bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intracellular dehydration in the rat made diabetic with streptozotocin: effects of infusion
Authors: Anwana A. B. , Garland H. O. 
Published: December 2008

ABSTRACT
Metabolic and isotopic dilution techniques were used to investigate fluid balance and fluid volumes in rats made diabetic with streptozotocin before and after infusion. Uninfused diabetic rats had significantly (P < 0·01) lower total body water than controls (57·7±2·2 vs 65·7±1·4% (s.e.m.) fat free mass). This was due exclusively to a significantly (P < 0·001) reduced intracellular fluid volume (38·2±1·5 vs 45·4±1·4% fat free mass). Metabolic studies over the preceding 2 weeks showed that the fluid deficit in the diabetic group had resulted from a failure of the rats to increase their fluid intake to the same extent as their combined fluid losses. A 4-h saline infusion halved the fluid deficit in diabetic animals. The retained fluid was used to restore intracellular fluid volume which became comparable in diabetic and control rats (47·2±2·0 vs 46·4±1·0% fat free mass). The retention of infusate by diabetic animals to counteract their intracellular dehydration may partly explain the reduced urine output reported elsewhere in infused anaesthetized diabetic rats.
Journal of Endocrinology (1991) 128, 333–337
Variation in hypothalamic gonadotrophin-releasing hormone content, plasma and pituitary LH, and in-vitro testosterone release in a long-distance migratory bird, the garden warbler (Sylvia borin), under constant photoperiods
Authors: Bluhm C. K. , Schwabl H. , Schwabl I. , Perera A. , Follett B. K. , Goldsmith A. R. , Gwinner E. 
Published: December 2008

ABSTRACT
Changes in concentrations of hypothalamic gonadotrophin-releasing hormone (GnRH), pituitary and plasma LH, testicular mass, in-vitro release of testosterone, body mass and migratory activity were measured in male garden warblers (Sylvia borin) kept from November to June under a constant photoperiod of 12·8 h. Under such conditions garden warblers gradually change from the photorefractory to the photosensitive state and gonadal recrudescence then occurs.
Hypothalamic GnRH content was low from December to March, but increased in April to reach the highest levels in June. The spontaneous increase in GnRH was paralleled by increases in pituitary LH content, testicular mass and in-vitro testosterone release. Body mass decreased 1 month and nocturnal activity 2 months before the spontaneous increase in GnRH. Ovine LH increased in-vitro testosterone release over basal release at all times. The results suggest that in garden warblers (1) changes in hypothalamic GnRH content can occur under constant photoperiodic condition, (2) the gradual change from the photorefractory to the photosensitive state is not characterized by a gradual increase in hypothalamic content of GnRH (cf. starlings), and (3) Leydig cells are capable of testosterone release even during the photorefractory state.
Journal of Endocrinology (1991) 128, 339–345
Evidence for the control of testicular interstitial fluid volume in the rat by specific germ cell types
Authors: Sharpe R. M. , Bartlett J. M. S. , Allenby G. 
Published: December 2008

ABSTRACT
Following on from our recent evidence that Sertoli cells may regulate testicular interstitial fluid (IF) volume, this study has assessed whether depletion of specific germ cell types in vivo is associated with changes in recovered IF volume. Germ cell depletion was induced by either a single oral administration of 650 mg methoxyacetic acid (MAA)/kg or exposure of the testes to local heating (43 °C for 30 min). Treatment with MAA induced depletion or loss of most pachytene and later spermatocytes at 1–3 days and, because of maturation depletion, this resulted in the specific depletion of later germ cell types at 7–35 days. Testicular IF volume was unchanged at 1–7 days after MAA treatment but was increased significantly (P < 0·01) at 14 days and was nearly doubled (P< 0·001) at 21 days, before returning to control levels at 28–42 days. Serum LH (and FSH) levels were generally higher in MAA-treated rats, especially at 21 and 28 days, but there was no obvious correlation between LH levels and IF volume changes. Similarly, there was no relationship between IF volume changes and testicular weight or IF levels of testosterone. The increase in IF volume at 14–21 days after MAA treatment coincided with specific depletion of the later elongate spermatids (steps 14–19) and, when these cells reappeared in the testis, IF volume normalized.
This possible causal association was studied further in rats exposed to local testicular heating which, within 3 days, caused major depletion of pachytene spermatocytes and early (step 1–8) spermatids. However, testicular IF volume in heat-exposed rats did not change until 14 days, a time at which depletion of the later (step 9–19) spermatids first became evident; IF volume remained increased whilst these germ cells were absent or depleted. The pattern of change in IF volume in heat-exposed rats was not related to LH (or FSH) levels, which were raised at most time-points after heat treatment, nor to testicular weight which was decreased considerably at 3 days and declined progressively thereafter.
These data thus provide evidence that specific depletion of the most mature germ cell types (the elongate spermatids) is associated with specific changes in testicular IF volume, presumably via modulation of the secretion of vasoactive factors by the Sertoli cells. These findings also reinforce the growing evidence for the mutual interdependence of all of the cell types in the testis.
Journal of Endocrinology (1991) 128, 359–367
Insulin and growth hormone act synergistically to stimulate insulin-like growth factor-I production by cultured chicken hepatocytes
Authors: Houston B. , O'Neill I. E. 
Published: December 2008

