Biomedical subjects

R Pierantoni

Publications and source records attributed to R Pierantoni.

At least 55 records · Page 3Linked to original sources

PubMed1990

Characterization of gonadotropin-releasing hormone (GnRH) binding sites in the pituitary and testis of the frog, Rana esculenta.

Frog, Rana esculenta, pituitary and testis gonadotropin-releasing hormone (GnRH) receptors were characterized by using 125I-chicken IIGnRH (cIIGnRH) as radiolabeled ligand. At 4 C equilibrium binding of 125I-cIIGnRH to pituitary homogenates was achieved after 90 min of incubation; binding of 125I-cIIGnRH to testis membrane fractions reached its maximum at 60 min of incubation. Binding of the radioligand was a function of tissue concentration, with a positive correlation over the range 0.5-2 tissue equivalents per tube. One pituitary and one testis per tube were used as standard experimental condition. Incubation of the pituitary homogenate with increasing concentrations of 125I-cIIGnRH indicated saturable binding at radioligand concentrations of 1 nM and above while for the testis membrane preparation saturation was achieved using 5 nM 125I-cIIGnRH. The binding of 125I-cIIGnRH was found to be reversible after addition of the cold analog and the displacement curves could be resolved into one linear component for both tissues. Scatchard analysis suggested the presence of one class of binding sites for both pituitary and testis (Pituitary: Kd = 1.25 +/- 0.14 nM and Bmax = 8.55 +/- 2.72 fmol/mg protein; testis: Kd = 2.23 +/- 0.89 nM and Bmax = 26.48 +/- 7.39 fmol/mg protein). Buserelin displaced the labeled 125I-cIIGnRH with a lower IC50 as compared with cIIGnRH cold standard, while Arg-vasopressin (AVP) was completely ineffective, confirming the specificity of binding.

Amino Acid Sequence↗

PubMed1990

Morphological and hormonal changes in the frog, Rana esculenta, testis after administration of ethane dimethane sulfonate.

Apart from mice, in rodents ethane dimethane sulfonate (EDS) selectively destroys Leydig cells. This has been indicated as a new method for the study of seminiferous interstitial compartment interaction. No information on the possible destruction and repopulation of Leydig cells exists in lower vertebrates. This study deals with EDS effects in the frog, Rana esculenta. Animals received a single intraperitonial dose (100 mg/kg body wt) and were sacrificed at 0, 12, and 24 hr and 3, 4, 7, 14, and 28 days postinjection. Androgens (testosterone + DHT) were measured in plasma and right testes. Moreover, left testes were fixed and examined for histological observation. Plasma androgen levels were extremely low on Day 4 after EDS treatment and remained unchanged thereafter. In testes, androgen levels decreased on Day 4 but increased to control levels on Day 14. Leydig cells were damaged within 3 days post-treatment and were completely destroyed on Days 4 and 5. Germinal compartment damage appeared only where the adjacent interstitial tissue presented complete destruction. Pale primary spermatogonia (stem cells) were always present. Testes restored to normal on Day 14 and spermatogenesis resumed to the regenerating interstitial tissue. These results show that regenerating testes in R. esculenta retain androgens and that interstitial-germinal compartment communications may have a role in maintaining spermatogenesis.

Androgens↗

PubMed1990

Indirect evidence for a physiological role exerted by a "testicular gonadotropin-releasing hormone" in the frog, Rana esculenta.

The possible physiological role of a putative testicular gonadotropin-releasing hormone (GnRH)-like material was studied in the frog, Rana esculenta. We have investigated (a) changes of mitotic index (MI) of primary spermatogonia (SPG) in GnRH agonist (GnRH-Ag)-treated testes in vitro; (b) changes of androgen concentrations in testes of intact frogs treated with a GnRH antagonist (GnRH-Ant); (c) variations of mitotic index of primary SPG in intact GnRH-Ant-injected animals and in testes incubated with GnRH-Ant; (d) changes of MI in hypophysectomized (PDX) animals treated with hypophysis (PD) homogenate, and hCG alone or in combination with GnRH-Ant; and (e) changes of androgen concentrations in plasma PDX frogs treated with hCG and hCG plus GnRH-Ant. Our results indicate that while GnRH-Ag induced accumulation of primary SPG mitosis, GnRH-Ant inhibited androgen production and natural occurring mitosis accumulation. Therefore, GnRH-Ant may counteract an endogenous peptide working into the testis.

