EFFECTS OF AGE AND TESTICULAR FUNCTION ON THE PITUITARY–THYROID SYSTEM IN MALE RATS

1979 ◽  
Vol 82 (1) ◽  
pp. 53-59 ◽  
Author(s):  
H. J. CHEN ◽  
P. G. WALFISH
Keyword(s):  
Age Groups ◽  
Male Rats ◽  
Male Rat ◽  
Testicular Function ◽  
Thyrotrophin Releasing Hormone ◽  
Thyroid Gland Function ◽  
Young Rats ◽  
Specific Effects ◽  
Old Rats ◽  
Gland Function

SUMMARY Old male rats of 22–24 months and young ones of 3–5 months were studied to find the effects of ageing, of orchidectomy and of orchidectomy and treatment with testosterone propionate (TP) on the basal serum concentrations of thyrotrophin (TSH) and on the total and free concentrations of tri-iodothyronine (T3) and thyroxine (T4) in the serum. The changes in TSH after treatment with thyrotrophin releasing hormone (TRH) were also observed. Intact old rats had significantly (P < 0·001) lower basal T4 and T3 as well as lower (P < 0·05) testosterone concentrations than were present in young rats. They also had higher basal TSH and per cent free T4 but lower absolute free T3 concentrations than had young rats. Two weeks after orchidectomy, basal TSH concentrations were slightly but significantly (P < 0·05) decreased in both young and old rats while T4 decreased significantly (P < 0·05) only in the young. The responses of TSH to TRH were also reduced by orchidectomy in both age groups with the old rats being less responsive than the young. Orchidectomy and treatment with pharmacological doses of TP produced similar effects on the pituitary-thyrotrophic response for both old and young rats but a greater effect occurred in the basal T4 response in young rats. In all groups basal TSH was influenced by orchidectomy or by treatment with TP but was always higher in the aged rat. Tri-iodothyronine concentration was always lower in the older rat and was not altered by orchidectomy or by treatment with TP in either young or old rats. These results indicate that (1) in the male rat these age-specific effects on the thyroid–pituitary system are probably due, not only to a reduction in thyroid gland function and plasma T4 protein-binding, but also to a concomitant hyporesponsiveness of the aged male rat pituitary thyrotroph to TRH stimulation and (2) there is probably a significant influence of testicular function on the pituitary–thyroid system of the male rat.

DEVELOPMENTAL CHANGES IN THE DEGRADATION OF THYROTROPHIN RELEASING HORMONE BY THE SERUM AND BRAIN TISSUES OF THE MALE RAT

1977 ◽  
Vol 74 (2) ◽  
pp. 339-340 ◽  
Author(s):  
C. OLIVER ◽  
C. R. PARKER ◽  
J. C. PORTER
Keyword(s):  
Medical School ◽  
Developmental Changes ◽  
Male Rats ◽  
Male Rat ◽  
Obstetrics And Gynecology ◽  
Adult Rats ◽  
Thyrotrophin Releasing Hormone ◽  
Releasing Hormone ◽  
Old Rats ◽  
Phosphate Buffered Saline

*Laboratoire de Médecine Expérimentale, UER Médecine Nord, Boulevard Pierre Dramard, 13326 Marseille Cedex 3, France and †Department of Obstetrics and Gynecology, Southwestern Medical School, 5323 Harry Hines Boulevard, Dallas, Texas 75235, U.S.A. (Received 15 March 1977) Thyrotrophin releasing hormone (TRH) is rapidly degraded when incubated at 37 °C with plasma (Redding & Schally, 1969) or brain homogenates (Bassiri & Utiger, 1974) from adult rats. However, immunoreactive TRH is stable in serum obtained from rats less than 2 weeks old (Oliver, Taurog & Porter, 1974). No loss of biological or immunological TRH activity occurs during incubation with serum from 4- or 16-day-old rats (Neary, Kieffer, Federico, Mover, Maloof & Soodak, 1976). In this report, we have determined the TRH degrading activity of brain homogenates and serum obtained from male rats at various stages of development after birth. Synthetic TRH (1 ng, Beckman Instruments, Inc.) diluted in 50 μl phosphate-buffered saline (0·01

scholarly journals Aging and acute exercise enhance free radical generation in rat skeletal muscle

