bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFECTS OF PHYTO-OESTROGENS ON PROGESTERONE SYNTHESIS BY ISOLATED BOVINE GRANULOSA CELLS
Authors: KAPLANSKI ORA , SHEMESH MORDECHAI , BERMAN A.
Published: December 2008

The effects of phyto-oestrogens on progesterone synthesis by isolated bovine granulosa cells in vitro were assessed. Various concentrations (0·037–3700 nmol/l) of biochanin A, genistein or oestradiol were added to cultures of bovine granulosa cells and the consequent changes in progesterone synthesis were measured. The effects of alkali-soluble extracts of Rhodes grass (Chloris gayana) and fodder beet (Beta vulgaris, var.) were also examined. Another series of experiments tested the effects of genistein and oestradiol on the increase of progesterone synthesis brought about by the addition of LH to the culture medium. It was found that biochanin A and genistein increased progesterone synthesis by 40–50% when added in concentrations of 3·5 and 185 nmol/l respectively. At higher concentrations progesterone synthesis declined and was significantly (P < 0·05) inhibited at concentrations of phyto-oestrogens greater than 176 nmol/l for biochanin A and 1850 nmol/l for genistein. Oestradiol showed similar effects: maximum stimulation of progesterone secretion occurred in the presence of 0·184 nmol/l; inhibition was found with concentrations of greater than 1·84 nmol/l. Extracts of Rhodes grass but not of fodder beet also showed biphasic effects. Both genistein and oestradiol in high concentrations (3700 and 3671 nmol/l respectively) inhibited the increase in progesterone synthesis provoked by LH. The data indicated that phyto-oestrogens, like oestradiol, have a dose-related, biphasic effect on steroidogenesis in the isolated bovine granulosa cell system.
ESTIMATION OF THYROIDAL RADIOIODIDE CLEARANCE IN THE DOMESTIC FOWL (GALLUS DOMESTICUS)
Authors: DAVISON T. F. , ROWELL J. G. , REA J.
Published: December 2008

A method for estimating thyroidal clearance of radioiodide from the blood plasma of the domestic fowl is described. It differed from published methods in a number of ways. (1) It utilized total thyroidal radioiodide concentration (IT) and did not require the use of goitrogens or the separation of free and protein-bound components. (2) Radioiodide was injected intravenously rather than by other routes. (3) Plasma radioiodide concentration (IB) was determined from several serial samples from each bird rather than once only. (4) The method allowed the clearance constant (α; μl/min per mg) to be estimated for individual birds, rather than from groups, thereby enabling effective replication for comparative experiments. The constant was estimated from the model dIT/dt = αIB, measurements being made within 120 min after injection to ensure that exit of radioiodide from the thyroid was negligible. The improved method resulted in estimates of clearance constants which agreed well with published findings.
STUDIES ON THE CORTICOTROPHIN RELEASING ACTIVITY OF A POSTERIOR PITUITARY EXTRACT
Authors: KIRKLAND S. C. , ELLISON M. L.
Published: December 2008

The posterior pituitary gland is considered to be a source of a corticotrophin releasing factor(s) distinct from vasopressin. In this study, the corticotrophin releasing activity of a commercial posterior pituitary extract (Pitressin) and synthetic vasopressin were compared, using a perfused rat pituitary monolayer system. Pitressin was shown to have approximately twice the releasing activity than could be accounted for by its vasopressin content. Fractionation of the posterior pituitary extract, using high pressure liquid chromatography, showed it to contain active material co-eluting with synthetic vasopressin, and at least three other corticotrophin releasing factors. The releasing activity of the most active of these factors was investigated and was found to stimulate ACTH release in a dose-related manner.
STEROIDALINTERACTIONS IN THE REGULATION OF MATERNAL BEHAVIOUR IN VIRGIN FEMALE RATS: EFFECTS OF TESTOSTERONE, DIHYDROTESTOSTERONE, OESTRADIOL, PROGESTERONE AND THE AROMATASE INHIBITOR, 1,4,6-ANDROSTATRIENE-3,17-DIONE
Authors: BRIDGES R. S. , RUSSELL D. W.
Published: December 2008

The effects of exposure to concentrations of androgens, oestradiol (OE2) and progesterone similar to those found during pregnancy on the induction of maternal behaviour were investigated in female rats. In the first experiment the effects of testosterone and dihydrotestosterone (DHT) administered in combination with progesterone (using silicone elastomer capsules) on the induction of behavioural responsiveness towards young (crouching, retrieval and grouping of pups) were measured in ovariectomized virgin rats. Hormonally treated animals were exposed to testosterone or DHT from day 1 of treatment to the end of behavioural testing, while progesterone was administered for 10 days (days 3–13). Testing for maternal responsiveness began on day 14 and lasted until day 23. Significant reductions in latencies to show individual aspects of and complete maternal behaviour were found only in animals treated with a combination of testosterone and progesterone (range of mean latencies for showing one aspect of, to complete, maternal behaviour = 1·0–1·4 days). The mean latencies of the other hormonally treated animals ranged from 5 to 6 days and were similar to those of non-hormonally treated control rats.

The second experiment examined the possibility that stimulation of maternal behaviour in animals given testosterone and progesterone resulted from the aromatization of testosterone to OE2. Ovariectomized virgin rats were implanted with capsules containing testosterone and others with the aromatase inhibitor, 1,4,6-androstatriene-3,17-dione (ATD) on day 1, and with progesterone capsules on day 3. Progesterone capsules were removed on day 13 and behavioural testing commenced on day 14. Treatment with testosterone and progesterone failed to stimulate maternal behaviour in rats treated with ATD.

