Activity of LH receptor, LH-stimulated cyclic AMP and testosterone production in the Leydig cell of heat-acclimatized rats

1984 ◽  
Vol 102 (2) ◽  
pp. 167-173 ◽  
Author(s):  
E. Bedrak ◽  
Z. Chap
Keyword(s):  
Relative Humidity ◽  
Cyclic Amp ◽  
Leydig Cell ◽  
Male Rats ◽  
Heat Acclimatization ◽  
Lh Receptor ◽  
Hot Environment ◽  
C 30 ◽  
Lower Capacity ◽  
Trophic Hormone

ABSTRACT Key reactions associated with the capacity of the isolated Leydig cell to synthesize testosterone were studied in male rats acclimatized to a hot environment (33–35 °C, 25–40% relative humidity) and controls (20–22 °C, 30–50% relative humidity). The results demonstrate that acclimatization to heat coincides with: (1) a lower number of human chorionic gonadotrophin (hCG) receptors (P<0·01) in the Leydig cell, (2) higher affinity of the Leydig cell for hCG (P < 0·05), (3) lower hCG-stimulated cyclic AMP production (P<0·05) by the Leydig cell and (4) lower capacity of the Leydig cell to synthesize testosterone (P<0·01) after hCG challenge. It is suggested that the major cellular alteration responsible for the decreased testosterone secretion by the Leydig cell lies distal to the step involving the binding of the trophic hormone to its receptor and that heat-acclimatization induces changes in the integrity of the various cellular membranes leading to the impeded function of adenylate cyclase and 17β-hydroxysteroid oxidoreductase. J. Endocr. (1984) 102, 167–173

SYNTHESIS OF ANDROGENS IN VITRO BY TESTES OF RATS ACCLIMATIZED TO A HOT ENVIRONMENT

1971 ◽  
Vol 51 (3) ◽  
pp. 489-498 ◽  
Author(s):  
E. BEDRAK ◽  
V. SAMOILOFF ◽  
U. A. SOD-MORIAH ◽  
S. GOLDBERG
Keyword(s):  
Growth Rate ◽  
Relative Humidity ◽  
Oxygen Uptake ◽  
Leydig Cells ◽  
Environmental Temperature ◽  
High Ambient Temperature ◽  
Male Rats ◽  
Similar Degree ◽  
Hot Environment

SUMMARY The relative activities of enzymes participating in the biosynthesis of testosterone via the 4-ene pathway were determined in testicular homogenates of rats acclimatized to a hot environment (33–35 °C, 25–40% relative humidity). Acclimatized animals showed an increase in activity of 17α-hydroxylase, 17,20-lyase and 20α-hydroxysteroid oxidoreductase, whereas the activity of 17β-hydroxysteroid oxidoreductase was markedly decreased. Histological examination of the testes disclosed that neither the germinal epithelium nor the Leydig cells were adversely affected by the increased environmental temperature. The results are discussed in relation to the synthesis and release of the gonadotrophins. A similar degree of acclimatization, as determined by the comparable decrease in oxygen uptake, was achieved by either of two methods: daily 4 h exposure to a high ambient temperature for 4 weeks or continuous maintenance at 35 °C. The former procedure, however, appeared to be the preferred method for acclimatization of male rats since it did not inhibit growth rate and was free of mortality.

Perfluoroundecanoic acid inhibits Leydig cell development in pubertal male rats via inducing oxidative stress and autophagy

2021 ◽  
Vol 415 ◽  
pp. 115440
Author(s):  
Haoni Yan ◽  
Changchang Li ◽  
Cheng Zou ◽  
Xiu Xin ◽  
Xiaoheng Li ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Leydig Cell ◽  
Cell Development ◽  
Male Rats

scholarly journals Immunohistochemical Review of Leydig Cell Lesions in Ochratoxin A-Treated Fischer Rats and Controls

Toxins ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 480 ◽  
Author(s):  
Diana Herman ◽  
Peter Mantle
Keyword(s):  
Testicular Cancer ◽  
Ochratoxin A ◽  
Leydig Cell ◽  
Dietary Exposure ◽  
Male Rats ◽  
Testicular Hypertrophy ◽  
Cellular Pathology ◽  
Rats And Mice ◽  
First Time

Ochratoxin A is best known as a potent renal carcinogen in male rats and mice after necessarily protracted ingestion, although valid extrapolation to any human disease has not been verified. The hypothesis that the toxin is a cause of human testicular cancer was proposed a decade ago and has proliferated since, partly through incomplete study of the scientific literature. Archived tumorous rat testes were available from Fischer F344 rats exposed to continuous dietary exposure for half of or the whole life in London in the 2000s. Renal cancer occurred in some of these cases and testicular tumours were observed frequently, as expected, in both treated and untreated animals. Application of clinical immunohistochemistry has for the first time consistently diagnosed the testicular hypertrophy in toxin-treated rats as Leydig cell tumours. Comparison is made with similar analysis of tumorous testes from control (untreated) rats from U.S. National Toxicology Program studies, both of ochratoxin A (1989) and the more recent one on Ginkgo biloba. All have been found to have identical pathology as being of sex cord-stromal origin. Such are rare in humans, most being of germinal cell origin. The absence of experimental evidence of any specific rat testicular cellular pathology attributable to long-term dietary ochratoxin A exposure discredits any experimental animal evidence of testicular tumorigenicity. Thus, no epidemiological connection between ochratoxin A and the incidence of human testicular cancer can be justified scientifically.