Androgens↗

PubMed1990

Regulation of the testicular activity in the marine teleost fish, Gobius paganellus.

Seasonal variations of intratesticular steroid hormones (androgens and estradiol-17 beta) and spermatogenic activity have been studied in the marine teleost fish, Gobius paganellus. In addition, in vivo and in vitro experiments have been carried out in order to investigate the control of androgen production by the testis. While estradiol was never detected, androgens were at low values in autumn and reached maximal levels in spring concomitantly with the highest testis weight and the highest efficiency of the spermatogenic wave. In vitro incubations were carried out using ovine luteinizing hormone (oLH) (400, 4000, and 40,000 micrograms/liter; 20 degrees for 6 and 24 hr). The effective dose 40,000 micrograms/liter was used to induce androgen stimulation in both autumn and spring testes. The responsiveness to oLH was enhanced in spring testis. Estradiol and a gonadotropin-releasing hormone analog GnRHA (HOE766) were ineffective in modulating androgen production either alone (1-1000 nmol/liter) or in concert with oLH during short-term incubations. In intact animals, GnRHA elicited, 3 hr after the injection (10 micrograms), a three-fold increase of intratesticular androgen content. In conclusion, we show that the annual androgen profile in G. paganellus parallels the spermatogenic activity and that the androgen production is not affected in these experimental conditions by putative intratesticular factors (e.g., estradiol-17 beta and GnRH-like substances) which, conversely, are effective in inducing androgen changes in several vertebrate species.

Androgens↗

PubMed1989

A gonadotropin releasing hormone analog induces spermiation in intact and hypophysectomized frogs, Rana esculenta.

The sperm-releasing activity of a gonadotropin releasing hormone (GnRH) agonist, Buserelin (GnRH) and hypophysis homogenate (PD) preparations was studied in intact and hypophysectomized (PDX) frogs, Rana esculenta. In addition, human chorion gonadotropin (hCG) was tested in PDX animals, and GnRH antagonist (GnRHA) treatments were carried out in intact and PDX animals, in combination with the hormonal injections. GnRH or PD treatments were able to elicit spermiation in intact and PDX animals. While GnRH, injected 24 h later, was again effective in inducing spermiation in intact animals, this was not the case in PDX frogs. GnRHA counteracted GnRH effects in intact frogs. Moreover, in PDX animals GnRHA injections counteracted the sperm-releasing activity induced by hCG or GnRH, but failed to inhibit sperm-releasing activity induced by PD homogenate.

Animals↗

PubMed1989

Seasonal fluctuations of estrogen-binding activity in the testis of the frog, Rana esculenta.

We have studied the annual cycle of estrogen-binding activity in the frog, Rana esculenta, testis to evidence possible fluctuations. The testicular binding for [3H]estradiol-17 beta shows high affinities (cytosolic Kd = 1.94 +/- 0.43 x 10(-9) M; nuclear Kd = 2.72 +/- 1.20 x 10(-9) M) and low capacity (cytosolic: 7.56 +/- 0.66 fmol/mg protein; nuclear: 9.27 +/- 2.5 fmol/mg protein). Nuclear-binding activity appears in spring concomitantly with the estradiol peak in plasma and testes, while, in the remaining periods, binding capacity was extremely low or absent. Present data strongly support an important role played by estrogens as an intratesticular control factor in vertebrates.