In a third study ovariectomized virgin rats were implanted with OE2 on day 1 and progesterone on day 3. The progesterone implants were removed on day 13 and testing began on day 14. Significant reductions in latencies to show all aspects of maternal behaviour were found in these rats.

In a final study progesterone capsules remained in OE2- and progesterone-treated rats from day 3 until the completion of behavioural testing. The presence of progesterone implants throughout the test period (days 14–23) blocked the rapid onset of maternal responsiveness induced by removal of progesterone on day 13 shown in rats treated with OE2 plus progesterone in experiment 3. These data suggest that during gestation testosterone, through its conversion to OE2, synergizes with progesterone to help stimulate the development of the capacity of the female animal to respond maternally to young, a capacity unmasked by withdrawal of progesterone before parturition.
BEHAVIOURAL ACTION OF ANDROGEN IN THE DOVE: EFFECTS OF LONG-TERM CASTRATION ON RESPONSE SPECIFICITY AND BRAIN AROMATIZATION
Authors: HUTCHISON J. B. , STEIMER TH. , DUNCAN R.
Published: December 2008

Differences in the effectiveness of oestradiol-17β and testosterone on male courtship and vocal behaviour were examined in long-term castrated doves. Nest-orientated behaviour was restored by intramuscular injection of oestradiol-17β. Testosterone was effective in restoring aggressive courtship and vocal behaviour, but not for the nest-orientated behaviour. The effects of these hormones were separable, therefore, under conditions of prolonged androgen deficit, suggesting differences in their specificity of action. In-vitro assay of brain enzyme activity indicated that aromatization of testosterone to oestradiol-17β occurred in the preoptic area of long-term castrated doves. Preoptic aromatase activity of long- and short-term castrated doves did not differ. The ineffectiveness of testosterone in restoring nest-orientated behaviour in long-term castrated doves did not appear, therefore, to be due to a difference between the groups in the basal rate of testosterone aromatization in the preoptic area.
DYNAMICS OF THE FORMATION AND RELEASE OF CORTICOTROPHIN RELEASING ACTIVITY BY THE RAT HYPOTHALAMUS IN VITRO
Authors: GILLHAM B. , BECKFORD URSZULA , INSALL R. L. , SKELLY A. MCL. , JONES M. T.
Published: December 2008

The ability of the isolated rat hypothalamus, incubated in vitro, to form and secrete corticotrophin releasing factor (CRF) has been assessed. It was found that serotonin (10 ng/ml), when added to the hypothalamus in vitro, caused the release of CRF and an increase in the activity of CRF contained in the tissue. The activity of CRF was estimated by its ability to cause the secretion of ACTH (determined by the cytochemical assay procedure) from anterior pituitary fragments in vitro. Provided a minimum of 10 min 'rest' in serotonin-free medium was allowed between each challenge with the neurotransmitter, the response of the hypothalamus in vitro was maintained for at least 3 h. A detailed examination of the time-course of CRF formation and secretion following a single addition of serotonin showed that the release was well underway within 40 s and continued up to 4 min, but then ceased. On the other hand, the tissue content of CRF was found to be reduced significantly at 20 and 40 s, had returned to basal values at 1 min and continued to increase to reach a maximum at 4 min that was maintained at 6 min. The stimulated release was approximately six times greater than basal and the increase in content approximately ten times basal. Removal of the serotonin-containing medium after 6 min of stimulation was accompanied by a precipitous fall in the CRF contained in the tissue and this was significant 2 min later with CRF content back to basal levels within 4 min. The serotonin-induced increase in CRF content was shown to be greatest in the area of the ventral portion of the medial basal hypothalamus containing the median eminence and its attendant pituitary stalk.

The energy metabolite status of the hypothalamus in vitro under the conditions employed to cause the secretion of CRF was assessed. The rates of oxygen consumption and release of lactate, and the tissue concentrations of K+ and ATP were all determined and found to be comparable to values published for more conventional cerebral slice preparations for up to 2 h in vitro. At 3 h a fall in tissue K+ and an increase in the amount of lactate released into the medium suggested that the preparation was showing signs of becoming compromised metabolically and this trend was more obvious at 4 h when the ATP level had also fallen significantly.

In more limited cognate experiments the changes in ACTH formation and release induced in anterior pituitary fragments in vitro by the addition of hypothalamic extracts were studied. Once again the release of the hormone was accompanied by an increase in the ACTH content of the tissue. The increase in content reached a maximum by 10 min and then declined to basal levels within 10 min of removal of the CRF-containing medium. Thus, it is possible that degrading enzymes play an important role in the control of hormonal output from both tissues.
SUCKLING IN THE GUINEA-PIG: THE EFFECTS OF PASSIVE IMMUNIZATION WITH AN ANTISERUM TO OXYTOCIN
Authors: ROBINSON I. C. A. F. , PARSONS J. A.
Published: December 2008

Lactating guinea-pigs were passively immunized with an antiserum to oxytocin of high titre, specificity and avidity. Single i.v. injections of 0·1–0·4 ml antiserum produced high titres which decayed slowly (half-life ≃7 days). Passively administered antiserum was effective in vivo; the clearance of exogenous oxytocin from plasma was greatly slowed in immunized animals. Passive immunization with 0·4 ml antiserum reduced milk transfer to the litter during suckling episodes of 10 min, and overall litter growth rates were significantly decreased. Non-immune serum was without effect. Plasma neurophysin levels showed the same large rises during suckling in immunized animals, indicating that neurohypophysial activation was unimpaired. Despite the presence of high titres of antiserum, some milk transfer still occurred at milk ejection. In-vitro experiments showed that more than 25% of oxytocin remained free 20 s after mixing with plasma taken from passively immunized animals. It is probable that the antiserum in the circulation was unable to bind all the oxytocin released from the posterior pituitary gland before it reached the mammary gland.
INTERACTION BETWEEN PROLACTIN AND ANDROGENS IN THE ACCESSORY SEX ORGANS OF MALE MICE
Authors: KEENAN E. J. , KLASE P. A. , THOMAS J. A.
Published: December 2008