1999 ◽  
Vol 87 (1) ◽  
pp. 465-470 ◽  
Author(s):  
J. Bejma ◽  
L. L. Ji
Keyword(s):  
Skeletal Muscle ◽  
Lipid Peroxidation ◽  
Acute Exercise ◽  
Muscle Protein ◽  
Vastus Lateralis ◽  
Age Groups ◽  
Protein Carbonyl ◽  
Biological Aging ◽  
Young Rats ◽  
Old Rats

Reactive oxygen species (ROS) are implicated in the mechanism of biological aging and exercise-induced oxidative damage. The present study examined the effect of an acute bout of exercise on intracellular ROS production, lipid and protein peroxidation, and GSH status in the skeletal muscle of young adult (8 mo, n = 24) and old (24 mo, n = 24) female Fischer 344 rats. Young rats ran on a treadmill at 25 m/min and 5% grade until exhaustion (55.4 ± 2.7 min), whereas old rats ran at 15 m/min and 5% grade until exhaustion (58.0 ± 2.7 min). Rate of dichlorofluorescin (DCFH) oxidation, an indication of ROS and other intracellular oxidants production in the homogenate of deep vastus lateralis, was 77% ( P < 0.01) higher in rested old vs. young rats. Exercise increased DCFH oxidation by 38% ( P < 0.09) and 50% ( P < 0.01) in the young and old rats, respectively. DCFH oxidation in isolated deep vastus lateralis mitochondria with site 1 substrates was elevated by 57% ( P < 0.01) in old vs. young rats but was unaltered with exercise. Significantly higher DCFH oxidation rate was also found in aged-muscle mitochondria ( P < 0.01), but not in homogenates, when ADP, NADPH, and Fe3+ were included in the assay medium without substrates. Lipid peroxidation in muscle measured by malondialdehyde content showed no age effect, but was increased by 20% ( P < 0.05) with exercise in both young and old rats. Muscle protein carbonyl formation was unaffected by either age or exercise. Mitochondrial GSH/ GSSG ratio was significantly higher in aged vs. young rats ( P < 0.05), whereas exercise increased GSSG content and decreased GSH/GSSG in both age groups ( P < 0.05). These data provided direct evidence that oxidant production in skeletal muscle is increased in old age and during prolonged exercise, with both mitochondrial respiratory chain and NADPH oxidase as potential sources. The alterations of muscle lipid peroxidation and mitochondrial GSH status were consistent with these conclusions.

EFFECTS OF AGE AND OVARIAN FUNCTION ON THE PITUITARY–THYROID SYSTEM IN FEMALE RATS

1978 ◽  
Vol 78 (2) ◽  
pp. 225-232 ◽  
Author(s):  
H. J. CHEN ◽  
P. G. WALFISH
Keyword(s):  
Ovarian Function ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Lower Percentage ◽  
Female Rat ◽  
Thyrotrophin Releasing Hormone ◽  
Young Rats ◽  
Trh Stimulation ◽  
Old Rats ◽  
Absolute Concentrations

