Changes in the testicular metabolism of dehydroepiandrosterone during the annual reproductive cycle of the hedgehog (Erinaceus europaeus L).

Testicular homogenates obtained from the hedgehog (Erinaceus europaeus L.) at different stages of its annual reproductive cycle were incubated with radioactive dehydroepian-drosterone as the substrate at 35 and 4.5° (hibernation temperature). Testosterone (T) and/or 5-androstene-3β,17β-diol (Δ⁵-A) were found as the main metabolites. In the incubations carried out in the absence of co-factors or in the presence of NADP the formation of Δ⁵-A dominated over that of T. In the presence of NADT was formed in high, and Δ⁵-A in negligible or undetectable amounts. The formation of both these steroids was clearly inhibited when the homogenates derived from hibernating animals were incubated at 4.5°. The nature of this cold-induced inhibition of steroidogenesis is discussed.     

Plasma testosterone binding protein capacity in relation to the annual testicular cycle in a hibernating mammal,the hedgehog (Erinaceus europaeus L.)

Plasma testosterone levels are measured by radioimmunoassay and plasma testosterone-binding protein activity (SBP) is determined by an equilibrium dialysis method in the male adult hedgehog, a hibernating mammal. Determinations are performed monthly during 1 year on animals kept under natural conditions. Testosterone levels and binding capacity of SBP show opposite seasonal evolution: in autumn, when testosterone levels are low, SBP binding capacity is maximum; during the resumption of testicular endocrine function, SBP binding capacity decreases; then, during the breeding season, SBP binding capacity is low and constant until July and, in August as testosterone levels decrease, SBP binding capacity increases. These preliminary results constitute a first demonstration of seasonal variations in SBP binding capacity in a hibernating mammal.     

Pancreatic A cell response to arginine in the hibernating hedgehog (Erinaceus europaeus)

Pancreatic A cell response to arginine was measured in hedgehogs during the periods of lethargy and arousal and then during activity. Spontaneous plasma glucagon concentrations were lower during lethargy than during activity, and they increased during arousal. Arginine administration induced a slight, but significant delayed increase in plasma glucagon concentration in the lethargic hedgehog (body temperature: 6 degrees). During arousal, in vitro glucagon secretion was temperature dependent suggesting that body rewarming might, in itself, be an important stimulating factor of the A cells. In the presence of arginine, the glucagon output of the pancreas of lethargic hedgehogs was high at low temperatures. It decreased to a nadir at 19 degrees and increased up to 37 degrees. However, the basal or arginine-stimulated glucagon secretion of animals in lethargy was higher than that of animals in activity. These characteristics suggested the presence of a particular pool of cold-adapted enzymes in the A cells of lethargic hedgehogs.     

Retracted: Effect of melatonin administration and long day‐length on endocrine cycles in the hedgehog Erinaceus europaeus

The above article [1], published online on 30 January 2007 (but previously in print in March 1990) in Wiley Online Library ( www.wileyonlinelibrary.com ), and in volume 8, pp. 193–204, has been retracted by agreement between the authors, the journal Editor in Chief, Russel Reiter, and John Wiley & Sons. This article is a duplicate of one published in the Journal of Pineal Research volume 8, issue 1. The article was duplicated due to an error at the publisher. Reference 1. Fowler PA, Racey PA. Effect of melatonin administration and long day‐length on endocrine cycles in the hedgehog Erinaceus europaeus. J Pineal Res 1990; 8 :193–204.     

Factors controlling the annual ovarian cycle in the toad Bufo bufo bufo (L.)

Sixty adult-sized female toads (weighing 60–100 g) were brought into the laboratory (21°C) late in the active season (about 1 September) and fed at a moderate level (once a week) and a high level (thrice a week). Hemiovariectomy 1 month later showed that 23 toads were sexually mature, the ovaries containing populations of oocytes in late second growth phase (SGP). Of the remaining toads, 2 were infantile, 22 were juvenile, and 13 were nonmature adults, the ovaries lacking populations of oocytes in late SGP. Ovaries lacking populations of late SGP oocytes but containing fully developed populations of first growth phase (FGP) oocytes had only occasionally recruited oocytes to the SGP in the group of toads fed once a week, and in about half the animals in the group of toads fed thrice a week. Gonadotropin (HCG) treatment of the hemiovariectomized, and hypophysectomized, toads caused normal recruitment and second growth in populations of oocytes in the ovaries lacking SGP oocytes, but not in ovaries already possessing normal populations of SGP oocytes. It is thus indicated that the common lack of normal populations of SGP oocytes in “adult-sized” female toads late in the active season is due to low rates of gonadotropin secretion and not to low sensitivity of the ovary toward gonadotropin. The HCG-stimulated growth of oocytes was approximately linear throughout the SGP from oocyte diameters of 0.4–0.8 mm up to sizes approaching the final, about 1.5 mm.     

