Gonadotropic activity of neonatal pituitary glands implanted in the rat brain

1962 ◽  
Vol 202 (3) ◽  
pp. 387-391 ◽  
Author(s):  
Karl M. Knigge
Keyword(s):  
Rat Brain ◽  
Preoptic Area ◽  
Male Rats ◽  
Adrenal Weight ◽  
Testis Weight ◽  
Pars Distalis ◽  
Neonatal Rats ◽  
Histological Sections ◽  
Pituitary Glands ◽  
Gonadotropic Activity

Pituitary glands of neonatal rats were implanted by stereotaxic methods in various hypothalamic areas of the brains of adult, hypophysectomized male rats. Of 58 implantations, 44 viable grafts composed of pars distalis, intermedia, and epithelioid-like nervosa were found 3 months later. In none of the graft-bearing animals was there any evidence of thyrotropic or corticotropic activity as judged by thyroid or adrenal weight, I131 uptake, or plasma free corticosteroids. In 18 graft-bearing animals, testicular weights ranged from 831 to 2,118 mg, compared to mean testis weight of 165 mg for hypophysectomized, nonimplanted animals. Histological sections of testes from these graft-bearing animals revealed active spermatogenesis. In each implanted animal with testicular maintenance, the pituitary graft was situated in the floor of the hypothalamus, encroaching upon or interrupting fibers of the supraopticohypophyseal tract. Adenohypophyseal cells which appeared to be nearest or more intimately related to these fibers were large (12–20µ), vacuolated, and contained abundant fuchsinophilic granules typical of castration cells. Other chromophil types were not present. In all nonfunctional grafts (situated in preoptic area, septum, anterior hypothalamus, and mammillary region) adenohypophyseal cells were uniformly small and chromophobic.

LUTEINIZING HORMONE RELEASING FACTOR IN ULTRAFILTRATES OF BLOOD COLLECTED FROM THE PITUITARY STALK OF OVARIECTOMIZED RATS AND RATS SUBJECTED TO ELECTRICAL STIMULATION OF THE PREOPTIC AREA

1972 ◽  
Vol 54 (2) ◽  
pp. 227-237 ◽  
Author(s):  
H. G. BURGER ◽  
G. FINK ◽  
V. W. K. LEE
Keyword(s):  
Electrical Stimulation ◽  
Luteinizing Hormone ◽  
Preoptic Area ◽  
Male Rats ◽  
Pituitary Stalk ◽  
Ovariectomized Rats ◽  
Serum Lh ◽  
Pituitary Glands ◽  
The Brain ◽  
Stimulation Of

SUMMARY The presence of luteinizing hormone releasing factor (LH-RF) activity was investigated in pituitary stalk and systemic blood collected from rats ovariectomized at least 3 weeks previously, and in stalk blood from male rats in which electrodes had been implanted in the medial preoptic area of the brain. Most of the assayable luteinizing hormone (LH) present in the blood samples was eliminated by acid-ethanol extraction followed by ultrafiltration. The ultrafiltrates were injected into ovariectomized rats treated with oestrogen and progesterone, and increments in the concentration of LH in the sera of these animals, estimated by radioimmunoassay, were taken as an indication that the filtrate was able to release LH from the anterior pituitary gland. The ultrafiltrates of both the stalk and systemic plasma from the ovariectomized rats exhibited LH-RF activity as did the ultrafiltrates of blood collected from the pituitary stalk of the male rats during electrical stimulation of the preoptic area; stalk blood collected from these animals before the current was applied appeared to be inactive. The LH-RF activity of the ultrafiltrates of systemic and pituitary stalk plasma taken from ovariectomized rats was similar, and, therefore, the possibility is raised that the response of the pituitary glands in ovariectomized rats treated with oestrogen and progesterone is of an all or none type. The presence of appreciable quantities of LH-RF in the systemic plasma of ovariectomized rats may explain the discrepancy between bioassay and immunoassay estimates of LH in the plasma of these animals. The rapid increase in the concentration of serum LH and in the LH-RF activity of pituitary stalk plasma which followed stimulation of the preoptic area suggests that this region of the brain may be important in the control of the secretion of LH in the male as well as in the female animal.