Treatment of adult male mice with varying doses of prolactin increased the weights of the seminal vesicles and the anterior prostate gland. Only in the seminal vesicles were these increases in organ weights associated with increased levels of DNA. In castrated mice, prolactin alone failed to alter the weights of the accessory sex organs or DNA content. However, the simultaneous administration of prolactin and testosterone resulted in enhanced androgenic stimulation of seminal vesicle weights and their DNA content. Prostatic weights, but not DNA content, were augmented by treatment with prolactin and testosterone. Although the kidneys exhibited androgen sensitivity, prolactin failed to enhance the effect of testosterone upon the kidney. Augmentation of androgen action in the accessory sex organs was observed only after treatment with prolactin or growth hormone. Prolactin also enhanced the effects of dihydrotestosterone and 5α-androstane-3α, 17β-diol, but not of 5α-androstane-3β,17β-diol.

These studies revealed that prolactin enhances the proliferative actions of androgens in mouse seminal vesicles, but not in the anterior prostate glands or the kidneys.
PATTERNS OF PLASMA PROLACTIN IN POST-PARTUM SUCKLED COWS
Authors: WEBB R. , LAMMING G. E.
Published: December 2008

Blood samples taken on alternate days through indwelling jugular venous catheters from 12 suckled cows between days 14 and 48 post partum contained significantly less prolactin than samples collected on intermediate days by jugular venepuncture. Samples taken through the catheter every 2 h for 72 h periods revealed a repetitive daily biphasic pattern of prolactin secretion with low concentrations at 09.00 and 19.00 h and high concentrations at 13.00 and 23.00 h.

In two groups of cows, one group calving at the beginning of March (increasing photoperiod) and the other calving during June (decreasing photoperiod), there was a significant negative correlation between stage of lactation and plasma prolactin concentrations in samples taken by venepuncture.
EFFECTS OF DENSE HOUSING ON THE GROWTH OF REPRODUCTIVE ORGANS, PLASMA TESTOSTERONE LEVELS AND FERTILITY OF MALE MICE
Authors: JEAN-FAUCHER CH. , BERGER M. , DE TURCKHEIM M. , VEYSSIERE G. , JEAN CL.
Published: December 2008

Male mice were raised in populations of two different sizes from birth to adulthood: six animals (three of each sex) or 30 animals (15 of each sex) being maintained in cages of the same dimensions. Animals were killed every 10 days from weaning to 60 days and at 90 days. Increased population size induced decreased body and seminal vesicle weights; testicular, pituitary and adrenal weights were little affected. Plasma testosterone levels were lowered by increasing population size over the period from weaning to 50 days but they were increased at 60 and 90 days. The age at which first fertile matings occurred was not affected. These results indicate that the endocrine function of the testis, as determined by the measures used here, was specifically affected by this differential housing.
STIMULATION OF RELEASE OF LUTEINIZING HORMONE FROM CULTURED PITUITARY CELLS BY 2- AND 4-HYDROXYLATED OESTROGENS
Authors: FRANKS S. , MERRIAM G. R. , GOODYER CYNTHIA G. , NAFTOLIN F.
Published: December 2008

We have examined the effects of the catechol oestrogens 2-hydroxyoestradiol (2-OHE2), 4-hydroxyoestradiol (4-OHE2) and 2-hydroxyoestrone (2-OHE1) and their corresponding primary oestrogens on secretion of LH and FSH by enzymatically dispersed rat anterior pituitary cells in monolayer culture.

Basal LH levels in the medium were significantly higher than in control wells when cells were exposed to 10−8m-oestradiol-17β for 40 h: oestrone and all three catechol oestrogens (in the same doses) also stimulated basal LH concentrations to levels quantitatively similar to those seen after oestradiol treatment. The same effects were observed when steroids were given at 10−9 mol/l. Oestradiol, 2-OHE2, and 4-OHE2 but not 2-OHE1 increased pituitary responsiveness to LH releasing hormone (LH-RH) (given in a range of doses from 10−11 to 10−6 mol/l). The responses of cells treated with 2-OHE2 and 4-OHE2 were similar, though less than the response seen after treatment with oestradiol. This contrasts with the very different oestrogenic effects of 2- and 4-OHE2 previously observed in vivo. Neither oestradiol nor the catechol oestrogens had any effect on basal or LH-RH-stimulated FSH release.
CONCENTRATIONS OF PROLACTIN AND LUTEINIZING HORMONE IN PLASMA OF DOVES IN RELATION TO INCUBATION AND DEVELOPMENT OF THE CROP GLAND
Authors: GOLDSMITH A. R. , EDWARDS C. , KOPRUCU M. , SILVER R.
Published: December 2008