SUMMARY The effects of ovariectomy and ovariectomy and treatment with oestradiol benzoate (OB) on the basal concentration of thyrotrophin (TSH), the total concentrations and concentrations of free tri-iodothyronine (T3) and thyroxine (T4), and the concentrations of TSH, T3 and T4 observed after treatment with thyrotrophin releasing hormone (TRH) were studied in old (16–17 months of age) constant oestrous and young (3–4 months of age) oestrous rats. The untreated old control rats had significantly (P< 0·001) lower basal total T4 concentrations and percentage and absolute concentrations of free T4 and lower percentage and absolute concentrations of free T3 than untreated young rats. The basal levels of TSH in these two groups were similar and the increases in TSH after injection of TRH were identical. Two weeks after ovariectomy, no significant additional differences in hormone concentrations between old and young rats were observed. However, release of TSH induced by TRH was increased by three- to fourfold in old rats after ovariectomy compared with nine- to tenfold in young ovariectomized rats (P<0·01). Basal T4 concentrations remained unchanged in old ovariectomized rats treated for 7 days with 2 μg OB/day compared with both intact and ovariectomized rats. However, T4 concentrations in OB-treated young rats were significantly (P<0·001) reduced. Treatment with OB significantly increased both basal and TRH-induced T3 and TSH levels in old and young rats although the young rats showed a greater response (P<0·001). Two hours after injection of TRH, serum T3 concentrations in old rats increased only after OB treatment and not after ovariectomy alone or in intact rats, whereas T3 concentrations rose in all three groups of young animals. These results indicate that (1) older female rats have lower total T4, free T4 and free T3 concentrations and a lower TSH response to TRH, (2) OB treatment in young rats suppresses serum T4 but increases serum T3 and results in a greater TSH response to TRH and (3) at least one of the mechanisms accounting for the alterations in thyroid function observed in the older female rat, in addition to possible concomitant primary thyroid gland hypofunction, is a hyporesponsiveness of pituitary thyrotrophs to both endogenous negative feedback signals from low serum thyroid hormone concentrations and exogenous TRH stimulation.

scholarly journals P0529THE DIFFERENCE IN DIETARY RESTRICTION-INDUCED NEPHROPROTECTIVE MECHANISMS IN YOUNG AND OLD ANIMALS

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Nadezda Andrianova ◽  
Ljubava Zorova ◽  
Irina Pevzner ◽  
Vasily Popkov ◽  
Denis Silachev ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Dietary Restriction ◽  
Kidney Tissue ◽  
Kidney Injury ◽  
Male Rats ◽  
Kidney Cells ◽  
Lipid Peroxidation Products ◽  
Kidney Slices ◽  
Young Rats ◽  
Old Rats

Abstract Background and Aims Acute kidney injury (AKI) is a widespread disease affecting mostly old people. Dietary restriction (DR), based on the reduction of food intake, is believed to be one of the most efficient approaches ameliorating damage in different pathological conditions including age-associated diseases. The aim of the study was to investigate the protective mechanisms of DR in the model of AKI in young and old rats. Method All experiments were made on young (3-4 months) and old (22-24 months) male rats. DR was performed by limiting the amount of food for 35% of the ad libitum (AL) daily intake. Since earlier, we showed ineffectiveness of 4-weeks DR in old rats, in this study we applied 35% DR lasting 8 weeks for old rats and 4 weeks for young rats. During DR, we registered the weight loss and measured the level of adiponectin, as this hormone is closely associated with adipose tissue metabolism. Renal ischemia/reperfusion (I/R) was used as a model of ischemic AKI. I/R was performed by clamping the left renal pedicle for 40 minutes followed by reperfusion with simultaneous contralateral nephrectomy. The severity of AKI was evaluated by measuring blood urea nitrogen (BUN), serum creatinine (SCr) and the levels of protein biomarkers of AKI (NGAL and L-FABP) in urine. Proliferation in kidney epithelium in response to I/R was analyzed by PCNA protein level in kidney tissue. We evaluated the function of mitochondria by measuring TMRE/MitoTracker Green ratio in vital kidney slices; in kidney homogenates, we also analyzed levels of Bcl-XL and Bcl-XS proteins. The production of reactive oxygen species (ROS) was evaluated by staining vital kidney slices with DCF. The content of lipid peroxidation products was measured using Image-iT Lipid Peroxidation Kit, and the level of carbonylated proteins was determined by OxyBlot Protein Oxidation Detection Kit. The activation of autophagic-lysosomal system was estimated by western blotting to LC3 II/LC3 I ratio and LAMP1 level, as well as by staining vital kidney slices with LysoTracker Green probe. Results The body weight of rats during DR dropped as far as 20% by the end of 4 weeks in young rats and 30% by the end of 8 weeks in old rats. Nevertheless, adiponectin concentration elevated during DR only in the serum of young rats. DR strongly influenced mitochondria function, in particular, elevated mitochondrial membrane potential both in kidney cells of young and old rats. DR also resulted in increasing the Bcl-XL level. We revealed the decrease of ROS and lipid peroxidation products in vital kidney slices, but only in kidneys of young rats. However, DR reduced the content of carbonyl groups more than 2 times in animals of both ages. We showed that activation of autophagy in response to DR and I/R occurred only in the kidneys of young rats, indicating deterioration of autophagy signaling in old animals. We also found that 48 h after I/R PCNA level increased 19 times in young kidney, although old rats showed only 4-fold elevation of kidney cells proliferation. Estimation of kidney injury markers (NGAL, L-FABP) in urine revealed that 2-month DR led to some protection in old rats. Nonetheless, despite all positive alterations in kidney tissue of old rats, DR was not able to ameliorate impairment of kidney function after I/R, whereas all young rats showed significant improvement of SCr and BUN levels. Conclusion Short-term DR has a significant nephroprotective effect against renal I/R in young rats. Old animals require longer periods of food restriction, after which some protective alterations are observed. We propose, protection of kidney in old and young rats is implemented through slightly different mechanisms and some of them are missing in old animals.