Ultrastructure of folliculo-stellar cells in the hypophyseal pars distalis of the rock squirrel (Citellus variegatus Erxleben), the dormouse (Graphiurus murinus Desmaret), and the hedgehog (Erinaceus europaeus Linnaeus)

In the hypophysis of the Rock squirrel (Citellus variegatus Erxleben), the African dormouse (Graphiurus murinus Desmaret), and the Hedgehog (Erinaceus europaeus Linnaeus), besides the granulated cells, the pars distalis includes a cell type which can be identified only by electron microscopy and which corresponds to a similar category described under various names in several species of vertebrates. According to their general aspect and to the relations between these cells, we call them folliculostellar cells (FSC). These cells have the same aspect both in males and females. They limit microvesicles in the lumen of which there is more or less electron dense amorphous substance, and in the African dormouse only there are crystalline-looking inclusions. The cells surrounding the cavity, interlocked by junctional complexes, send many microvilli to the follicular cavity. They have long thin strectched processes between granulated cells up to the basal parenchymatous and capillary membranes. These FSC either contain rare granulations elaborated in the Golgi apparatus or none. However, various organelles, more or less developed, are present. In the African dormouse, there are junctional complexes not only between FSC but also between this type and various granulated cells. In the hedgehog, close relations between mitochondria and junctional complexes are frequently noticed. These results are compared with the observations on cells of this type described by different authors.     

The annual testicular cycle in the turtle, Chrysemys picta: a histochemical and electron microscopic study

This work is a study of testicular function in Chrysemys picta using changes in ultrastructure and steroid histochemistry as indices of Leydig and Sertoli cell activity. The cytological features of these cells are described in reference to four periods of tubular development. Leydig and Sertoli cells show distinct changes in morphological appearance during the seasonal cycle. Leydig cells are hypertrophic with an active 3 beta-hydroxysteroid dehydrogenase (HSD) and abundant smooth endoplasmic reticulum (SER) in early spring when androgen levels are high and animals mate and atropic in mid-summer when spermatogenesis is proceeding. Leydig cell atrophy is associated with a reduction in the volume of cytoplasm and SER. Leydig cells become active again in the fall showing a return toward the spring condition, with an increase in 3 beta-HSD activity. In contrast, although Sertoli cells show variations in abundance of organelles and inclusions during the annual cycle, no obvious degenerative changes could be seen and SER is always present. 3 beta-HSD enzyme activity in Sertoli cells is weak or absent in spring but intense during summer. Taken together, these observations suggest that Sertoli and Leydig cell functions are asynchronous.     

Effect of pinealectomy on the annual testicular cycle of Calotes versicolor

Pinealectomy resulted in an earlier recrudescence and a later regression of the annual gonadal cycle of the lizard Calotes versicolor. Spermatozoa appeared early and were present throughout the course of the experiment, namely, for 11 months. In control lizards (sham-operated, intact), on the other hand, spermatozoa appeared in late April and were observed only until August, a period of 5 months. The sex segments of the kidneys showed a cycle similar to the cycle of the testes in both groups.     

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.     

Effect of Melatonin Administration and Long Day-Length on Endocrine Cycles in the Hedgehog Erinaceus europaeus

The effects of exogenous melatonin (subcutaneous implants containing 0.031 +/- 0.006 mg/gm body mass melatonin) or long photoperiod (18L:6D) on wild-caught adult male hedgehogs were studied. Hedgehogs were implanted with melatonin-filled or empty capsules in May, August, or September, or maintained under long photoperiod from August. Blood samples collected at monthly intervals were assayed for testosterone, melatonin, and thyroxin. Melatonin-filled capsules elevated plasma melatonin concentrations for 4-6 months. Although melatonin administration in May depressed plasma testosterone levels, testicular reactivation was advanced by 1 month the following year, and the characteristic prehibernal gain in body mass was abolished. Melatonin administration in August had no effect on plasma testosterone concentrations but reduced body mass fluctuations before and during hibernation. Hedgehogs receiving melatonin in September recovered early from hibernal body mass loss and showed a 2 month advance in testicular reactivation the following year. Maintaining hedgehogs at 18L:6D photoperiod, however, elevated plasma melatonin concentrations. Testicular reactivation the following spring was delayed by 1 month, ended 3 months early, and testosterone concentrations were depressed. All treatments depressed plasma thyroxin levels. These results suggest that elevated melatonin levels during winter are important in the regulation of endogenous endocrine cycles in the hedgehog. Hedgehogs do not respond positively to melatonin at the end of the breeding season, but are again responsive to melatonin as early as September.     