The concentrations of prolactin and LH were measured in the plasma of male and female ring doves (Streptopelia risoria) during the breeding cycle. Prolactin concentrations were low during courtship and early incubation but increased markedly (P<0·01 in both sexes) between days 7 and 15 of incubation, during the period of rapid growth of the crop sac. Levels remained raised for 4 days after the young had hatched but then declined as the crop sacs gradually regressed. These observations showed that concentrations of prolactin were high at the time when the crop sacs were proliferating and producing 'milk' for feeding the young, but that there was no increase in prolactin secretion at the onset of incubation as occurs in ducks, hens and other birds. In samples taken from doves at various times of the day and night there was no increase in plasma prolactin during the first few days of incubation. Concentrations of LH in plasma were generally higher in male doves than in females, but in both sexes were significantly higher during courtship than during incubation and brooding the young. Concentrations increased again when the young were independent and the parents began a second round of courtship.
EFFECTS OF SHORT-TERM BILATERAL AND UNILATERAL CASTRATION AND ANDROGEN REPLACEMENT ON THE METABOLISM OF [3H]TESTOSTERONE IN VITRO BY THE EPIDIDYMIS OF THE IMMATURE RAT
Authors: FOLDESY R. G. , LEATHEM J. H.
Published: December 2008

The in-vitro metabolism of [3H]testosterone by the epididymis of the pubertal rat (55 days of age) has been examined after short-term bilateral and unilateral castration and androgen replacement. Bilateral castration did not decrease the metabolism of [3H]testosterone, but did result in a decline in the proportion of 5α-dihydrotestosterone produced and an increase in that of 5α-androstane-3α,17β-diol, androsterone and 5α-androstane-3,17-dione. Changes in metabolism occurred in the caput within 2 days after surgery, but not until 5 days after surgery in the cauda epididymidis. Daily testosterone treatment, which maintained prostatic growth in bilaterally castrated animals, did not restore normal androgen metabolism and increased further the production of androsterone and 5α-androstanedione by the cauda. In unilaterally castrated animals, androgen metabolism in epididymal tissue from the operated side was normal in the cauda but was indistinguishable in the caput from that of bilaterally castrated rats. These results indicate that (a) androgen metabolism by the caput, compared to that by the cauda, responds more quickly to androgen withdrawal and (b) that in the short term, normal androgen metabolism by the caput, but not the cauda, is dependent upon the presence of the ipsilateral testis. Furthermore, testosterone alone proved an inadequate replacement for bilateral castration which implies that the pubertal rat testis secretes additional compounds which are essential for normal function of the epididymis.
IN-VITRO UPTAKE AND METABOLISM OF [3H]CORTICOSTERONE BY MAMMARY GLANDS FROM PREGNANT, LACTATING AND POST-LACTATIONAL RATS AND BY PARAMETRIAL ADIPOSE TISSUE FROM LACTATING RATS
Authors: PEARLMAN W. H. , PENG L.-H. , PEARLMAN M. R. J.
Published: December 2008

The study was designed to determine the influence of the physiological state on the invitro uptake and metabolism of glucocorticoid hormone by the mammary gland. [3H]Corticosterone was accordingly incubated with minced mammary glands from pregnant, lactating and post-lactational rats. The total uptake of [3H]corticosteroid was obtained from the concentration of radioactivity by the tissue and the specific activity of the steroid substrate. The extent of 21-acylation was determined as the percentage of the radioactivity in the chromatographed tissue extracts attributable to 21-acyl-[3H]corticosterone. The results indicated that the uptake of [3H]corticosteroid increased with advancing pregnancy, attained a high plateau level during lactation, and steadily declined during the post-lactational period. The extent of 21-acylation of [3H]corticosterone varied from 10 to 40%, fluctuating widely in all physiological states, particularly during the post-lactational period. It was inferred that the stromal elements, presumably the adipocytes, of the mammary gland can also acylate the corticosteroid hormone, a view which gained experimental support from similar studies with minced parametrial adipose tissue from lactating rats.
THE POSSIBLE ROLE OF PROLACTIN IN THE REGULATION OF NESTING BEHAVIOUR AND THE SECRETION OF LUTEINIZING HORMONE IN BROODY BANTAMS
Authors: LEA R. W. , DODS A. S. M. , SHARP P. J. , CHADWICK A.
Published: December 2008

The time spent each day on the nest and the rate of formation of the brood patch before the onset of incubation were measured in bantams (Gallus domesticus) and related to changes in the concentrations of plasma LH and prolactin. The hens spent progressively more time on the nest in the 5 days before the onset of incubation so that by the first day of incubation they were spending more than 90% of their time in this way. The concentration of plasma prolactin increased while that of LH fell on successive days before the onset of incubation: the increase in plasma prolactin preceded the fall in plasma LH by 2 days. The formation of the brood patch closely followed the increase in the concentration of plasma prolactin. In four out of five bantams the increase in nesting behaviour was preceded by an increase in the secretion of prolactin. An injection of chicken prolactin antiserum into bantams incubating eggs resulted in a significant (P<0·05) increase in the plasma concentration of LH.

These observations suggest that, in the bantam, the onset of incubation is initiated by an increase in the secretion of prolactin which also suppresses the secretion of LH.
ACCUMULATION OF LUTEINIZING HORMONE, OESTRADIOL AND ANDROSTENEDIONE BY SHEEP OVARIAN FOLLICLES IN VIVO
Authors: McNATTY K. P. , DOBSON CAROLYN , GIBB MARION , KIEBOOM LINDA , THURLEY D. C.
Published: December 2008

The temporal relationships between the levels of LH in peripheral plasma and in follicular fluid of ovarian follicles in anaesthetized sheep were investigated for a 10-h period after a single i.m. injection of LH releasing hormone (LH-RH; 100 μg). The ovarian secretion rates of oestradiol and androstenedione and the levels of these steroids accumulating in different sized follicles at varying time-intervals after the LH-RH injection were also compared.