Effect of short-term starvation on reproductive hormone gene expression, secretion and receptor levels in male rats

1989 ◽  
Vol 121 (3) ◽  
pp. 409-417 ◽  
Author(s):  
M. Bergendahl ◽  
A. Perheentupa ◽  
I. Huhtaniemi
Keyword(s):  
Male Rats ◽  
Ventral Prostate ◽  
Male Rat ◽  
Testicular Function ◽  
Mrna Levels ◽  
Short Term ◽  
Α Subunit ◽  
Gnrh Receptors ◽  
Androgen Synthesis ◽  
Serum Lh

ABSTRACT The effects of 4–6 days of food deprivation on the pituitary-testicular function of adult male rats were studied. Fasting decreased body weights on average by 23% (P<0·01) and those of seminal vesicles by 55% (P<0·01) in 4 days. No consistent changes were found in testicular and ventral prostate weights. The pituitary levels of gonadotrophin-releasing hormone (GnRH) receptors decreased by 50% (P<0·01). Serum and pituitary levels of LH, FSH and prolactin decreased by 25–50% (P<0·01 for all). Testicular and serum levels of testosterone decreased by 70–80%, testicular LH receptors by 26%, those of prolactin by 50% (P<0·01 for all), but those of FSH remained unaffected. Acute (2 h) stimulation by a GnRH agonist (buserelin, 10 μg/kg i.m.) resulted in similar LH, FSH and testosterone responses in the fasted and control animals, and human chorionic gonadotrophin (hCG) stimulation (30 IU/kg i.m.) in similar increases in testosterone. A 42% decrease was found in pituitary content of mRNA of the common α subunit (P<0·05), but the mRNAs of the LH- and FSH-β chains and prolactin were unaffected by fasting for 4 days. When the same mRNAs were measured after 6 days of fasting, the decrease of the mRNA of FSH-β also became significant (50%, P<0·01). In contrast, the mRNA of LH-β was increased twofold (P<0·01) at this time and serum LH levels were similar in control and starved animals. It is concluded that during short-term starvation of male rats: (1) the decrease in gonadotrophin and prolactin synthesis and secretion is first noticed on the level of translation (protein synthesis), and the mRNA levels of these hormones may respond more slowly to starvation, (2) decreased pituitary GnRH receptors indicate decreased GnRH release from the hypothalamus, (3)the gonadotrophin and prolactin loss results secondarily in decreased testicular androgen synthesis and LH and prolactin receptor levels, (4) no decrease occurs during starvation in acute gonadotrophin response to GnRH, or testicular testosterone response to hCG, (5) the primary response to starvation in male rat pituitary-testicular function is the loss of normal hypothalamic support of gonadotrophin and prolactin secretion, rather than direct nutritional effects on the pituitary and testis, and (6) when starvation is continued beyond 4 days, a recovery is seen in pituitary mRNA on the LH-β chain and in serum LH, most probably because the starvation-associated decrease serum testosterone is a more potent positive stimulus of LH synthesis than the direct hypothalamic-pituitary inhibition. Journal of Endocrinology (1989) 121, 409–417

