THE EFFECT OF HYPOTHALAMIC LESIONS ON REPRODUCTIVE ACTIVITY IN SHEEP

1967 ◽  
Vol 39 (3) ◽  
pp. 415-NP ◽  
Author(s):  
H. M. RADFORD
Keyword(s):  
Median Eminence ◽  
Reproductive Activity ◽  
Mammillary Body ◽  
Optic Chiasma ◽  
Hypothalamic Lesions ◽  
Apparent Change ◽  
Electrolytic Lesions ◽  
Releasing Factors ◽  
Bilateral Lesions ◽  
Made In

SUMMARY Electrolytic lesions were made in the hypothalamus of 41 Merino ewes which were subsequently observed for 2–16 months. Ovarian inactivity resulted from bilateral medial and ventral lesions placed immediately posterior to the optic chiasma (four ewes) or immediately anterior to the mammillary body (five ewes). Failure to show oestrus while apparently still ovulating regularly was a feature in another four ewes in which bilateral medial and ventral lesions were placed between the sites already described. Small bilateral lesions in these ventral regions led initially to ovarian inactivity, but final re-establishment of apparently normal reproductive activity in three ewes. Bilateral lesions in regions other than those described above resulted in no apparent change in reproductive activity (eight ewes). Similarly, unilateral or asymmetrical lesions in the remaining 17 ewes failed to affect their reproductive activity. The results are consistent with the hypothesis that in sheep a region of the median eminence responsible for the production of gonadotrophin-releasing factors requires neural inputs traversing both anterior and posterior hypothalamic areas.

A QUANTITATIVE STUDY OF SPERMATOGENESIS IN RATS BEARING HYPOTHALAMIC LESIONS OF MAMMILLARY AND SUPRA-CHIASMATIC NUCLEI

1969 ◽  
Vol 60 (2) ◽  
pp. 276-280
Author(s):  
Bernard A. Rüedi
Keyword(s):  
Quantitative Analysis ◽  
Quantitative Study ◽  
Germinal Cell ◽  
Suprachiasmatic Nuclei ◽  
Hypothalamic Lesions ◽  
Cell Counts ◽  
Significant Change ◽  
Bilateral Lesions ◽  
Made In

ABSTRACT A quantitative analysis of spermatogenesis has been made in rats bearing bilateral lesions of the lateral mammillary nuclei or of the suprachiasmatic nuclei of the hypothalamus. There was no significant change in the germinal cell counts in lesioned rats as compared either with normal or with sham operated rats.

Production of diabetes insipidus in hypophysectomized rats by hypothalamic lesions

1961 ◽  
Vol 201 (5) ◽  
pp. 811-814 ◽  
Author(s):  
C. C. Gale ◽  
S. Taleisnik ◽  
S. M. McCann
Keyword(s):  
Diabetes Insipidus ◽  
Water Intake ◽  
Median Eminence ◽  
Urine Volume ◽  
Water Turnover ◽  
Hypothalamic Lesions ◽  
Significant Augmentation ◽  
Hypophysectomized Rats ◽  
Somatotrophic Hormone ◽  
Made In

Lesions in the median eminence produced permanent diabetes insipidus (DI) in chronically hypophysectomized rats. Water turnover in these animals, however, was only about half of that observed when lesions were made in rats with intact pituitaries and was further characterized by absence of the normal interphase. Conversely, when hypophysectomy was performed in rats with DI, an immediate and sustained 50% reduction in water intake occurred. Administration of adrenocorticotropin to hypophysectomized rats with lesions caused significant augmentation of DI, but not to levels found in rats with DI and intact pituitaries. Neither somatotrophic hormone (STH) nor triiodothyronine increased water turnover when given to hypophysectomized animals with DI. Lesions in the median eminence of hypophysectomized rats induced an immediate increase in urine volume in the absence of water intake, which indicates that primary polyuria was responsible at least in part for the development of DI in hypophysectomized rats with lesions.