The data show that the rates at which pituitary LH enters and leaves the intrafollicular fluid-filled spaces are substantially slower than those of peripheral blood. Two hours after LH-RH injection the levels of LH in plasma had increased from 1 to 200 ng/ml, whereas in the follicle the levels remained at approximately 2 ng/ml. Ten hours after the LH-RH injection, the levels of LH in plasma had returned to basal values (∼1·4 ng/ml) but in both small and large follicles the levels of LH (∼20 ng/ml) were comparable to those present in similar sized follicles 4 h earlier.

The data also indicate that more than 90% of the oestradiol produced by a large antral follicle (≥5 mm diameter) probably enters the bloodstream without first accumulating within the follicular antrum. Finally it is concluded that the clearance of the small amount of oestradiol which does accumulate in the follicular antrum is negligible compared with the clearance of this hormone from peripheral plasma.
SUBSTANTIAL AMOUNTS OF GONADOTROPHIN-LIKE MATERIALS IN SERA OF NORMAL SUBJECTS
Authors: PALA A. , MARINELLI G. , Di GREGORIO R. , SPAMPINATO G. , MORO M. , CARENZA L.
Published: December 2008

Ultrafiltration of human sera resulted in increased levels of human chorionic gonadotrophin (hCG), LH and FSH measured by radioimmunoassay. The effect was greatly enhanced by chromatography of serum through Sepharose–protein A (which specifically binds immunoglobulin G) followed by ultrafiltration of the unretarded fractions.

Serum from a normally menstruating woman was treated by ultrafiltration and the retained fraction from 200 μl serum further chromatographed on a Sephadex G-150 Superfine column. The amounts of LH and FSH measured in the eluate by radioimmunoassay were higher by three orders of magnitude than those found in the untreated serum. Comparable amounts of hCG were also found in the eluate by two specific radioimmunoassays, and a value of 45 i.u. hCG was recovered in the eluate by bioassay.

Serum from another normally menstruating woman was applied to DEAE-cellulose and eluted stepwise using an elution gradient. The ultrafiltrate of one eluted fraction led to separation of a low molecular weight material which was able to neutralize the biological activity of a large dose of hCG.

The data support the hypothesis that substantial amounts of gonadotrophins are normally present in serum but that binding to inhibitors(s) prevents their assay in untreated sera.
EFFECT OF CHEMICAL SYMPATHECTOMY AND GANGLION BLOCKADE ON ANGIOTENSIN-STIMULATED FLUID ABSORPTION IN THE RAT JEJUNUM
Authors: DOREY P. G. , MUNDAY K. A. , PARSONS B. J. , POAT JUDITH A. , UPSHER MARY E.
Published: December 2008

A study has been made of the effects of chemical sympathectomy and ganglion blockade on the responses of rat jejunum in vivo to intravenous doses of angiotensin and noradrenaline capable of stimulating fluid transport. Pretreatment with 6-hydroxydopamine (chemical sympathectomy) or pentolinium tartrate (ganglion blockade) abolished the stimulatory actions of angiotensin II but left the responses to noradrenaline unimpaired. Dopamine, like noradrenaline, stimulated fluid transport but this response required very high dopamine infusion rates, was refractory to the dopamine antagonist sulpiride and was inhibited by the α-blocker phentolamine.

The possible interaction between angiotensin and the intestinal sympathetics is discussed with reference to control of extracellular fluid volume.
EFFECTS OF BROMOCRIPTINE AND OCCLUSION OF NIPPLES ON PROLACTIN RECEPTOR AND LACTOSE SYNTHETASE ACTIVITY IN THE MAMMARY GLAND OF THE LACTATING RAT
Authors: HAYDEN T. J. , SMITH S. V.
Published: December 2008

The response of. prolactin receptor and lactose synthetase to suppression of plasma concentrations of prolactin was examined in normal and occluded (teat-sealed) mammary glands of Sprague–Dawley rats. Rats, with mammary glands unilaterally occluded, were given bromocriptine (2·5 mg/kg per 12 h) between days 5 and 8 post partum. Bromocriptine reduced plasma prolactin concentrations from 460·4±120·8 (mean ±s.e.m.) to 2·56 ± 0·89 ng/ml within 12 h whilst concentrations in control rats were 553·4± 110·25 ng/ml. Lactose synthetase activity declined rapidly, within 24 h, in occluded glands of both groups but was maintained for 24 h in normal glands of bromocriptine-treated rats and decreased thereafter. Prolactin receptors also declined significantly within 24 h in occluded glands. Desaturation of the prolactin receptor by bromocriptine treatment in vivo was compared with desaturation by exposure of membranes to MgCl2 in vitro. Both treatments enhanced prolactin binding but the increase after treatment with MgCl2 may have been partly artefactual since there was a selective loss of protein from the membranes. These results indicate that the prolactin receptor in rat mammary gland may be maintained after acute suppression of prolactin secretion.
EFFECT OF INJECTED HUMAN CHORIONIC GONADOTROPHIN ON CAPILLARY PERMEABILITY, EXTRACELLULAR FLUID VOLUME AND THE FLOW OF LYMPH AND BLOOD IN THE TESTES OF RATS
Authors: SETCHELL B. P. , SHARPE R. M.
Published: December 2008

The subcutaneous injection of human chorionic gonadotrophin (HCG) into adult male rats caused appreciable rises in capillary permeability and lymph flow in the testis, accompanied by smaller rises in the volume of extratubular, extracellular fluid. Most of these changes were already apparent 8 h after injection, but became progressively greater during the next 12 h. Testicular blood flow was unchanged at 12 h but increased slightly between 12 and 16 h after injection. The primary effect is probably the increase in capillary permeability. The timing of these changes suggests that HCG does not affect the capillaries directly, but it would seem that the changes are due to some substances secreted by the testis in response to the HCG. It is clear that these changes will have important influences both on the access to the testicular cells of peptide hormones in the blood and also on the passage into the venous blood of hormones secreted by the testis.
UTERINE OESTROGEN AND PROGESTERONE RECEPTORS IN THE OVARIECTOMIZED RAT
Authors: MANNI ANDREA , BAKER REBECCA , ARAFAH B. M. , PEARSON O. H.
Published: December 2008