Fine Structural Changes in the Adenohypophyses of Rats Following Destruction of the Pituitary Stalk

1977 ◽  
Vol 35 ◽  
pp. 496-497
Author(s):  
K. Kovacs ◽  
E. Horvath ◽  
J. M. Bilbao ◽  
F. A. Laszlo ◽  
I. Domokos
Keyword(s):  
Structural Changes ◽  
Tissue Injury ◽  
Anterior Lobe ◽  
Uranyl Acetate ◽  
Male Rats ◽  
Pituitary Stalk ◽  
Sequence Of Events ◽  
Pituitary Glands ◽  
Electrolytic Lesions ◽  
Ultrathin Sections

Electrolytic lesions of the pituitary stalk in rats interrupt adenohypophysial blood flow and result in massive infarction of the anterior lobe. In order to obtain a deeper insight into the morphogenesis of tissue injury and to reveal the sequence of events, a fine structural investigation was undertaken on adenohypophyses of rats at various intervals following destruction of the pituitary stalk.The pituitary stalk was destroyed electrolytically, with a Horsley-Clarke apparatus on 27 male rats of the R-Amsterdam strain, weighing 180-200 g. Thirty minutes, 1,2,4,6 and 24 hours after surgery the animals were perfused with a glutaraldehyde-formalin solution. The skulls were then opened and the pituitary glands removed. The anterior lobes were fixed in glutaraldehyde-formalin solution, postfixed in osmium tetroxide and embedded in Durcupan. Ultrathin sections were stained with uranyl acetate and lead citrate and investigated with a Philips 300 electron microscope.

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.

REPRODUCTIVE TOXICITY OF CHLORPYRIFOS, CYPERMETHRIN AND THEIR INTERACTION IN MALE ALBINO RATS

2018 ◽  
pp. 69-86
Author(s):  
Asmaa ELnamaky ◽  
Amal Halawa ◽  
Mamdouh Abouelmaged
Keyword(s):  
Reproductive Toxicity ◽  
Prostatic Acid Phosphatase ◽  
Serum Levels ◽  
Reproductive Organs ◽  
Male Rats ◽  
Albino Rats ◽  
Glutathione S Transferase ◽  
Significant Drop ◽  
Sperm Abnormalities ◽  
Pituitary Glands

he present work was designed to investigate the reproductive toxicity induced by oral administration of chlorpyrifos (CPF), cypermethrin (CYP) and their combination in adult male albino rats. Forty mature male albino rats were separated into four groups (10 each), the first group was used as control, while second, third and fourth groups received orally 1/20 LD50 of CPF (10 mg/kg b.wt), 1/20 LD50 of CYP (17.22 mg/kg b.wt) and 1/40 LD50 of CPF plus 1/40 LD50 of CYP (5 mg/kg b.wt CPF plus 8.61 mg/kg b.wt CYP) respectively for 26 days. The results revealed that exposure to CPF and/or CYP induced a significant decrease in the reproductive organs weight. Moreover, a significant decrease in spermatic picture (sperm cell concentration and viability) was observed with high percent of sperm abnormalities. Serum levels of testosterone and pituitary gonadotropins (FSH and LH) have been declined significantly in all treated groups. Significant elevations were observed in malondialdehyde and nitric oxide concentrations, while antioxidant enzymes superoxide dismutase and glutathione-S-transferase activities were decreased significantly as a result of induced oxidative stress. A significant drop in prostatic acid phosphatase activity was observed. Additionally, the results showed some histopathological alterations in the reproductive organs as well as neurological lesions in brain and pituitary glands. In conclusion, CPF and CYP induce deleterious effects on reproductive efficiency of male rats which reflect more obvious impacts when both combined

Use of Both Fluoro-Jade B and Hematoxylin and Eosin to Detect Cell Death in the Juvenile Rat Brain Exposed to NMDA-Receptor Antagonists or GABA-Receptor Agonists in Safety Assessment

2021 ◽  
pp. 019262332110077
Author(s):  
Catherine A. Picut ◽  
Odete R. Mendes ◽  
David S. Weil ◽  
Sarah Davis ◽  
Cynthia Swanson
Keyword(s):  
Cell Death ◽  
Nmda Receptor ◽  
Rat Brain ◽  
Neuronal Cell Death ◽  
Neuronal Cell ◽  
Nmda Receptor Antagonists ◽  
Neonatal Rats ◽  
Receptor Antagonists ◽  
Fluoro Jade B ◽  
Hematoxylin And Eosin

Administration of pediatric anesthetics with N-methyl D-aspartate (NMDA)-receptor antagonist and/or γ-aminobutyric acid (GABA) agonist activities may result in neuronal degeneration and/or neuronal cell death in neonatal rats. Evaluating pediatric drug candidates for this potential neurotoxicity is often part of overall preclinical new drug development strategy. This specialized assessment may require dosing neonatal rats at postnatal day 7 at the peak of the brain growth spurt and evaluating brain tissue 24 to 48 hours following dosing. The need to identify methods to aid in the accurate and reproducible detection of lesions associated with this type of neurotoxic profile is paramount for meeting the changing needs of neuropathology assessment and addressing emerging challenges in the neuroscience field. We document the use of Fluoro-Jade B (FJB) staining, to be used in conjunction with standard hematoxylin and eosin staining, to detect acute neurodegeneration and neuronal cell death that can be caused by some NMDA-receptor antagonists and/or GABA agonists in the neonatal rat brain. The FJB staining is simple, specific, and sensitive and can be performed on brain specimens from the same cohort of animals utilized for standard neurotoxicity assessment, thus satisfying animal welfare recommendations with no effect on achievement of scientific and regulatory goals.