LOCALIZATION OF HYPOTHALAMIC LESIONS INHIBITING ADRENAL WEIGHT MAINTENANCE IN THE RAT

1960 ◽  
Vol XXXIV (I) ◽  
pp. 19-26 ◽  
Author(s):  
Johannes Moll
Keyword(s):  
Median Eminence ◽  
Weight Maintenance ◽  
Brain Lesions ◽  
Pituitary Stalk ◽  
Adrenal Weight ◽  
Hypothalamic Lesions ◽  
Electrolytic Lesions ◽  
The Right

ABSTRACT Electrolytic lesions, approximately 1 mm in diameter, were placed at 20 regularly distributed points in the midline of the hypothalamus of rats. Eighteen days later the left adrenals were removed and weighed. Six days after this operation the animals were sacrificed and the right adrenals weighed. Animals without brain lesions but otherwise similarly treated, served as controls. The brains of all lesioned animals were studied histologically. Following lesions in the antero-basal and mid-basal hypothalamus the weights of both adrenals were subnormal. Compensatory adrenal hypertrophy was only slightly inhibited by the lesions. Lesions destroying the pituitary stalk and lesions in the median eminence, had no effect on adrenal weight.

PRECOCIOUS PUBERTY IN RATS WITH HYPOTHALAMIC LESIONS

1960 ◽  
Vol XXXIII (IV) ◽  
pp. 569-576 ◽  
Author(s):  
Ronald J. Gellert ◽  
William F. Ganong
Keyword(s):  
Precocious Puberty ◽  
Arcuate Nucleus ◽  
Anterior Hypothalamus ◽  
Female Rats ◽  
Vaginal Opening ◽  
Mammillary Body ◽  
Immature Female ◽  
Hypothalamic Lesions ◽  
Electrolytic Lesions

ABSTRACT Eight female rats with electrolytic lesions involving the arcuate nucleus in the posterior tuberal region of the hypothalamus matured significantly earlier than unoperated controls. Lesions placed in the anterior hypothalamus, mammillary body, hippocampus, cortex and thalamus of immature female rats had no effect on the age at which vaginal opening and first oestrus occurred.

EFFECT OF HYPOTHALAMIC LESIONS ON PITUITARY MELANOCYTE-STIMULATING HORMONE

1967 ◽  
Vol 39 (4) ◽  
pp. 485-NP ◽  
Author(s):  
S. TALEISNIK ◽  
J. DE OLMOS ◽  
R. ORÍAS ◽  
MARÍA E. TOMATIS
Keyword(s):  
Median Eminence ◽  
Male Rats ◽  
Posterior Lobe ◽  
Melanocyte Stimulating Hormone ◽  
Mammillary Bodies ◽  
Hypothalamic Lesions ◽  
Paraventricular Nuclei ◽  
Inhibiting Factor ◽  
Electrolytic Lesions ◽  
Stimulating Hormone

SUMMARY The effect on the content of melanocyte-stimulating hormone (MSH) activity in the pituitary of electrolytic lesions placed in different regions of the hypothalamus was studied in male rats. Lesions in the paraventricular nuclei resulted, after 15 days, in a decrease of pituitary MSH activity to 20·4 ± 4·5%/mg. gland as compared with the controls, without changes in the weight of the hypophyses. In a group of animals in which the lesions failed to destroy the paraventricular nuclei completely the MSH activity in the pituitary was 66·4 ± 7·5% of that of controls and the weight of the gland was significantly higher. Hypothalamic lesions in the median eminence of the tuber cinereum produced 24 hr. later a decrease of pituitary MSH activity to 6·6 ± 0·8%, but 15 days later the values/mg. gland were almost normal. Lesions placed in the mammillary bodies or in the nucleus caudatus did not affect pituitary MSH content. Extracts of stalk-median eminence or posterior lobe from animals with lesions in the paraventricular nuclei, failed to show MSH-releasing factor as it is found in intact animals, nor did they contain MSH-release-inhibiting factor. The results support the concept that the paraventricular nuclei are involved in the control of pituitary MSH secretion and suggest that the MSH content of the disconnected hypophysis is to some degree regulated autonomously.