The effect was studied of repeated injections of oestradiol-17β (5, 10, 25, 50 μg) given for various lengths of time (3, 5, 9 days) on total cell content of oestrogen receptors and cytosol progesterone receptors in the uteri of ovariectomized rats. An additional group of rats was injected daily with 50 μg oestradiol benzoate (OB) for 9 days in order to achieve a more sustained concentration of oestradiol in the blood. Injections were begun 24 h after ovariectomy and the rats were killed 24 h after the last injection. Daily administration of 5 μg oestradiol prevented the initial transient rise in oestrogen receptors which was observed in the uteri of untreated rats after ovariectomy. Repeated injections of 10 μg oestrogen produced an initial lowering in oestrogen receptors after 3 days of treatment which was followed by a prompt rise at 5 and 9 days when treatment was continued. A significant reduction in oestrogen receptors occurred at all times studied when rats were injected daily with 25 and 50 μg oestradiol. A more profound reduction in oestrogen receptors was observed in the group of rats treated for 9 days with 50 μg OB. Synthesis of progesterone receptors was stimulated by all doses of oestrogen studied. Concentrations of progesterone receptors were significantly higher after 3 and 5 days of treatment with 25 and 50 μg oestrogen. After 9 days of treatment, however, concentrations of progesterone receptors were virtually identical in all treated groups, including the group treated with OB. We have concluded that large doses of oestrogen significantly decrease oestrogen receptor content in the rat uterus, especially when OB is used. The degree of reduction, however, is only moderate under these experimental conditions and is insufficient to inhibit synthesis of progesterone receptors.
SECRETION OF LUTEINIZING HORMONE IN OVARIECTOMIZED ADULT RATS TREATED NEONATALLY WITH MONOSODIUM GLUTAMATE
Authors: DYER R. G. , WEICK R. F. , MANSFIELD S. , CORBET H.
Published: December 2008

We have studied the possible effects of monosodium glutamate (MSG) on LH secretion in ovariectomized rats.

In experiment 1 MSG-treated and control rats were given oestradiol benzoate at noon and 72 h later half the rats in each group were given a second injection of oestradiol benzoate or progesterone. Blood samples were taken immediately before and 6 h after these i.m. injections. At 78 h there were no significant differences in plasma LH concentration measured in the two groups of rats given progesterone or in the two groups given a second injection of oestradiol benzoate although for both MSG-treated and control rats progesterone produced a significantly (P < 0·01) greater LH surge than did oestradiol benzoate.

In experiment 2 100 μl blood samples were collected at 5-min intervals for up to 3 h from MSG-treated and control rats. For rats showing more than one pulsatile discharge of LH, peak and trough values for plasma LH concentrations were not significantly influenced by MSG treatment. However the mean pulse height was significantly (P < 0·001) greater in the MSG-treated group than in control rats. Pulsatile release stopped more quickly in the MSG-treated rats and their mean plasma LH concentration after 120 min of blood sampling was significantly (P < 0·05) lower than that obtained in the control animals.

Thus, although some aspects of LH secretion seem to be significantly different in MSG-treated rats, these effects may result from the greater sensitivity of the MSG-treated animals to experimental manipulation.
ONTOGENY OF THE SENSITIZING EFFECT OF OESTRADIOL AND LUTEINIZING HORMONE RELEASING HORMONE ON THE ANTERIOR PITUITARY GLAND OF THE FEMALE RAT
Authors: MEIDAN R. , FINK G. , KOCH Y.
Published: December 2008

The ontogeny of the facilitatory effect of oestradiol and luteinizing hormone releasing hormone (LH-RH) on the responsiveness of the anterior pituitary gland to LH-RH has been studied in vitro using pituitary glands from female rats aged 15, 17, 20, 31, 35 and 38 days. The facilitatory effect of oestradiol was already well established by day 15, while the facilitatory effect of LH-RH (priming effect) developed only after day 17. Although it increased the overall response of the gland to LH-RH, oestradiol did not selectively enhance the priming effect of LH-RH. Both the effect of oestradiol and LH-RH reached a peak on day 25, 7 days before vaginal opening in this colony, and, as assessed by measuring pituitary LH contents, were not dependent upon the synthesis of LH. These data show that different mechanisms may be involved in the facilitation of pituitary responsiveness by oestradiol and LH-RH, but that both mechanisms appear to depend more upon an increase in the sensitivity of the receptor/release apparatus rather than in the gonadotrophin content of the gonadotrophs.
A COMPARISON OF PREPARATIONS OF HIGHLY PURIFIED HUMAN PITUITARY FOLLICLE-STIMULATING HORMONE: DIFFERENCES IN THE FOLLICLE-STIMULATING HORMONE POTENCIES AS DETERMINED BY IN-VIVO BIOASSAY, IN-VITRO BIOASSAY AND IMMUNOASSAY
Authors: STORRING P. L. , ZAIDI A. A. , MISTRY Y. G. , FRÖYSA BERIT , STENNING BRIDGET E. , DICZFALUSY E.
Published: December 2008

The FSH potencies of 12 preparations of highly purified human pituitary FSH, originating from six different laboratories, were determined by in-vivo and in-vitro bioassays and by immunoassay in terms of the First International Reference Preparation of Human Pituitary Gonadotrophins (FSH and LH) for Bioassay (IRP; coded 69/104). The contamination of these FSH preparations with LH was also determined. Estimates of protein content were based on the absorbance at 280 nm of solutions of the preparations, assuming that A1%1 cm 280 = 10.