ABSTRACT
Cultured chicken hepatocytes were used to investigate whether insulin and GH interact to regulate insulin-like growth factor-I (IGF-I) production in vitro. In the first set of experiments hepatocytes were preincubated for 6 h in hormone-free medium, and the effects of various combinations of insulin and GH on IGF-I production over the next 24 h were quantified by radioimmunoassay. Basal IGF-I production was 5·36 pg IGF-I/μg DNA and this was increased 1·31±0·13-fold (mean ± s.e.m.) by insulin, 1·90±0·24-fold by GH and 4·46±0·68-fold by a combination of insulin and GH. These results demonstrate that insulin and GH interact synergistically to stimulate IGF-I production in vitro. The synergism with GH occurred at physiological concentrations of insulin with half-maximal stimulation occurring at an insulin concentration of 6 ng/ml. In hepatocytes which had been exposed to insulin immediately before the start of the experiment, the presence of insulin was no longer required for maximal stimulation of IGF-I production by GH. This in-vitro system will facilitate the study of the molecular basis of the interaction between insulin and GH.
Journal of Endocrinology (1991) 128, 389–393
Quantitative analysis of the development of genital organs from the urogenital sinus of the fetal male mouse treated prenatally with a 5α-reductase inhibitor
Authors: Iguchi T. , Uesugi Y. , Takasugi N. , Petrow V. 
Published: December 2008

ABSTRACT
The role of 5α-dihydrotestosterone (DHT) in the development of the genital organs and in the differentiation of the genital tract into prostate, coagulating gland (CG), bulbo-urethral gland (BUG) and seminal vesicle (SV) in male mice exposed prenatally to the 5α-reductase inhibitor 6-methylene-4-pregnene-3,20-dione (6-MP) has been examined quantitatively. Female ICR mice were given 7 daily s.c. injections of the inhibitor (400 mg/day) starting on day 12 of gestation and the experiment was terminated on day 19 when the fetuses were removed by Caesarian section. In the prenatally 6-MP-exposed male mice the anogenital distance was significantly shorter than in the controls. Feminization of the nipples and hypospadias of the phallic urethra were noted. Development of prostate, CG and BUG was significantly suppressed. SV and testis development were not affected. These results lend further support to the conclusion that DHT is necessary for the development of the urogenital sinus (prostate, CG and BUG) and penis, and for the regression of the nipples in male mice. Reproductive abnormalities were not found in 90-day-old mice of both sexes exposed to 6-MP in utero. The 6-MP-exposed male and female mice had a normal reproductive capacity when mated with normal mice. These results show that 6-MP-induced growth retardation of reproductive organs is evident on day 19 of gestation, but that such retardation is no longer apparent in the adult.
Journal of Endocrinology (1991) 128, 395–401
Effects of luteolysis during late pregnancy on pituitary responsiveness to gonadotrophin-releasing hormone in the rat
Authors: Koiter T. R. , van der Schaaf-Verdonk G. C. J. , Schuiling G. A. 
Published: December 2008