HYPOTHALAMIC LESIONS AND ADRENAL FUNCTION IN THE CAT

1961 ◽  
Vol 38 (1) ◽  
pp. 88-98 ◽  
Author(s):  
Dorothy T. Krieger ◽  
Irving H. Wagman
Keyword(s):  
Median Eminence ◽  
Adrenal Function ◽  
Cortical Function ◽  
Hypothalamic Lesions ◽  
Electrolytic Lesions ◽  
Response To Stress ◽  
Adrenal Response ◽  
Adrenal Cortical Function

ABSTRACT Bilateral electrolytic lesions limited to the median eminence were produced stereotaxically in four cats which had previously shown positive responses (as measured by blood corticoid elevations) to exogenous corticotrophin (ACTH) and insulin hypoglycaemia. Following operation these animals exhibited low basal corticoid levels and an inability to respond to ACTH and an impaired response to stress. At autopsy they showed an increase in adrenal size and stainable cortical lipid. Operated controls had normal responses to both exogenous ACTH and insulin hypoglycaemia and had normal adrenal histology. Thus a lesion of the median eminence depresses adrenal cortical function by interference with release of steroid from the adrenal and not by inducing adrenal atrophy. This may be explained in part by the observation that median eminence lesions interfere with the adrenal response to exogenous ACTH.

HORMONAL BASIS FOR IMPAIRMENTS IN MILK SYNTHESIS AND MILK EJECTION FOLLOWING HYPOTHALAMIC LESIONS

1961 ◽  
Vol 23 (3) ◽  
pp. 303-316 ◽  
Author(s):  
C. C. GALE ◽  
S. TALEISNIK ◽  
H. M. FRIEDMAN ◽  
S. M. McCANN
Keyword(s):  
Median Eminence ◽  
Adrenal Glands ◽  
Regulatory Mechanisms ◽  
Adrenocorticotrophic Hormone ◽  
Milk Ejection ◽  
Hypothalamic Lesions ◽  
Severe Impairment ◽  
Electrolytic Lesions ◽  
Hypophysectomized Rats ◽  
Pituitary Secretion

SUMMARY The placing of electrolytic lesions in the median eminence of the hypothalamic tuber cinereum induces severe impairment of lactation in rats by causing deficiencies in pituitary secretion of adrenocorticotrophic hormone (ACTH; essential for milk synthesis) and of oxytocin (necessary for milk ejection). Thus, in rats with lesions given oxytocin × 2/day to permit milk ejection, it was observed that: (1) the severity of impairment in lactation correlated significantly with the degree of atrophy of the dams' adrenal glands; (2) administration of luteotrophin (LTH) failed to repair this defect in lactation; (3) when cortisol was administered milk production was markedly improved—to about 70–80% of normal for days 5–10—(a further slight increase in milk yield resulted when oxytocin injections were given every 4 hr. 'around the clock' to rats receiving cortisol therapy); and (4) administration of regimens consisting of either LTH and cortisol, or LTH, growth hormone (GH), and cortisol failed to improve lactation beyond levels attained with cortisol therapy alone. In hypophysectomized rats replacement with cortisol and LTH, plus oxytocin × 2/day, permitted substantial synthesis which was not significantly improved further when GH was added to the regimen, and which promptly declined when LTH therapy was withdrawn. Since no deficiency in secretion of LTH could be demonstrated in lactating rats with lesions given hormonal replacement, these data provide evidence that elimination of hypothalamic regulatory mechanisms by hypothalamic lesions is compatible with secretion of large amounts of LTH. This demonstration that lesions in the median eminence block release of ACTH while permitting continued secretion of LTH indicates that the hypothalamic mechanisms regulating their release are not identical.

Specific alterations in sodium chloride intake after hypothalamic lesions in the rat

1963 ◽  
Vol 205 (5) ◽  
pp. 922-926 ◽  
Author(s):  
Miguel R. Covian ◽  
José Antunes-Rodrigues
Keyword(s):  
Sodium Chloride ◽  
Urinary Excretion ◽  
The Other ◽  
Urinary Output ◽  
Water Ingestion ◽  
Hypothalamic Lesions ◽  
Paraventricular Nuclei ◽  
Electrolytic Lesions ◽  
Specific Increase ◽  
Sodium Chloride Intake

