The origin of the vasopressinergic and oxytocinergic fibres of the external region of the median eminence of the rat hypophysis

1977 ◽  
Vol 180 (4) ◽  
pp. 443-452 ◽  
Author(s):  
F. Vandesande ◽  
K. Dierickx ◽  
J. De Mey
Keyword(s):  
Median Eminence ◽  
External Region

Ultrastructural Localization of Acetylcholinesterase in the Arcuate Nucleus and Median Eminence of the Rat

1977 ◽  
Vol 35 ◽  
pp. 440-441
Author(s):  
K.A. Carson ◽  
C.B. Nemeroff ◽  
M.S. Rone ◽  
J.S. Kizer ◽  
J.S. Hanker
Keyword(s):  
Choline Acetyltransferase ◽  
Median Eminence ◽  
Arcuate Nucleus ◽  
Cholinergic Neurons ◽  
Ultrastructural Localization ◽  
Male Rats ◽  
Neonatal Rats ◽  
Good Marker ◽  
Chemical Studies ◽  
High Doses

Biochemical, physiological, pharmacological, and more recently enzyme histo- chemical data have indicated that cholinergic circuits exist in the hypothalamus. Ultrastructural correlates of these pathways such as acetylcholinesterase (AchE) positive neurons in the arcuate nucleus (ARC) and stained terminals in the median eminence (ME) have yet to be described. Initial studies in our laboratories utilizing chemical lesioning and microdissection techniques coupled with microchemical and light microscopic enzyme histo- chemical studies suggested the existence of cholinergic neurons in the ARC which project to the ME (1). Furthermore, in adult male rats with Halasz deafferentations (hypothalamic islands composed primarily of the isolated ARC and the ME) choline acetyltransferase (ChAc) activity, a good marker for cholinergic neurons, was not significantly reduced in the ME and was only somewhat reduced in the ARC (2). Treatment of neonatal rats with high doses of monosodium 1-glutamate (MSG) results in a lesion largely restricted to the neurons of the ARC.

HYPERTROPHIC ADRENALS AND THEIR RESPONSE TO STRESS AFTER LESIONS IN THE MEDIAN EMINENCE OF TOTALLY HYPOPHYSECTOMIZED PIGEONS

1961 ◽  
Vol 37 (4) ◽  
pp. 565-576 ◽  
Author(s):  
Richard A. Miller
Keyword(s):  
Dose Response ◽  
Median Eminence ◽  
Response Curve ◽  
Liver Parenchyma ◽  
Dose Response Curve ◽  
Pars Distalis ◽  
Adrenal Enlargement ◽  
Response To Stress ◽  
Lethal Doses ◽  
Chromaffin Tissue

ABSTRACT Four per cent formaldehyde, insulin, or epinephrine in oil was injected for 5 days into pigeons subjected to varying degrees of hypophysectomy alone or together with large lesions in the median eminence and hypothalamus. Adrenals atrophied after the removal of the pars distalis alone or together with the neurohypophysis in untreated pigeons but showed markedly hypertrophic interrenal tissue (cortex in mammals) after treatment with formaldehyde or insulin. The slope of the dose-response curve was similar in operated and unoperated pigeons. The accumulation of bile in the liver parenchyma, which may occur after removal of the pars distalis, is an endogenous stress which was associated regularly with adrenal hypertrophy. After very large lesions of the median eminence and ventral hypothalamus in addition to total hypophysectomy, adrenals hypertrophied rather than atrophied, and the response to formaldehyde paralleled that in intact and »hypohysectomized« pigeons. Interrenal tissue was stimulated regularly; chromaffin tissue was partially degranulated, sometimes showed hyperplasia with colchicine, but only occasionally appeared hypertrophied. Epinephrine in nearly lethal doses caused only minimal adrenal enlargement. After adrenal denervation followed by hypophysectomy, the adrenals were still stimulated by formaldehyde. It appears that the interrenal tissue of the pigeon responds to a humoral stimulus not of hypophyseal origin in the absence of the hypophyseal-hypothalamic system.

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.

THE RELATION BETWEEN THE HYPOTHALAMIC NEUROSECRETION AND THE CORTICOTROPHIN RELEASE IN EXPERIMENTAL CONDITIONS

1960 ◽  
Vol XXXIV (I) ◽  
pp. 8-18 ◽  
Author(s):  
E. Kivalo ◽  
U. K. Rinne
Keyword(s):  
Paraventricular Nucleus ◽  
Median Eminence ◽  
Supraoptic Nucleus ◽  
Acute Stress ◽  
Neurosecretory Material ◽  
Experimental Conditions ◽  
Hypothalamic Cells ◽  
The One ◽  
Hypophysial Portal ◽  
Acth Release

ABSTRACT Acute stress, chronic stress plus hydration, cortisone treatment, cortisone treatment plus dehydration were used as methods of investigation and the relation between the neurosecretory activity of the hypothalamic supraoptic nucleus and paraventricular nucleus and the neurosecretory material around the hypophysial portal vessels of the median eminence on the one hand and the corticotrophin release on the other hand, has been studied in the rat. Whereas stress stimulates both the activity of the above mentioned cells of the hypothalamus and the ACTH release, stress plus hydration causes a depression of these hypothalamic cells but nevertheless causes a marked ACTH release. Cortisone inhibits the activity of the cells in the supraoptic nucleus and the paraventricular nucleus as well as the ACTH release whereas cortisone plus dehydration causes stimulation but inhibits the ACTH release. In some stress and cortisone treatment groups the variations of the neurosecretory material around the hypophysial portal vessels and of the ACTH release were found to show a correlation. It is concluded that the activity of the cells of the supraoptic nucleus and the paraventricular nucleus and the ACTH release do not seem to have any definite connection, whereas some observations indicate that the neurosecretory material in the region of the median eminence around the hypophysial portal vessels may have some significance in ACTH release.

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