Effects of trenbolone acetate and testosterone on growth and on plasma concentrations of corticosterone and ACTH in rats

1990 ◽  
Vol 126 (3) ◽  
pp. 461-466 ◽  
Author(s):  
M. N. Sillence ◽  
R. G. Rodway
Keyword(s):  
Weight Gain ◽  
Growth Response ◽  
Plasma Concentrations ◽  
Female Rats ◽  
Male Rats ◽  
Adrenal Weight ◽  
Trenbolone Acetate ◽  
Male And Female Rats ◽  
Age Related ◽  
Old Rats

ABSTRACT The effects of trenbolone acetate (TBA) on growth and on plasma concentrations of corticosterone were examined in male and female rats. At 5 weeks of age, rats were injected with TBA (0·8 mg/kg) dissolved in peanut oil, or with oil alone, daily for 10 days. In female rats, TBA caused an increase in weight gain (20–38%), a reduction in adrenal weight (19%) and a reduction in plasma concentrations of corticosterone (55%). In contrast, TBA-treated male rats showed no significant increase in weight gain, no significant change in adrenal weight and no reduction in plasma concentrations of corticosterone. The mechanism by which adrenal activity was suppressed in TBA-treated female rats was examined and the response compared with that to testosterone. Female rats (8 weeks old) were injected daily either with oil vehicle, TBA (0·8 mg/kg) or testosterone propionate (0·8 mg/kg). Testosterone increased weight gain (24%), but the growth response to TBA treatment was significantly greater (97%). A reduction in plasma concentrations of corticosterone (45%) was again observed in response to TBA. However, testosterone increased plasma concentrations of corticosterone (52%) above those of control values. Neither androgen affected plasma concentrations of ACTH. Finally, the effects of TBA were examined in 6-week-old female rats, to characterize further the apparent age-related increase in responsiveness. The growth response of 6-week-old rats (60–74%) was intermediate between that seen in 5- and 8-week-old animals. It is concluded that part of the anabolic activity of TBA may be related to a reduction in circulating concentrations of corticosterone. The effect of TBA on corticosterone concentrations differs from that of the natural androgen, testosterone, and does not appear to be mediated by a reduction in plasma concentrations of ACTH. Journal of Endocrinology (1990) 126, 461–466

OVULATORY DISCHARGE OF GONADOTROPHINS INDUCED BY HYPOTHALAMIC STIMULATION IN CASTRATED MALE RATS BEARING A TRANSPLANTED OVARY

1966 ◽  
Vol 51 (2) ◽  
pp. 281-289 ◽  
Author(s):  
J. Moll ◽  
G. H. Zeilmaker
Keyword(s):  
Electrical Stimulation ◽  
Preoptic Area ◽  
Hypothalamic Stimulation ◽  
Male Rats ◽  
Corpora Lutea ◽  
Histological Changes ◽  
Experimental Animals ◽  
Cumulus Oophorus ◽  
Dc Current ◽  
Stimulation Of

ABSTRACT Castrated young adult inbred male rats bearing ovarian transplants were subjected to electrical stimulation of the hypothalamus. This was done in order to investigate whether discharge of ovulatory amounts of gonadotrophins could be induced in such male animals by this procedure. Bilateral stimulations with unipolar electrodes and a DC current of 1.5 mA applied during 10 seconds induced in the ovarian grafts histological changes indicating the discharge of ovulatory amounts of gonadotrophins. In animals killed one day after stimulation these changes consisted of displacement of the ova towards the centre of the follicles with loosening of the cumulus oophorus. In one animal the ova had left the follicles. In animals killed three days after stimulation numerous young corpora lutea could be observed. These results were obtained with electrode tips either close to the median eminence, or in the preoptic area. Shamstimulations were ineffective. Some of the experimental animals received progesterone pretreatment. This rendered the stimulations ineffective, if continued until the day preceding stimulation, but seemed without effect on the results of stimulation, if two or three days without progesterone preceded the stimulations.

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