scholarly journals Thyroid function and aging: gender-related differences

2001 ◽  
Vol 171 (1) ◽  
pp. 193-198 ◽  
Author(s):  
VM da Costa ◽  
DG Moreira ◽  
D Rosenthal
Keyword(s):  
Thyroid Gland ◽  
Thyroid Function ◽  
Gonadal Hormones ◽  
Female Rats ◽  
Male Rats ◽  
Type I ◽  
Iodothyronine Deiodinase ◽  
Thyroid Gland Function ◽  
Gland Function ◽  
Rat Thyroid

The effects of aging on human or animal thyroid function are still not well defined. We evaluated some aspects of thyroid function during aging using an animal model (young and old Dutch-Miranda rats). In old rats of both genders, serum thyroxine (T4) decreased but serum thyrotrophin (TSH) remained unaltered, suggesting a disturbance in the pituitary-thyroid feedback mechanism during aging. Serum tri-iodothyronine (T3) only decreased in old males, possibly because female rats are almost twice as efficient in hepatic T4 to T3 deiodination. Thyroidal T4-5'-deiodinase activity did not change much during aging, although it decreased slightly in males. Thyroidal iodothyronine-deiodinase type I mRNA expression but not total thyroidal enzymatic activity were higher in female than in male rats. Thus, ovarian/testicular hormones may modulate the expression and/or the activity of hepatic and thyroidal type I iodothyronine-deiodinase. Thyroperoxidase (TPO) and thyroglobulin (Tg) expression were higher in young male rats than in females. In males, TPO and Tg gene expression decreased with aging, suggesting that androgens might increase their expression. Our results showed that aging induces real changes in rat thyroid gland function and regulation, affecting at least pituitary, thyroid and liver functions. Furthermore, some of these changes were gender related, indicating that gonadal hormones may modulate thyroid gland function and regulation.

Effect of pinealectomy and melatonin treatment during pregnancy on the sexual development of the female and male rat offspring

1995 ◽  
Vol 132 (6) ◽  
pp. 765-770 ◽  
Author(s):  
B Díaz López ◽  
MD Colmenero Urquijo ◽  
ME Díaz Rodriguez ◽  
A Arce Fraguas ◽  
A Esquifino Parras ◽  
...  
Keyword(s):  
Sexual Development ◽  
Female Offspring ◽  
The Other ◽  
Male Rats ◽  
Male Rat ◽  
Plasma Prolactin ◽  
Melatonin Treatment ◽  
Control Male ◽  
Rat Offspring ◽  
Old Rats

