bluuebunny/crossref_metadata_2025 huggingface dataset:
Influence of morphine during pregnancy on neuroendocrine regulation of pituitary hormone secretion
Authors: Litto W. J. , Griffin J. P. , Rabii Jamshid
Published: December 2008

The effects of exposure to morphine during pregnancy on postnatal neuroendocrine systems were investigated. Rats received morphine sulphate or 0·9% (w/v) NaCl twice daily on days 5–12 of pregnancy. A dose of 5 mg morphine sulphate/kg was administered for the first three injections while 10 mg/kg was used for each of the remaining 13. This treatment regimen led to a significant delay in the onset of vaginal opening in the female offspring. Mothers treated with morphine sulphate showed a marked attenuation of their prolactin response to the suckling stimulus, although they still released significant amounts of the hormone. Both male and female offspring of the opiate-treated dams showed a major reduction in the sensitivity of their hypothalamic-pituitary axis to gonadal steroids at 15 days of age. No significant differences were found in the acute thyrotrophin response to single injection of morphine sulphate of prepuberal male and female pups of morphine- and saline-treated dams. These data show that exposure to opiates during critical periods of prenatal development lead to long-lasting alterations in the neuroendocrine control systems of the animal. These alterations may then have significant consequences on the physiological maturation and adult behaviour of the animal.
Dynamic 131I-labelled insulin distribution in rabbits as seen by in-vivo scintigraphic studies
Authors: Bourgeois P. , Frühling J. , Langohr M. , Coel J. , Verbist A. , Ghanem G. , Legros F.
Published: December 2008

The kinetics of 131I-labelled insulin distribution in heart, liver, kidneys and urinary bladder of rabbits were studied in vivo by gamma-camera techniques combined with plasma measurements (glucose concentrations and chromatographic separation of insulin and its degradation products). The distribution space of radioiodinated insulin differed from the vascular bed delineated by radioiodinated serum albumin. During a 20-min gamma-camera recording, radioactive degradation products only appeared in the plasma after 10–12 min. Previous administration of a 10 000-fold excess of unlabelled insulin and 5 ml glucose (20%) did not modify the evolution of 131I-labelled insulin cardiac invasion and the subsequent linear decrease of radioactivity. Conversely, wash-out of radioactivity from the liver and kidney was accelerated after preadministration of this excess of unlabelled hormone, binding in these organs accounting for this acceleration. Urinary bladder filling was imaged later than cardiac, hepatic or renal labelling and was only accelerated by polyuria induced by glucose injection, independent of preadministration of unlabelled hormone.
Differences in prostaglandin E2, prostaglandin F2α and prostacyclin contents and their response to thyrotrophin stimulation and in prostaglandin-stimulated cyclic AMP response in normal and Graves's thyroid slices
Authors: Takasu Nobuyuki , Takahashi Kazunori , Ishigami Tatsuro , Yamada Takashi , Sato Seiya
Published: December 2008

The human thyroid contained prostaglandin (PG) E2, PGF2α and 6-oxo-PGF1α, an end-metabolite of prostacyclin (PGI2), the 6-oxo-PGF1α content being the highest of these prostaglandins. Graves's thyroid contained a significantly higher amount of PGF2α and lower amounts of PGE2 and 6-oxo-PGF1α than the normal thyroid. Thyrotrophin acutely augmented the thyroid contents of PGE2, PGF2α and 6-oxo-PGF1α. The TSH-stimulated increases in PGE2 and 6-oxo-PGF1α were lower but the TSH-stimulated increase in PGF2α was significantly higher in Graves's thyroid than in the normal thyroid. Prostaglandin E2 and PGI2 stimulated human thyroid cyclic AMP synthesis, with the magnitudes of PGE2-and PGI2-stimulated increases in cyclic AMP being equal in normal and Graves's thyroid. Prostaglandin E2α did not stimulate cyclic AMP synthesis significantly.