Animals↗

PubMed1989

Intratesticular feedback mechanisms in the regulation of steroid profiles in the frog, Rana esculenta.

Testosterone (T), 5 alpha-dihydrotestosterone (DHT), estradiol-17 beta (E), and progesterone (P) were measured in the plasma of the frog, Rana esculenta, during the annual cycle. Moreover, in vitro experiments were carried out in order to investigate the local regulation of steroidogenesis. Testosterone and DHT showed high values during autumn and early spring and had a T/DHT ratio which increased during summer, while E peaked in midspring, remaining at detectable values thereafter. Progesterone increased in autumn, winter, and spring. In vitro incubations of minced testes showed that E, stimulated by pituitary factors, inhibited androgen synthesis while T did not. Our results indicate that paracrine and/or autocrine mechanisms operate in the frog testis to regulate annual steroid profiles.

Animals↗

PubMed1989

Molecular forms of immunoreactive gonadotropin-releasing hormone in hypothalamus and testis of the frog, Rana esculenta.

The hypothalamus and the testis of the frog, Rana esculenta, contain gonadotropin-releasing hormone (Gn-RH)-like peptides which are recognized by an antiserum raised against mammalian Gn-RH. Two molecular forms which coelute with synthetic chicken II and salmon Gn-RH from reverse-phase HPLC were distinguished in the hypothalamus. A single peak coeluting with synthetic chicken II Gn-RH was present in the testis.

Animals↗

PubMed1989

Effects of intratesticular injections of estradiol and gonadotropin-releasing hormone (GnRHA, HOE 766) on plasma androgen levels in intact and hypophysectomized Torpedo marmorata and Torpedo ocellata.

The effect of a gonadotropin-releasing hormone analog (GnRHA, HOE766) was studied in hypophysectomized elasmobranch fish Torpedo marmorata and T. ocellata. In addition, estradiol (E2) effects were studied in intact and hypophysectomized (HPX) animals. Plasma androgen concentrations were measured 2 or 6 hr after GnRHA (100 ng or 10 micrograms) or 6 hr after E2 (10(-9) or 10(-6) M) intratesticular injections. Both GnRHA and E2 induced the increase of plasma androgen levels in HPX fish. E2 also enhanced androgen levels in intact animals. It is concluded that GnRH-like substances and E2 may modulate testicular activity in elasmobranch fish.

Androgens↗

PubMed1989

[Continuous localized EEG discharges during sleep in children].

Continuous generalized spike-and-wave complexes occurring during slow-sleep were first observed in some children by Patry et al. (1971). A general review of the reported cases was made by Tassinari et al. (1984). We have observed a new clinical-EEGraphic picture. Spikes and spike-and-wave complexes localized to one hemisphere were recorded during at least 85% non-REM sleep both in 3 quadriplegic and in 3 hemiplegic mentally retarded children, aged from 2 years and 10 months to 11 years (mean age: 5 years and 2 months). Cyclic organization of sleep was almost normal. Wake EEG showed an epileptic focus. Brain CT showed midline defect and brain atrophy in quadriplegic patients, and a wide temporal-parietal porencephalic cyst in hemiplegic patients. This EEGraphic pattern was associated with a more pronounced mental impairment: neuropsychological improvement was observed in 2 cases, when continuous sleep discharges disappeared. As aforesaid, this picture seems to be related either to hemispheric or to midline brain defects. In our cases, sleep phase organization could be examined, while continuous generalized discharges occurring during sleep do not allow such a study.

Child↗

PubMed1988

Relationship between estradiol-17 beta seasonal profile and annual vitellogenin content of liver, fat body, plasma, and ovary in the frog (Rana esculenta).