Díaz López B, Colmenero Urquijo MD, Díaz Rodriguez ME, Arce Fraguas A, Esquifino Parras A, Marín Fernández B, Effect of pinealectomy and melatonin treatment during pregnancy on the sexual development of the female and male rat offspring. Eur J Endocrinol 1995;132:765–70. ISSN 0804–4643 Sexual development of female and male rat offspring of control, pinealectomized (PIN-X) or melatonin (MEL 2 50 μg/100 g body wt)-treated mother rats during pregnancy was studied. Newborns were studied at the following phases of sexual development: neonate (5 days old), infantile (15 days old), juvenile (25 and 30 days old) and pubertal phase (55 days). In female offspring, MEL treatment during pregnancy significantly increased plasma luteinizing hormone (LH) in 15- and 25-day-old rats; however, at the end of the prepubertal period (30 days) the concentration of plasma LH decreased significantly as compared to control rats. This hormonal pattern was different from that observed in offspring of control and PIN-X rats, which had low LH levels at 25 days of age and higher LH levels at 30 days of age. Follicle-stimulating hormone (FSH) did not vary significantly among the three groups. Plasma prolactin levels were affected by PIN-X of the mother, showing significantly higher levels in the 5-day-old offspring than in the controls; plasma prolactin levels were also affected by MEL treatment of the mother, producing hyperprolactinemia in the 30-day-old female offspring. In male offspring, sexual development in control male rats progressed rapidly with significantly increased LH and FSH levels at 25 and 30 days compared to those measured during the neonatal and infantile periods. Pinealectomy of the mother induced the following modifications: in 5-, 15- and 30-day-old male rats, decreased LH levels were measured relative to the other two groups studied in 5- and 25-day-old rats, significantly lower FSH levels than in the control rats were recorded. However, in 5- and 15-day-old rats, significantly higher prolactin levels than in control rats were measured. Melatonin injections during pregnancy decreased FSH levels at 5, 25, 30 and 55 days as compared to the control males. Also, MEL increased LH levels in 25-day-old rats and significantly decreased prolactin levels in 15- and 55-day-old rats as compared to the other two groups. These results indicate that the mother's pineal gland and MEL treatment can act on fetal development and influence the postnatal ontogeny of the hormones involved in the neuroendocrine–reproductive axis in developing rats. The effect of MEL was apparent during pubertal stages of the offspring, while the effect of PIN-X was more apparent during the juvenile period of the young rats. Beatriz Díaz López, Dpt. Biología Funcional, Arca Fisiología, Fac, Medicina, Universidad de Oviedo, 33006-Oviedo, Spain

Pharmacological effects of the continuous administration of an LHRH agonist in the ageing male rat: comparison with orchidectomy

1990 ◽  
Vol 124 (2) ◽  
pp. 261-NP ◽  
Author(s):  
Y. Amir-Zaltsman ◽  
Y. Ausher ◽  
B. Gayer ◽  
S. Lichter ◽  
F. Serour ◽  
...  
Keyword(s):  
Tissue Response ◽  
Continuous Treatment ◽  
Male Rat ◽  
Moderate Increase ◽  
Lhrh Agonist ◽  
Pharmacological Effects ◽  
Young Rats ◽  
Age Related ◽  
Ageing Male ◽  
Old Rats

ABSTRACT The age-related changes in tissue response to chronic treatment for 1 month with a potent LHRH agonist were investigated in the ageing male rat, and the observed pharmacological effects were compared with orchidectomy. In both young (4 months) and old (22 months) rats, treatment resulted in a significant decrease in the weights of prostates and testes, a decrease in plasma LH and testosterone levels, a loss of LH receptors in the testes and in a complete depletion of prostatic nuclear androgen receptors, reaching levels observed after castration. In young rats, treatment with an LHRH agonist or orchidectomy induced a three- or sixfold increase in prostatic creatine kinase (CK) activity which may have been induced by the local stimulatory effect of oestradiol arising from the conversion of precursor steroids secreted by the adrenal. On the other hand, in old rats, 7 days after orchidectomy or after treatment with an LHRH agonist a twofold increase or no change was induced in prostatic CK activity respectively. SDS gel electrophoresis patterns of cytosolic prostatic proteins of young rats treated with an LHRH agonist or young rats orchidectomized 7 days previously revealed the presence of several intensified proteins, two of them having apparent molecular weight of 67 kDa and 43 kDa, whereas in the old rats treated with LHRH agonist or old rats castrated 7 days previously, these two proteins were not intensified. The results of this study confirmed that continuous treatment with an LHRH agonist to young and old rats induces medical castration since the pharmacological effects observed were the same as those induced with surgical castration. However, in the old rats, the lack of an increase in prostatic CK activity upon treatment with LHRH agonist, and the moderate increase in CK activity upon orchidectomy, suggest that prostatic cells in older rats have decreased sensitivity to hormonal manipulation. Journal of Endocrinology (1990) 124, 261–268

Aging alters neuronal nitric oxide release from rat mesenteric arteries: role of presynaptic β-adrenoceptors