Effect of Melatonin Administration and Long Day-Length on Endocrine Cycles in the Hedgehog Erinaceus europaeus

The effects of exogenous melatonin (subcutaneous implants containing 0.031 +/- 0.006 mg/gm body mass melatonin) or long photoperiod (18L:6D) on wild-caught adult male hedgehogs were studied. Hedgehogs were implanted with melatonin-filled or empty capsules in May, August, or September, or maintained under long photoperiod from August. Blood samples collected at monthly intervals were assayed for testosterone, melatonin, and thyroxin. Melatonin-filled capsules elevated plasma melatonin concentrations for 4-6 months. Although melatonin administration in May depressed plasma testosterone levels, testicular reactivation was advanced by 1 month the following year, and the characteristic prehibernal gain in body mass was abolished. Melatonin administration in August had no effect on plasma testosterone concentrations but reduced body mass fluctuations before and during hibernation. Hedgehogs receiving melatonin in September recovered early from hibernal body mass loss and showed a 2 month advance in testicular reactivation the following year. Maintaining hedgehogs at 18L:6D photoperiod, however, elevated plasma melatonin concentrations. Testicular reactivation the following spring was delayed by 1 month, ended 3 months early, and testosterone concentrations were depressed. All treatments depressed plasma thyroxin levels. These results suggest that elevated melatonin levels during winter are important in the regulation of endogenous endocrine cycles in the hedgehog. Hedgehogs do not respond positively to melatonin at the end of the breeding season, but are again responsive to melatonin as early as September.     

An immunocytochemical and ultrastructural study of the endocrine pancreas of Sparus auratus L. (Teleostei)

The pancreatic endocrine cells of Sparus auratus (gilthead sea bream) are concentrated in two or three principal islets, or Brockmann bodies, and numerous smaller islets embedded in the exocrine tissue. Insulin-, glucagon-, somatostatin-, and pancreatic polypeptide (PP)-immunoreactive cells were identified in all pancreatic islets of S. auratus using an indirect immunocytochemical (PAP) method. Insulin-immunoreactive cells were found in the central region of the islets. Glucagon-immunoreactive cells could be seen at the periphery of the islets and isolated in the exocrine tissue surrounding the large principal islet. Somatostatin-immunoreactive cells were distributed throughout the islets. PP-immunoreactive cells were clustered, in a limited shallow section, being found in no other part of the large principal islet whereas, in the smaller islets, these cells were more numerous and found in the whole peripheral area. Four cell types were identified in the pancreatic islets of S. auratus by electron microscopy. A,B,D and PP cells were characterized by the shape, size, and electron density of their respective secretory granules.     

Plasma and testicular estradiol and plasma androgen profile in the male frog Rana esculenta during the annual cycle

Seasonal plasma and testicular estradiol levels were measured in the male frogs, Rana esculenta, by radioimmunoassay. In plasma samples a simultaneous measurement of androgens was carried out in order to investigate a possible relationship between androgens and estradiol-17 beta. Concomitantly with the estradiol-17 beta peak in plasma and testes during the April-May period, plasma androgens sharply decreased.     

Pancreatic endocrine cells in sea bass (Dicentrarchus labrax L.) II. Immunocytochemical study of insulin and somatostatin peptides.

Insulin (INS)- and somatostatin (SST)-immunoreactive cells were demonstrated by light immunocytochemistry in the endocrine pancreas of sea bass (Dicentrarchus labrax). INS-immunoreactive cells were identified using bovine/porcine, bonito, and salmon (s) INS antisera; the immunostaining was abolished when each antiserum was preabsorbed with its respective peptide but not with unrelated peptides. These cells also reacted with mammal (m) SST-28 (4-14) antiserum. The immunoreaction did not change when this antiserum was preabsorbed by bovine INS. INS-immunoreactive cells were located in the central part of the endocrine areas of the principal, intermediate, and small islets. Two SST-immunoreactive cell types (D1 and D2) were revealed. D1 cells, immunoreactive to SST 14 (562) and sSST-25 antisera, were located next to the glucagon-immunoreactive cells in the peripheral part of the endocrine areas. D2 cells, immunoreactive to SST-14 (562), SST-14 (566), and mSST-28 (4-14) antisera, were found in apposition to the INS-immunoreactive cells. The specificity controls showed that D1 cells expressed sSST-25-like peptides, while D2 cells might contain SST-14 and/or mSST-28-like peptides. The close topographic association between the different SST-immunoreactive cells and both glucagon- and insulin-immunoreactive cells might indicate the existence of a specific paracrine regulation of each endocrine cell type in the sea bass endocrine pancreas.     