ABSTRACT
We investigated whether the increase in the gonadotrophin response to gonadotrophin-releasing hormone (GnRH) during the last days of pregnancy and the occurrence of parturition on day 22 of pregnancy in rats are due to the increase in the plasma concentrations of oestradiol-17β after luteolysis, which occurs around day 20. In a first series of experiments we studied the effects of s.c. implantation of two capsules containing oestradiol on basal and GnRH-stimulated secretion of LH and FSH before and after luteolysis. Before luteolysis, ovariectomy increased basal LH and FSH; oestradiol treatment prevented this increase partly (FSH) or completely (LH). Ovariectomy also lowered the LH response to the infusion of GnRH (100 ng/h). Oestradiol treatment, on the other hand, increased the LH and FSH responses of both intact and ovariectomized rats above the level in intact non-treated control rats. After luteolysis, ovariectomy increased basal FSH only. Treatment with oestradiol did not prevent the increase in basal FSH and ovariectomy diminished the LH response to GnRH infusion. Oestradiol treatment maintained the LH response in ovariectomized rats at the control level and increased the FSH responses of both intact and ovariectomized rats to a higher level than in control rats. Furthermore, the LH and FSH responses of the oestradiol-treated groups of intact and ovariectomized rats were higher after luteolysis than before.
In a second series of experiments two capsules containing progesterone were s.c. implanted before or after luteolysis. Progesterone treatment suppressed the plasma concentration of oestradiol and the gonadotrophin responses to infusion of GnRH on the expected day of parturition in both groups of rats. Parturition was delayed only in the rats in which progesterone treatment had started before luteolysis. It was concluded that throughout pregnancy ovarian factors suppress basal FSH and that the increase in responsiveness to GnRH after luteolysis is due partly to an increase in oestradiol production and partly to an ovarian factor which augments the action of oestradiol. Furthermore, normal delivery does not require high plasma concentrations of oestradiol during the last day of pregnancy.
Journal of Endocrinology (1991) 128, 411–418
Influence of epidermal growth factor on liver regeneration after partial hepatectomy in mice
Authors: Noguchi S. , Ohba Y. , Oka T. 
Published: December 2008

ABSTRACT
The role of epidermal growth factor (EGF) in liver regeneration was studied in mice after partial hepatectomy. Two weeks before partial hepatectomy, mice were sham-operated (control) or sialoadenectomized (removal of submandibular glands) to reduce plasma EGF levels. Sialoadenectomized mice showed low plasma EGF levels (29·7 ±6·6 pmol/l; mean ± s.e.m.) compared with controls (66·0±8·3 pmol/l). After partial hepatectomy, sialoadenectomized mice were treated with or without a daily s.c. injection of 5 μg EGF and the rate of DNA synthesis in the regenerating liver was monitored by [125I]iododeoxyuridine uptake. Control mice showed a sharp peak of DNA synthesis at 48 h after partial hepatectomy while sialoadenectomized mice showed a delayed and broad peak at 84 h. Treatment of sialoadenectomized mice with EGF (5 μg/mouse per day) completely restored the pattern of DNA synthesis so that a sharp peak appeared at 48 h. The total liver DNA content of the control mice (79·1±2·5% of the preoperative level; mean ± s.e.m.) was significantly (P < 0·01) higher than that of the sialoadenectomized mice (65·2±3·0%) 3 days after partial hepatectomy, but this difference disappeared on day 7 when liver regeneration was almost completed in both groups. Treatment of sialoadenectomized mice with EGF increased total liver DNA content (78·2±2·9%) to that of control mice on day 3 after partial hepatectomy. In addition, normal mice showed a rapid increase in plasma EGF levels at 1–8 h after partial hepatectomy, whereas sialoadenectomized mice showed low plasma EGF levels throughout the course of the experiment. These results suggest that EGF derived from the submandibular glands plays a role in promoting the early stage of liver regeneration.
Journal of Endocrinology (1991) 128, 425–431
Increased concentrations of immunoreactive inhibin during conception cycles in the marmoset monkey: suppression with an LHRH antagonist and cloprostenol
Authors: Webley G. E. , Knight P. G. , Given A. , Hodges J. K. 
Published: December 2008