The seasonal plasma estradiol-17 beta (E2-17 beta) profile and annual vitellogenin content of liver, fat body, plasma, and ovary were investigated in Rana esculenta. Concomitant with the increase in E2-17 beta, vitellogenin peaked in liver, plasma, and ovary during autumn and winter, while it remained at a relatively high concentration in fat body during spring. In vitro experiments showed that E2-17 beta (10(-9) M) is ineffective in inducing vitellogenin production in fat body, but is effective in inducing vitellogenin production in liver. As fat bodies do not produce the vitellogenin they contain, we suggest that fat bodies are involved in the transfer of vitellogenin to the ovary.

Animals↗

PubMed1988

Hypothalamus-hypophysis and testicular GnRH control of gonadal activity in the frog, Rana esculenta: seasonal GnRH profiles and annual variations of in vitro androgen output by pituitary-stimulated testes.

The binding of a gonadotrophin-releasing hormone (GnRH) long acting analog (GnRHA), D-Ser (But)6,Pro9-NEt GnRH (HOE 766), to pituitary and testicular extracts and the presence of GnRH-like material in testes and hypothalamuses were measured in the frog, Rana esculenta. Also, the cellular localization of immunoreactive GnRH was investigated in testes by immunohistochemical staining. Furthermore, lyophilized preparations of pituitary crude homogenates from animals caught monthly were tested in vitro for their ability to stimulate androgen production by December testes. Satisfactory results on specific 125I-GnRH binding were difficult to obtain in view of its low binding capacity. Moreover, binding in testicular homogenates was of the same order of magnitude (about 2%) as that found in pituitaries. In a cospecific radioimmunoassay for GnRH nonapeptide, both hypothalamic and testicular extracts gave displacement parallel to the standard curve. Immunoreactive GnRH did not significantly fluctuate in hypothalamuses, while it peaked in testes during December and July. Immunoreactive GnRH was evidenced in June and September testes employing immunohistochemical staining. In particular, the interstitial cells and the Sertoli cells were faintly stained. Testes of December animals stimulated by February pituitaries produced larger quantities of androgens as compared with testes stimulated with hypophyseal preparations from the remaining periods of the year. In conclusion, the present results are consistent with the idea that seasonal changes of the hypothalamus-hypophyseal activity play an important role in regulating the hormonal response in vertebrate testes. Moreover, we report that, in addition to rats, GnRH-like material is present in frog testes and for the first time it has been shown that such putative intratesticular material undergoes seasonal fluctuations in a vertebrate.

Androgens↗

PubMed1988

Fat body involvement in vitellogenin fate in the green frog, Rana esculenta.

1. Since, in Rana esculenta, fat bodies contain vitellogenin, the present study was performed in order to determine whether or not fat bodies are involved in the fate of vitellogenin. 2. The experiment of November shows that fat body excision provokes plasma vitellogenin increase even in animals treated with estradion-17 beta + pituitary crude homogenate (as compared with relative control). The same picture has been shown in the April experiment. 3. The result on protein-bound phosphate in ovaries from the April experiment has shown that fat body extirpation causes a decrease of protein-bound phosphate in the ovary. 4. This results indicates that fat bodies play an important role in sequestrating circulating vitellogenin by the ovary.

Animals↗

PubMed1988

A gonadotropin-releasing hormone (GnRH) antagonist decreases androgen production and spermatogonial multiplication in frog (Rana esculenta): indirect evidence for the existence of GnRH or GnRH-like material receptors in the hypophysis and testis.