Aromatase activity in the European sea bass (Dicentrarchus labrax L.) brain. Distribution and changes in relation to age,sex, and the annual reproductive cycle

Cytochrome P450 aromatase activity (AA) was measured in different tissues of the sea bass (Dicentrarchus labrax L.) using a tritiated water release assay that was previously optimized and validated for this species. In adult fish entering the reproductive season, AA was highest on a per mg protein basis, in the brain (2.04+/-0.4 pmol/mg prot/h; mean+/-SEM), followed by the ovary (0.59+/-0.1) and was detectable in visceral fat (0.21+/-0.05), liver (0.08+/-0.009), and head kidney (0.03+/-0.004). However, AA was negligible in the rest of the tissues tested: heart, testis, muscle, and spleen. Consistent with results obtained in other species, dissection of the brain into its major constitutive parts revealed that AA was concentrated in areas implicated in the control of reproduction, including the olfactory bulb, telencephalon, and hypothalamus (range: 2.6-16.2 pmol/mg prot/h), as well as the pituitary gland (6.2-9.3 pmol/mg prot/h). Lower AA was noted in the optic bulb, cerebellum, and medulla. However, in contrast to some previously published reports concerning the content and distribution of neural aromatase in fish, males consistently exhibited higher AA than females. In one-year-old juvenile fish completing the process of gonadal sex differentiation, brain AA (0.63 pmol/mg prot/h) was similar in both sexes and ten times lower than that measured in the brain of first time spawners (6.52 pmol/mg prot/h), in this case with males showing an overall higher (24%) activity than females. When surveyed throughout the year, brain AA dramatically changed during the reproductive cycle. Maximum average values of approximately 7 pmol/mg prot/h were obtained that coincided with the spawning season. The peak in brain AA was preceded by two and one months by the peak of plasma testosterone and the peak of the gonadosomatic index, respectively. This is the first measurement of the distribution of the activity of a steroidogenic enzyme in the sea bass, an established model in comparative endocrinology. Together, these results demonstrate sex- and seasonally-related variations in AA and establish the basis for further comparative studies of certain androgen-mediated actions through locally formed estrogen in both central and peripheral targets.     

The endocrine activities of 8-prenylnaringenin and related hop (Humulus lupulus L.) flavonoids

The female flowers of the hop plant have long been used as a preservative and a flavoring agent in beer, but they are now being included in some herbal preparations for women for "breast enhancement." This study investigated the relative estrogenic, androgenic and progestogenic activities of the known phytoestrogen, 8-prenylnaringenin, and structurally related hop flavonoids. 6-Prenylnaringenin, 6,8-diprenylnaringenin and 8-geranylnaringenin exhibited some estrogenicity, but their potency was less than 1% of that of 8-prenylnaringenin. 8-Prenylnaringenin alone competed strongly with 17ss-estradiol for binding to both the alpha- and ss-estrogen receptors. None of the compounds (xanthohumol, isoxanthohumol, 8-prenyl-naringenin, 6-prenylnaringenin, 3'-geranylchalconaringenin, 6-geranylnaringenin, 8-geranylnaringenin, 4'-O:-methyl-3'-prenylchalconaringenin and 6,8-diprenylnaringenin) nor polyphenolic hop extracts showed progestogenic or androgenic bioactivity. These results indicate that the endocrine properties of hops and hop products are due to the very high estrogenic activity of 8-prenylnaringenin and concern must be expressed about the unrestricted use of hops in herbal preparations for women.     

Seasonal reproductive endocrine profiles in two wild mammals: the red fox (Vulpes vulpes L.) and the European badger (Meles meles L.) considered as short-day mammals

The annual cycle of the testicular function (testis and epididymis weights and plasma testosterone levels) were considered in relation to seasonal variations in plasma LH and prolactin concentrations in two wild European mammals: the badger and the fox. Phase relationships were established between the annual prolactin cycles and daylight duration. The influence of castration on the seasonal variations in plasma LH levels was also studied. The resumption of activity in the testicular function occurs during autumn for both species. The reproduction period begins in winter but it is over by the beginning of spring for the fox whereas for the badger it lasts until early summer. In the same way, the annual cycle of the gonadotrophic function which, in the fox, presents only one maximum at the end of autumn, is bimodal in the badger with one maximum in January and a second in June. On the other hand, both species have a similar annual prolactin cycle, which shows an increase from the winter solstice onwards, in synchronization with the increase in daily light duration. The highest prolactin levels are measured in spring followed by a decrease during summer. This result calls into question the role played by prolactin in the regulation of the testicular function in as far as the two species have an annual reproductive cycle of the 'short-day' type (onset of activity occurring before the winter solstice) but show seasonal prolactin variations similar to those described for 'long-day' species.