The FSH potencies varied between different preparations from 827 i.u./mg to 13 100 i.u./mg by in-vivo bioassay; from 2930 to 14 600 i.u./mg by in-vitro bioassay and from 1680 to 5690 i.u./mg by immunoassay. The ratios of in-vivo biological activity relative to in-vitro biological activity and to immunoreactivity respectively varied between preparations from 0·06 to 2·3 and from 0·15 to 4·1, and there was a significant positive correlation between each of these ratios and the in-vivo biological potency of the preparations; such differences could be due to varying degrees of sialylation between preparations. On the other hand the ratios of in-vitro biological activity to immunoreactivity between preparations were fairly constant (approx. 2). The excess biological activity relative to immunoreactivity observed, in terms of the IRP, in all these materials is consistent with recent findings of some immunoreactive FSH in the IRP unassociated with biological activity. These data did not demonstrate any significant advantage, in terms of FSH in-vivo biological potency, from the use of fresh-frozen rather than acetone-dried pituitary glands for the isolation of FSH.

Contamination of all these preparations with LH appeared to be less than 3% (w/w), as determined by in-vitro bioassay and by immunoassay.

The results of this study are discussed in relation to the selection of material for an international reference preparation for immunoassay and attention is drawn to the value of high in-vivo biological FSH potency as a criterion of the identity of a preparation as well as of its freedom from contaminants without FSH biological activity.
PLASMA CONCENTRATIONS OF OESTRONE, OESTRADIOL, OESTRIOL AND PROGESTERONE DURING MECHANICAL STRETCH-INDUCED ABORTION AT MID-TRIMESTER
Authors: MANABE Y. , MANABE A. , ASO T.
Published: December 2008

Plasma levels of unconjugated oestrone, oestradiol, oestriol and progesterone were serially studied in six uncomplicated patients in the mid-trimester of pregnancy before and during abortion induced by purely mechanical stretching of the uterus by laminaria and rubber balloon. Variability of these hormonal levels among patients was significant before the treatment. In four cases where the fetus was aborted alive, the plasma value of these hormones remained at a high level during the treatment with the exception of oestriol level in one case. In two early mid-trimester cases the fetus died during the treatment and plasma oestriol dropped significantly, while the level of the other hormones remained raised until fetal delivery. In these two cases the apparent onset of labour was noted before fetal death. It was concluded that the onset and progress of labour by mechanical stretching of the uterus is probably unrelated to the steroid hormones estimated in the present study.
EFFECT OF PROGESTERONE WITHDRAWAL IN SHEEP DURING LATE PREGNANCY
Authors: TAYLOR M. J. , WEBB R. , MITCHELL M. D. , ROBINSON J. S.
Published: December 2008

The concentration of progesterone in the peripheral plasma of seven sheep during late pregnancy was reduced by injection of an inhibitor of 3β-hydroxysteroid dehydrogenase activity. Concentrations of progesterone were 10·0± 1·0(s.e.m.) ng/ml (n = 6) before injection of the inhibitor, fell to 1·39 ± 0·40 ng/ml (n = 6) 30 min after injection, and remained within this lowered range for 6 h after injection. By 20–24 h and 30–35 h after injection progesterone concentrations had recovered to 4·63±0·94 and 14·07 ±4·17 ng/ml respectively (n = 6). Six out of seven ewes delivered prematurely 32·5± 2·9 h after injection. Delivery appeared to be normal, and was associated with increasing concentrations of 13,14-dihydro-15-oxo prostaglandin F2α in peripheral plasma. Concentrations of oestradiol-17β17β in peripheral plasma were slightly raised immediately before delivery, at which time progesterone concentrations were within the preinjection range. These data suggest that progesterone withdrawal is one mechanism that initiates increased prostaglandin F2α secretion in the pregnant sheep.
HYPOTHALAMIC SECRETION OF THYROTROPHIN RELEASING HORMONE IS DECREASED IN MALE JAPANESE QUAIL EXPOSED TO LONG DAILY PHOTOPERIODS
Authors: ALMEIDA O. F. X.
Published: December 2008

Adult male Japanese quail held under short daily photoperiods (8 h light: 16 h darkness; 8L : 16D) had significantly higher plasma concentrations of thyroid-stimulating hormone (TSH), tri-iodothyronine (T3) and thyroxine (T4) than did those kept under long days (16L : 8D).

When given a single s.c. injection of 50 μg thyrotrophin releasing hormone (TRH) the birds held under both the 8L : 16D and 16L : 8D photoperiods showed rapid increases in their blood concentrations of TSH, T4 and T3, the amplitude of the TSH response of the birds exposed to 16L : 8D being particularly marked. These results suggest that, in the male quail, long daily photoperiods produce a hypothyroid state as a result of diminished TRH secretion. The synthetic and secretory capacities of the thyroid gland and pituitary thyrotrophs are apparently unimpaired by long days.
NEUROTRANSMITTER EFFECTS ON RELEASE OF PROLACTIN AND GROWTH HORMONE IN VITRO FROM PITUITARY GLANDS OF THE PIGEON, COLUMBA LIVIA
Authors: HALL T. R.
Published: December 2008