The effects of a GnRH antagonist (GnRHA) on GnRH agonist (GnRH*)-induced androgen production and spermatogonial multiplication were studied in the frog, Rana esculenta, in vivo and in vitro. Intact and hypophysectomized (PDX) animals were kept at 22 +/- 2 C and treated with GnRH (45 ng/g BW) and GnRH* plus 1X and 10X concentrations of GnRHA on alternate days for 2 weeks. Androgen concentration in GnRH* plus GnRHA-treated animals decreased in the testis by about 50% with the 10X dose whereas the increase obtained in GnRH*-treated PDX group was completely abolished with the 1X dose. Histological sections were evaluated with respect of the mitotic index (MI) of the primary spermatogonia. Both GnRHA-treated intact and PDX frogs showed a dose-dependent MI decrease which reached 59% and 57% of control, respectively. In vitro incubations were carried out on testis halves at 15 C for 0, 2, 4, 6, and 8 h with the addition of 1 microgram GnRH* and 1 microgram GnRH* plus 1 or 10 micrograms GnRHA. The stimulatory effect of GnRH* and the inhibitory effect of GnRHA were apparent within 2 h. The basal mitogenic activity was affected by antagonist treatment and the inhibitory effect on the MI was evident within 2-4 h in the 10X-treated groups or within 6-8 h in the 1X treated groups. Since GnRH* and GnRHA bind to the same receptor these data strongly indicate that the effects of putative GnRH-like materials in the frog, Rana esculenta, are mediated throughout stereospecific recognition sites in both pituitary and testis.

Androgens↗

PubMed1988

Seasonal fluctuations in plasma progesterone concentrations in Gentile-di-Puglia and Ile-de-France ewes in southern Italy.

Ile-de-France ewes had high plasma progesterone concentrations during early summer-late winter. Gentile-di-Puglia ewes had high progesterone values during the winter-spring-summer period but during autumn progesterone values were very low and oestrous behaviour was not displayed. The comparison with Ile-de-France ewes indicates that a phase shift occurs in the annual ovarian activity in ewes of the Gentile-di-Puglia breed.

Animals↗

PubMed1987

Annual testicular activity in the gray partridge (Perdix perdix L.).

Seasonal changes in plasma androgens, testicular total protein content, gonosomatic index, and spermatogenic activity were studied in the grey partridge, Perdix perdix. Moreover, testicular androgen output after stimulation with ovine LH (oLH) was tested in vitro during different periods of the sexual cycle. Androgens and the gonosomatic index peaked in April, during which all the spermatogenic stages were observed. Total protein content in the testes was highest in January and March. Gonadal responsiveness to oLH was found to increase in the period April-May in coincidence with the hormone peak in the plasma, while February testes were irresponsive.

Animals↗

PubMed1987

Seasonal plasma and intraovarian sex steroid profiles, and influence of temperature on gonadotropin stimulation of in vitro estradiol-17 beta and progesterone production, in Rana esculenta (Amphibia: Anura).

Seasonal plasma and intraovarian estradiol-17 beta (E) and progesterone (P) fluctuations were studied by specific radioimmunoassay in the frog, Rana esculenta. Moreover, incubations of ovine-luteinizing hormone (oLH)-stimulated ovarian pieces at two different temperatures (15 and 24 degrees) have been carried out in order to evaluate the dependence of E and P output on this exogenous factor. Estradiol showed similar changes in plasma and ovaries, while P profile was better evidenced in the gonads since this hormone fluctuated in plasma, giving pulses of difficult interpretation. A shift from E to P production by the ovary near the ovulatory period (February-March) was noted. In vitro experiments were carried out using approximately equal-sized ovarian fragments containing follicles ranging from 0.7 to 1 mm and classified as early vitellogenic. High temperature induced oLH-stimulated P production within 6 h, while E increased after 24 h concomitantly with a P decline. At 15 degrees the stimulatory effect of oLH was achieved only on E output in the incubation medium after 24 h. In conclusion, our results in the frog, R. esculenta, show that E and P intervene at peak values separately during the annual cycle and that the temperature has an important role in the regulation of the steroid hormone-releasing activity.

Animals↗

PubMed1986

Plasma sex hormone profile in Gentile di Puglia ewes during the estrus cycle.

The profiles of estradiol (E2), progesterone (P), and androstenedione (A), have been studied for the first time in cyclic Gentile di Puglia ewes. Estradiol peaks at estrus whereas progesterone levels are high during the luteal phase. Androstenedione does not show meaningful cyclic fluctuation. All hormones examined show also a pulsatile pattern when plasma was collected hourly.

Androstenedione↗