in mesenteric resistance and a tendency toward an increase in hindquarter resistance. Both NPY and carbachol increased total peripheral resistance while NPY decreased stroke volume. Cardiac output was not significantly affected by either NPY or carbachol, although NPY had a tendency to decrease cardiac output. These results suggest that microinjection of NPY or carbachol into the posterior hypothalamic nucleus of conscious rats evokes an increase in MAP primarily as a result of sympathoexcitation and that NPY and carbachol selectively affect autonomic nervous system control of the cardiovascular system.

Functional MRI response and correlated electrophysiological changes during posterior hypothalamic nucleus deep brain stimulation

NeuroImage ◽  
2011 ◽  
Vol 56 (1) ◽  
pp. 35-44 ◽  
Author(s):  
Calvin K. Young ◽  
Andrew R. Brown ◽  
Jordan H.B. Robinson ◽  
Ursula I. Tuor ◽  
Jeff F. Dunn ◽  
...  
Keyword(s):  
Deep Brain Stimulation ◽  
Functional Mri ◽  
Brain Stimulation ◽  
Hypothalamic Nucleus ◽  
Posterior Hypothalamic Nucleus ◽  
Deep Brain

Histomorphological Studies on the Different Nuclei of Hypothalamus of Indian Buffalo

2020 ◽  
Author(s):  
Devendra Pathak ◽  
Neelam Bansal
Keyword(s):  
Supraoptic Nucleus ◽  
Arcuate Nucleus ◽  
Hypothalamic Nucleus ◽  
Endocrine Gland ◽  
Tissue Samples ◽  
Optic Chiasma ◽  
Cell Groups ◽  
Posterior Hypothalamic Nucleus ◽  
Neurosecretory Substance ◽  
Reproductive Phases

Background: Hypothalamus is an integral part of the hypothalamo-hypophyseal ovarian axis. It contains several small nuclei that have been implicated in several specialized functions. It is the master endocrine gland because it regulates the activity of the pituitary. The present investigation was planned to elucidate the histomorphological details of different nuclei in the hypothalamus of Indian buffaloes. Methods: The hypothalami of buffaloes (n =52) were collected from local abattoirs and Teaching Veterinary Clinical Complex, GADVASU, Ludhiana. The tissue samples were collected from three levels i.e. the supraoptic, tuberal and the mamillary region of the hypothalamus and processed for paraffin sectioning and the sections were stained with various stains for histomorphological studies. Result: The well-defined cell groups or nuclei were identified both in the coronal and sagittal sections of the hypothalamus in all the reproductive phases. Eight nuclei were distinctly recognized in buffalo hypothalamus at three levels in the coronal sections of the hypothalamus. At the level of optic chiasma, the nuclei were paraventricular nucleus (PVN), supraoptic nucleus (SON) and preopticnucleus (PON); at the tuberal region, there were arcuate nucleus (AN) and ventromedial nucleus (VMN) and at the mammillary region, the lateral mammillary nucleus (LMN), medial mammillary nucleus (MMN) and posterior hypothalamic nucleus (PHN) were identified. Most of the nuclei consisted of a loose or compact heterogeneous collection of neurons. The neurons of the different nuclei were of variable shape. The cytoplasm contained a varied amount of Nissl material. The neurosecretory substance was peripheral in position. Small to large-sized blood vessels were observed in between the neuronal substance. The size of the neurons varied during different stages of reproduction.

Inhibitory influence of the nuclei of the posterior hypothalamus on the pro-oestrous surge of LH

1984 ◽  
Vol 105 (4) ◽  
pp. 433-440 ◽  
Author(s):  
C. Beltramino ◽  
S. Taleisnik
Keyword(s):  
Posterior Hypothalamus ◽  
Female Rats ◽  
Hypothalamic Nucleus ◽  
Inhibitory Influence ◽  
Medial Basal Hypothalamus ◽  
Mammillary Bodies ◽  
Ventromedial Hypothalamic Nucleus ◽  
Hypothalamic Nuclei ◽  
Posterior Hypothalamic Nucleus ◽  
Lh Release

Abstract. The effect of transecting caudal afferents to the medial basal hypothalamus on the pro-oestrous surge of LH was studied in cyclic female rats. Rats with transverse cuts placed just in front of the mammillary bodies and caudal to the ventromedial hypothalamic nucleus showed an earlier time of onset of pro-oestrous surge of LH. Conversely, rats with transverse cuts placed 2 mm more caudally or with cuts along the lateral edges of the hypothalamus showed no altered release of LH. Advanced release of LH occurred also in rats in which the ventral premammillary nuclei or the posterior hypothalamic nuclei were bilaterally destroyed but not in those sham operated or with lesions in the dorsal premammillary nuclei. The number of ova ovulated was higher in rats bearing lesions of any of these nuclei but enhanced LH release was seen only in animals with lesions of the posterior hypothalamic nuclei. Electrochemical stimulation (anodic d.c., 100 μA, 15 s) applied at noon of pro-oestrus to the ventral premammillary nucleus, dorsal premammillary nucleus or posterior hypothalamic nucleus prevented ovulation and the preovulatory discharge of LH. It is concluded that inputs from nuclei of the posterior hypothalamus are inhibitory for LH release and could participate in determining the timing and magnitude of the pro-oestrous surge of the hormone.

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