Single pigeon anterior pituitary glands were incubated with or without a hypothalamus in media containing various drugs. Release of prolactin and growth hormone was quantified by an electrophoretic-densitometric method. The hypothalamus stimulated release of both prolactin and growth hormone from the pituitary gland. Dopamine did not affect hormone release from pituitary glands incubated alone, but inhibited hypothalamus-stimulated release of prolactin and augmented hypothalamus-stimulated release of growth hormone in a dose-related manner. The effects of dopamine were reversed by its antagonist, pimozide. Serotonin stimulated release of prolactin and inhibited release of growth hormone from pituitary–hypothalamus co-incubations, and these effects were blocked by its antagonist, methysergide. Thyrotrophin releasing hormone (TRH) stimulated release of both hormones directly from pituitary glands incubated alone. Dopamine now inhibited TRH-stimulated release of prolactin, without affecting TRH-stimulated release of growth hormone. These results indicate that the neurotransmitters, dopamine and serotonin, affect the in-vitro release of factors from the hypothalamus which control the secretion of prolactin and growth hormone. In addition, dopamine may inhibit release of prolactin directly from the pituitary gland, but only when secretion of prolactin is high initially.
PITUITARY AND PLASMA LEVELS OF LUTEINIZING HORMONE AND FOLLICLE-STIMULATING HORMONE IN MALE AND FEMALE RABBIT FETUSES
Authors: VEYSSIÈRE G. , BERGER M. , JEAN-FAUCHER CH. , DE TURCKHEIM M. , JEAN CL.
Published: December 2008

To study the ontogenesis of fetal pituitary gonadotrophin synthesis and release, LH and FSH were measured by radioimmunoassay in fetal rabbit pituitary glands and blood of both sexes from day 18 of gestation until birth. Results on levels of testicular and plasma testosterone were also included. Immunoreactive LH was first detected on day 19 in the pituitary gland and on day 20 in the plasma of fetuses of both sexes. Pituitary FSH was first measurable in both male and female fetuses at 24 days of gestation. Levels of FSH could not be detected in the blood of male fetuses at any time during gestation. In females, FSH could be measured in the circulation from day 27 of gestation until birth.

These results show that (1) the ontogeny of pituitary LH and the onset of testosterone secretion are closely correlated and take place between 18 and 20 days of gestation just before the beginning of differentiation of the male genital tract, and (2) the highest concentrations of pituitary LH and FSH are observed, in both sexes, in late gestation after days 24–25.
ANALYSIS OF GROWTH HORMONE GENES IN MICE WITH GENETIC DEFECTS OF GROWTH HORMONE EXPRESSION
Authors: PHILLIPS J. A. , BEAMER W. G. , BARTKE A.
Published: December 2008

Restriction endonuclease analysis of genomic DNA was carried out for three types of dwarf mice (Little, Ames dwarf and Snell dwarf) that have genetic defects in GH expression. We found the GH genes to be present in homozygotes for each mutant allele as well as in their control litter-mates. These three types of dwarf mice may be useful in studying the molecular basis of inherited GH deficiency and as models for analogous genetic disorders of human GH expression.
Metabolism of C19 steroids in vitro by the submaxillary salivary gland of mature and immature domestic pigs
Authors: Booth W. D.
Published: December 2008

Homogenates of the submaxillary glands of immature and mature pigs were incubated with 3H-labelled C19 steroids which have been shown previously to be metabolized in vitro by the submaxillary gland of mature boars. Dehydroepiandrosterone was metabolized largely to androstenedione, 5α-androstane-3,17-dione and androsterone, and to small amounts of testosterone, 5α-dihydrotestosterone and 5α-androstanediols. Testosterone yielded predominantly 5α-androstane-3α,17β-diol with smaller amounts of other 5α-reduced products, i.e. 5α-dihydrotestosterone, 5α-androstane-3β,17β-diol, 5α-androstane-3,17-dione and androsterone; 5α-dihydrotestosterone and the two epimeric 5α-androstane-3α/3β,17β-diols were interconverted. These and earlier results show that the porcine submaxillary gland has the capacity in vitro to metabolize selected C19 steroids in a way which is not related to either sexual maturity or sex of the animal; in this respect the findings support certain aspects of previous histochemical studies.
Further characterization of the molecular species formed during the biosynthesis of rat luteinizing hormone
Authors: Chowdhury M. , Grotjan H. E. , Steinberger E.
Published: December 2008

During the biosynthesis of rat LH (rLH) there are four molecular species found intracellularly: native rLH, a species which co-elutes with rLHα on Sephadex G-100, a species which elutes with an apparent molecular weight of approximately 21 000 and a large molecular weight form (excluded from Sephadex G-100). Significant quantities of native rLH and rLHα are secreted. The species of large molecular weight binds to Concanavalin A–Sepharose suggesting that it is glycosylated. The 21 000 molecular weight rLH-like molecule has tentatively been identified as an rLH subunit which has not been completely processed.
Corticoliberin and somatoliberin activity in the pituitary stalk median eminence of rats after neonatal treatment with monosodium glutamate
Authors: Ács Zsuzsanna , Antoni F. A. , Makara G. B.
Published: December 2008

Neurotoxic lesions of the arcuate nucleus by neonatal treatment with monosodium glutamate (MSG) resulted in a decrease of plasma GH levels without affecting plasma corticosterone concentration. The corticoliberin activity of the pituitary stalk median eminence (SME) in MSG-treated animals was similar to that of litter-mate controls. Growth hormone releasing (somatoliberin) activity of the SME, tested after placing an anterolateral cut around the medial basal hypothalamus, was significantly lower in MSG-treated than in control animals. It was concluded that a substantial proportion of the somatoliberin neurones are found in the arcuate nucleus.