ABSTRACT
Peripheral concentrations of immunoreactive (ir) inhibin have been measured during the ovarian cycle and early pregnancy in the marmoset monkey. Blood samples were taken (three per week) during conception (n = 6) and non-conception (n = 5) cycles. Ir-inhibin was measured by radioimmunoassay using an antiserum raised against a synthetic peptide fragment of the α subunit of human inhibin. Monomeric bovine α subunit and 32 kDa bovine inhibin were used as tracer and standard respectively. In all animals low concentrations of ir-inhibin were recorded during the follicular phase (40–60 μg/l) of the cycle. After ovulation, ir-inhibin concentrations increased but the peak concentrations attained differed between conception and non-conception cycles. In non-pregnant animals ir-inhibin concentrations reached a maximum of 242±16 μg/l on days 12/13 after ovulation. In pregnant animals ir-inhibin concentrations were significantly (P < 0·05) higher (1·8-fold) than in non-pregnant animals on days 8/9 after ovulation, and reached a maximum value of 636±141 μg/l on days 20/21 after ovulation. Administration of an LHRH antagonist during the luteal phase on days 6–8 after ovulation resulted in a significant (P < 0·05) decrease in progesterone and ir-inhibin concentrations within 4 and 8 h respectively. This was prevented by co-administration with human chorionic gonadotrophin. Administration of cloprostenol to pregnant animals between days 17 and 20 after ovulation halved the initial concentrations of both inhibin and progesterone within 1·5 h. The increase in plasma ir-inhibin concentrations in the luteal phase and the apparent similarity in control of ir-inhibin and progesterone supports a luteal source of ir-inhibin in both conception and non-conception cycles. The higher levels of ir-inhibin from days 8/9 after ovulation in conception cycles were not related to any detectable increase in peripheral concentrations of chorionic gonadotrophin and occurred at least 4 days before the expected time of implantation. This suggests a role for the conceptus in inhibin secretion which may involve the release of an embryo message before implantation.
Journal of Endocrinology (1991) 128, 465–473
BREAST CARCINOMAS SYNTHESIZE FACTORS WHICH INFLUENCE OSTEOBLAST-LIKE CELLS INDEPENDENTLY OF OSTEOCLASTS IN VITRO
Authors: Evans C E , Ward C , Braidman I P 
Published: December 2008

ABSTRACT
Bone metastases in breast cancer may be osteolytic, osteosclerotic, or a mixture of the two. Although stimulation of bone resorption by breast cancer cells has attracted some interest, the formation of osteosclerotic secondary tumours and the influence of human mammary carcinoma cells on osteoblasts (bone forming cells), both important in understanding breast cancer - bone interactions, have been largely neglected. We therefore examined the effects of conditioned medium (CM) from two cultured human breast cancer cell lines (MCF7 and ZR-75) and from primary cultures of breast carcinomas from two patients, on osteoblasts and recruitment of bone-resorbing cells (osteoclasts) in vitro. Osteoblast-like cells (BDC) were cultured from human trabecular bone explants. Osteoclast maturation was studied in fetal rat calvaria cultured on collagen gels. CM from the MCF-7 line and cells derived from one patient each inhibited BDC DNA synthesis, but stimulated osteoclast recruitment. In contrast, CM from the second patient's cells or ZR-75 enhanced DNA synthesis in BDC, but blocked osteoclast maturation. This suggests that human breast carcinomas secrete soluble factors which influence both osteoclasts and osteoblasts. A further unexpected implication is that mammary carcinoma cells may cause local osteosclerosis by directly stimulating osteoblasts, rather than through raised bone turnover in metastases.
EVIDENCE FOR THE SECRETION OF INHIBIN-LIKE IMMUNOREACTIVITY FROM CULTURED HUMAN ADRENAL CELLS
Authors: Haji M. , Nishi Y. , Tanaka S. , Ohashi M. , Sekiya K. , Hasegawa Y. , Igarashi M. , Sasamoto S. , Nawata H. 
Published: December 2008

ABSTRACT
We have studied the production and release of inhibin-like immunoreactivity in the human adrenal gland. Extract of human adrenal glands showed a displacement curve paralled with the inhibin standard. Inhibin-like immunoreactivity contents in the adrenal gland was 1893±474 (mean±S.D.) IU/g wet weight tissue. ACTH stimulated the secretion of inhibin-like immunoreactivity as well as cortisol and aldosterone in a dose-dependent manner in the cultured adrenal cells. These results indicate that the human adrenal gland produces and secretes inhibin-like peptide in response to ACTH.
Desensitization studies using perifused rat pituitary cells show that growth hormone-releasing hormone and His-d-Trp-Ala-Trp-d-Phe-Lys-NH2 stimulate growth hormone release through distinct receptor sites
Authors: Blake A. D. , Smith R. G. 
Published: December 2008