Bilateral electrolytic lesions in the hypothalamus of the rat elicited either a decrease or increase in 2% NaCl intake, without a significant change in water ingestion. Lesions placed in the anterior hypothalamus involving supraoptic or paraventricular nuclei, or both, resulted in a conspicuous fall (as much as 93%) of NaCl intake. The decreased consumption remained to the end of the experiments which in some rats lasted 105 days and was accompanied by a decrease in NaCl urinary output. On the contrary, lesions placed in the central hypothalamus determined a specific increase of NaCl intake together with an augmented urinary excretion. The increased ingestion was permanent and lasted to the end of the experiment, attaining in one rat the value of 290%. To account for these results two provisional explanations are advanced, one of them considering the possibility of the existence of two areas of opposite effects regarding NaCl ingestion and the other claiming a neurohumoral mechanism in which oxytocin and aldosterone could be the two responsible hormones.

Effects of Median Cortex Lesions on the Maternal Behavior of the Rat

1963 ◽  
Vol 13 (3) ◽  
pp. 835-838 ◽  
Author(s):  
William E. Wilsoncroft
Keyword(s):  
Maternal Behavior ◽  
Quantitative Measure ◽  
The Other ◽  
Anterior Cingulate ◽  
Continuous Recording ◽  
Cortical Lesions ◽  
Air Blast ◽  
Posterior Cingulate ◽  
Electrolytic Lesions ◽  
Made In

This study explores the relation of cortical lesions to the rat's maternal behavior. Rather precise electrolytic lesions were made in the anterior and posterior cingulate areas of the median cortex. A quantitative measure of maternal behavior was obtained by a continuous recording of the rat's movements about the observation box and her picking up and depositing of pups in response to scattering the litter and directing air and heat blasts onto the litter. Data indicate (1) the lesions were differential in their effect. Only the anterior cingulate lesions produced significant disruptions in the maternal behaviors. (2) The lesions disrupted only certain sequential aspects of the maternal activities. The groups did not differ in their over-all retrieving behavior or in the number of pups they removed from the air blast. However, the anterior cingulate lesioned animals were observed to carry their pups several times around the observation box before depositing them; thus they carried their pups over significantly more floor areas than did the other groups. Further, these animals exhibited other unique behaviors such as repeatedly picking up and dropping the same pup or retrieving their own tails time after time.

URINARY 17-HYDROXYCORTICOSTEROID EXCRETION IN GUINEA-PIGS WITH HYPOTHALAMIC LESIONS

1966 ◽  
Vol 53 (3) ◽  
pp. 369-381 ◽  
Author(s):  
Bryant Benson
Keyword(s):  
Guinea Pig ◽  
Cold Exposure ◽  
Guinea Pigs ◽  
Insulin Injection ◽  
Self Control ◽  
Base Line ◽  
Acth Secretion ◽  
Anatomic Site ◽  
Hypothalamic Lesions ◽  
Bilateral Lesions

ABSTRACT An attempt was made to localize an anatomic site in the hypothalamus where mechanisms are to be found for the control of pituitary adrenocorticotrophin (ACTH) secretion in the adult male guinea-pig. Daily urinary 17-hydroxycorticosteroid (17-OHCS) excretion and the effects of cold exposure and insulin on base-line 17-OHCS excretion levels were determined preoperatively. Each animal acted as a self control. Bilateral electrolytic coagulation lesions were placed in a variety of hypothalamic sites in sixty-eight animals, and base-line 17-OHCS excretion levels and the 17-OHCS response to cold exposure and insulin injection were again determined. Preoperative and postoperative values were compared and the ablated anatomic sites noted. Animals with bilateral lesions in the ventromedian and dorsomedian nuclei displayed a significant reduction in daily 17-OHCS excretion, and 17-OHCS responses to cold exposure and insulin injection. Animals with posterior hypothalamic lesions and sham operated animals had postoperative daily 17-OHCS values and 17-OHCS responses to cold and to insulin that were above or equal to the preoperative values. It was postulated that in the guinea-pig the hypothalamic mechanisms in control of ACTH are to be found in the middle and anterior hypothalamus, in the neuropil associated with the ventromedian and dorsomedian nuclei.

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