scholarly journals Pacing Adjustments Associated With Familiarization: Heat Versus Temperate Environments

2016 ◽  
Vol 11 (7) ◽  
pp. 855-860 ◽  
Author(s):  
Cyril Schmit ◽  
Rob Duffield ◽  
Christophe Hausswirth ◽  
Aaron J. Coutts ◽  
Yann Le Meur
Keyword(s):  
Relative Humidity ◽  
Performance Improvement ◽  
Perceptual Experience ◽  
Time Trial ◽  
Heat Acclimatization ◽  
Endurance Time ◽  
Pacing Strategy ◽  
Per Se ◽  
Specific Alteration ◽  
Physiological Acclimation

Purpose:To describe the effect of the initial perceptual experience from heat familiarization on the pacing profile during a freepaced endurance time trial (TT) compared with temperate conditions.Methods:Two groups of well-trained triathletes performed two 20-km TTs in either hot (35°C and 50% relative humidity [RH], n = 12) or temperate (21°C and 50% RH, n = 22) conditions, after standardization of training for each group before both trials. To ensure no physiological acclimation differences between conditions, the TTs for both groups were separated by 11 ± 4 d.Results:Performance improvement in the heat (11 ± 24 W) from the 1st to 2nd trial appeared comparable to that in temperate conditions (8 ± 14 W, P = .67). However, the specific alteration in pacing profile in the heat was markedly different than temperate conditions, with a change from “positive” to an “even” pacing strategy.Conclusions:Altered perceptions of heat during heat familiarization, rather than physiological acclimatization per se, may mediate initial changes in pacing and TT performance in the heat. These results highlight the need for athletes without time for sufficient heat acclimatization to familiarize themselves with hot conditions to reduce the uncertainty from behavior-based outcomes that may impede performance.

CANADIAN WILTSHIRE BACON: XXVII. EFFECT OF METHOD OF THAWING FROZEN PORK ON BACON QUALITY

1945 ◽  
Vol 23f (6) ◽  
pp. 363-372 ◽  
Author(s):  
W. Harold White ◽  
G. A. Grant ◽  
N. E. Gibbons
Keyword(s):  
Relative Humidity ◽  
Bacterial Growth ◽  
Prolonged Exposure ◽  
Lean Meat ◽  
Oxygen Formation ◽  
Weight Content ◽  
Keeping Quality ◽  
Water Curing ◽  
C 30

Frozen Wiltshire sides were defrosted at temperatures of 4.4°, 12.6°, and 21.0 °C. (40°, 55°, and 70° F.) in water; curing pickle; 5, 15, and 30% brines; and in air at high and low relative humidity. Differences due to defrosting procedure were determined by measurement of the thawing period, changes in weight, content of moisture and curing salts, surface bacterial growth, peroxide oxygen formation in the fat, and colour quality and brightness of the lean meat. The effect of method of thawing on keeping quality during storage at − 1.1 °C. (30° F.) was also studied.While significant differences were observed between individual thawing treatments in the various criteria employed, few consistent trends could be distinguished between the three temperatures and the four types of media. However, in general it appeared that the more suitable procedures were those that effected thawing within a reasonable period of time. Unduly prolonged exposure to any of the conditions was usually undesirable.

Age-Related Impairments of Testosterone and Luteinizing Hormone Secretions in Male Rats Involving Decreases of Cyclic AMP Production.

2012 ◽  
Vol 87 (Suppl_1) ◽  
pp. 532-532
Author(s):  
Cai-Yun Jian ◽  
Yi-An Chen ◽  
Chia-Hsin Chang ◽  
Sang-Jou Lin ◽  
Yung-Hsing Yeh ◽  
...  
Keyword(s):  
Luteinizing Hormone ◽  
Cyclic Amp ◽  
Male Rats ◽  
Age Related ◽  
Hormone Secretions

Diffusion of water vapor through human skin in hot environment and with application of atropine

1959 ◽  
Vol 14 (2) ◽  
pp. 276-278 ◽  
Author(s):  
Konrad J. K. Buettner ◽  
Frederick F. Holmes
Keyword(s):  
Water Vapor ◽  
Relative Humidity ◽  
Human Skin ◽  
Liquid Water ◽  
Water Loss ◽  
Diffusion Resistance ◽  
Vapor Transfer ◽  
Hot Environment ◽  
Human Forearm ◽  
Very High

At room temperatures between 20° and 40°C, vapor transfer through skin of human forearm was tested with four small heated bottles containing air of humidities ranging from 2 to 100% relative humidity. Exposure times ranging from 30 to 120 minutes had no influence on results. Water loss or gain of skin were observed for the different bottles. At very high humidities, liquid water deposit on the skin was measured by weighing a blotter. Skin vapor loss decreases systematically when bottle moisture increases. This increase is enhanced at room temperatures above 24℃, where total loss into a dry bottle increases more than fivefold. This increase seems only partially caused by sweat and partially by a decrease of the skin diffusion resistance. Tourniquet and locally applied atropine did not affect vapor transfer in a cool room. In a hot room, the tourniquet lowered the vapor loss by only 20%, whereas atropine drastically curtailed vapor loss. Submitted on August 25, 1958

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