ABSTRACT
The hexapeptide His-d-Trp-Ala-Trp-d-Phe-Lys-NH2 (GHRP-6) and GH-releasing factor (GHRH) produced a rapid release of GH upon perifusion of dispersed rat pituitary cells. In contrast to the native hormone GHRH, GHRP-6 elicited a response of short duration. When perifusion of each secretagogue was continued until the cells no longer released GH, a challenge by the alternative secretagogue immediately resulted in a secondary release of GH. These results are consistent with each secretagogue causing desensitization of discrete receptor-linked second messenger pathways. Cells which were perifused for 1 min with GHRP-6 required continued perifusion with culture medium alone for 60 min before they completely regained responsiveness to a subsequent challenge with GHRP-6. Somatostatin (SRIF) was able to inhibit the action of either secretagogue completely. However, when both GHRH and GHRP-6 were perifused together, SRIF attenuated but did not block GH secretion. These perifusion data add support to conclusions derived from static cell culture studies, that GHRH and GHRP-6 act through different receptor sites and that through discrete signalling pathways their individual effects on GH release are amplified
Journal of Endocrinology (1991) 129, 11–19
Autonomous FSH synthesis in vitro in anterior pituitary glands and grafts from female rats
Authors: van Dieten J. A. M. J. , de Koning J. , van Rees G. P. 
Published: December 2008

ABSTRACT
When pituitary glands from intact female, but not from ovariectomized rats, are incubated for 8 h in medium TC199 without further additives, FSH is synthesized. This LHRH-independent (or autonomous) FSH synthesis is prevented when bovine follicular fluid (bFF) is added to the incubation medium.
Results from preliminary experiments, however, indicate no clear autonomous FSH synthesis after long-term absence of LHRH. To investigate the regulatory mechanisms involved in autonomous FSH synthesis and release, pituitary glands (exposed to endogenous LHRH) and pituitary grafts (not exposed to endogenous LHRH) from intact and ovariectomized rats were incubated for 8 h in medium TC199. Total FSH content (FSH released plus FSH remaining in the tissue) was compared with that in non-incubated glands or grafts, giving an indication of FSH synthesis. In addition, some of the animals were given LHRH pulses for 40 h before incubation. When pituitary tissue was taken from intact female rats, FSH synthesis occurred in the animals' own glands and in grafts from LHRH-pretreated rats. No FSH synthesis was seen in ovariectomized rats with or without pretreatment with bFF and/or LHRH. However, when ovariectomized rats had been pretreated with oestrogen, FSH synthesis was measured in vitro after pulsatile LHRH treatment in vivo.
The results indicate that autonomous FSH synthesis in vitro is dependent upon previous (in vivo) exposure of the glands to both oestrogen and LHRH.
Journal of Endocrinology (1991) 129, 27–33
Immunocytochemical localization of inhibin α-subunit in the human corpus luteum
Authors: Smith K. B. , Millar M. R. , McNeilly A. S. , Illingworth P. J. , Fraser H. M. , Baird D. T. 
Published: December 2008

ABSTRACT
The localization of inhibin α-subunit within the human corpus luteum was investigated. The antiserum used was raised in sheep against the first 1–23 amino acid sequence of the N-terminus of the human inhibin α-subunit. Using the avidin-biotin immunoperoxidase technique, intense immunostaining was localized within the granulosa-lutein cells of the corpus luteum, with absence of staining in the theca-lutein cells and surrounding ovarian tissue. Similar distribution of inhibin α-subunit immunostaining was observed in 12 corpora lutea obtained during the early, mid- and late-luteal phases and no changes in intensity were apparent at these different stages. Negative controls were obtained by applying antiserum which had been preabsorbed overnight with excess inhibin peptide in place of primary antiserum and also normal non-immune sheep serum as a substitute for primary antiserum. These results provide further evidence that the human corpus luteum is a significant source of immunoreactive inhibin during the normal human menstrual cycle. The specific localization within the granulosalutein cells of the corpus luteum suggests that inhibin α-subunit production may originate from a discrete cell population within the human corpus luteum.
Journal of Endocrinology (1991) 129, 155–160