2001 ◽  
Vol 101 (4) ◽  
pp. 321-328 ◽  
Author(s):  
Mercedes FERRER ◽  
Gloria BALFAGÓN
Keyword(s):  
Nitric Oxide ◽  
Age Groups ◽  
Electrical Field Stimulation ◽  
Mesenteric Arteries ◽  
Induced Response ◽  
Young Rats ◽  
No Release ◽  
Old Rats ◽  
Na Release ◽  
Subsequent Addition

This study examines the influence of aging on the neuronal nitric oxide (NO) and noradrenaline (NA) release elicited by electrical field stimulation (EFS; 200 mA, 0.3 ms, 1-16 Hz, 30 s) in endothelium-denuded mesenteric arteries from young and old rats, as well as the influence of the presynaptic β-adrenoceptors in that release. EFS induced frequency-dependent contractions. NG-nitro-l-arginine methyl ester (l-NAME) only enhanced EFS-elicited contractions in arteries from young rats. Capsaicin did not alter the EFS-induced contractions in either age group. Clenbuterol did not modify the contraction elicited by EFS in arteries from young or old rats either. A subsequent addition of l-NAME also induced an increase in the EFS-induced response in arteries from both age groups. In old rats, the presence of propranolol did not alter the response induced by EFS, and the subsequent addition of clenbuterol or clenbuterol plus l-NAME did not affect this response. In precontracted segments, sodium nitroprusside or clenbuterol induced similar relaxation in both age groups. None of the drugs used altered the response to exogenous NA or basal tone. In arteries preincubated with [3H]NA, EFS induced 3H release, which remained unmodified in the presence of clenbuterol or propranolol in young rats, whereas clenbuterol increased the 3H overflow in old rats, and this effect was abolished by propranolol. These drugs did not alter the basal 3H efflux and indicate that in rat mesenteric arteries EFS induces NA release in both age groups, and only NO release in young animals. Activation of presynaptic β-adrenoceptors increased NA and probably NO release in aged rats.

GONADOTROPHINS, TESTOSTERONE AND SPERMATOGENESIS IN NEONATALLY IRRADIATED MALE RATS: EVIDENCE FOR A ROLE OF THE SERTOLI CELL IN FOLLICLE-STIMULATING HORMONE FEEDBACK

1977 ◽  
Vol 75 (2) ◽  
pp. 209-219 ◽  
Author(s):  
F. H. DE JONG ◽  
R. M. SHARPE
Keyword(s):  
Sertoli Cell ◽  
Sertoli Cells ◽  
Age Groups ◽  
Male Rats ◽  
Male Rat ◽  
Postnatal Life ◽  
Spermatogenic Cells ◽  
Normal Numbers ◽  
Testicular Cell

Peripheral concentrations of FSH in the male rat seem to be regulated in part by a protein hormone, inhibin, which originates from the testes. In an attempt to ascertain which type of testicular cell secretes inhibin, groups of male rats were irradiated prenatally or on days 4, 6 or 8 of postnatal life, and killed at 21, 51 or 81 days of age together with castrated and intact controls. The concentrations of FSH and LH in the pituitary gland, and FSH, LH and testosterone in the plasma were estimated for each animal, and the numbers of each class of intratubular cell in the testes were calculated. Rats irradiated neonatally had fewer Sertoli cells than controls at all ages studied, while the numbers of Sertoli cells in rats irradiated prenatally were higher than those in controls on day 21. The number of spermatogenic cells was usually decreased in rats irradiated postnatally. In the rats irradiated prenatally normal numbers of spermatogenic cells were found at day 51. Numbers of spermatogenic cells were significantly correlated with the number of Sertoli cells at the ages of 51 and 81 days. The concentration of FSH in the plasma usually increased in the postnatally irradiated animals on days 21 and 51, but not on day 81; prenatal irradiation did not result in altered levels of FSH at any age. Peripheral levels of LH and testosterone were not affected by irradiation. The concentration of FSH in the plasma was negatively correlated with the number of Sertoli cells in all age groups, whereas significant correlations between the level of FSH and the number of spermatogenic cells were only found at days 51 and 81. It is concluded from these data that the Sertoli cell is the most likely source of inhibin.

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