These results provide evidence that prostaglandins play important roles in thyroid physiology and the pathophysiology of Graves's disease.
Control of follicle-stimulating hormone secretion by steroid-free bovine follicular fluid in the ovariectomized rat
Authors: Koiter T. R. , van der Schaaf-Verdonk G. C. J. , Kuiper H. , Pols-Valkhof N. , Schuiling G. A.
Published: December 2008

The effects of steroid-free bovine follicular fluid (bFF) and sodium phenobarbitone on spontaneous LH releasing hormone (LHRH)-induced secretion of FSH and LH were studied in ovariectomized rats. Luteinizing hormone releasing hormone was administered by infusion to rats anaesthetized with phenobarbitone. Bovine follicular fluid reduced FSH release and synthesis. Luteinizing hormone release remained unaffected after bFF treatment. Phenobarbitone reduced both FSH and LH release. The observed suppressive effects of bFF and phenobarbitone on FSH secretion were additive, suggesting that the basal release of FSH has an LHRH-dependent and an LHRH-independent component. Furthermore, bFF did not affect pituitary responsiveness of LH secretion to LHRH and reduced the responsiveness of FSH secretion only when administered some time before the LHRH challenge. The present observations support the view that in the ovariectomized rat the pituitary gland is the only site of action of inhibin-like activity as present in bFF.
A direct anabolic effect of progesterone in the intact female rat
Authors: Shirling D. , Ashby J. P. , Baird J. D.
Published: December 2008

Rats implanted with progesterone gained weight more rapidly than controls and had a greater percentage of total body fat. The dietary intake of hormone-treated animals was restricted to control levels. The food was supplied in small quantities at regular intervals over a 24-h period with the aid of automatic feeding machines. The observed changes in body weight and composition are therefore not related to either an increased intake of energy or a change in the pattern of feeding after implantation.
Extraction of androgen–receptor complexes from regions of rat ventral prostate nuclei sensitive or resistant to nucleases
Authors: Davies P.
Published: December 2008

Rat ventral prostate nuclei contain androgen-binding sites which are susceptible or resistant to excision by endonucleolytic action. Those which were susceptible were associated both with oligonucleosomal and subnucleosomal particles. The sedimentation profile characteristic of a nuclear androgen-receptor complex could be obtained by exhaustive nucleolytic digestion or by treatment of fractions with KCl (0·6 mol/l). Androgen-binding sites resistant to DNAase I were also resistant to KCl, whereas those sites resistant to micrococcal nuclease were partially extractable with KCl. Nuclease-resistant sites could be extracted with heparin (10 mg/ml). Androgen–receptor complexes obtained from nuclease-sensitive or nuclease-resistant regions by extraction with KCl or heparin were indistinguishable by routine sedimentation analysis.
Release of vasopressin in response to hypoxia and the effect of aminergic and opioid antagonists
Authors: Forsling M. L. , Aziz L. A.
Published: December 2008

Plasma vasopressin, arterial blood gas tensions, pH, arterial blood pressure, heart rate and respiration were monitored in conscious rats breathing room air or exposed to varying degrees of hypoxia. A similar series of observations was made in a group of anaesthetized rats and in rats treated with α- and β-adrenergic and dopaminergic blocking agents. The effect of two opioid antagonists on the vasopressin response was also noted. Hypoxia produced an increase in circulating vasopressin concentrations in both conscious and anaesthetized rats. In the conscious animals the increase reached statistical significance when the animals were exposed to 12% oxygen in nitrogen, which produced a fall in arterial PaO2 of 44·7 ± 5·0%. Guanethidine, phentolamine and propranolol all produced a significant fall in the basal concentrations of vasopressin, while guanethidine, phenoxybenzamine and propranolol blocked the increase seen on breathing 12% oxygen in nitrogen. Naloxone and levallorphan also reduced the vasopressin response to hypoxia. Thus it appears that aminergic pathways play a role in the maintenance of circulating concentrations of vasopressin and in the response to hypoxia. Endogenous opioids also appear to be involved in the hypoxic response.
Action of multiplication-stimulating activity on [3H]thymidine incorporation in rabbit and human fetal chondrocytes in vitro
Authors: Ashton I. K. , Pocock A. E.
Published: December 2008

The mitogenic action of multiplication-stimulating activity (MSA) on normal mammalian chondrocytes has been examined. Addition of MSA (NIH, PkII-MSA, 2·5–500 ng/ml or Collaborative Research, CR-MSA, 50–250 ng/ml) to primary suspensions of chondrocytes prepared by enzymic digestion of costal and articular cartilage of rabbits (356–481 g body wt) resulted in a dose-dependent increase in [3H]thymidine incorporation into the trichloroacetic acid-precipitated cell contents. CR-MSA (50–250 ng/ml) also had a significant stimulatory effect on [3H]thymidine incorporation into human fetal chondrocytes (22 weeks of gestation) prepared by enzymic digestion. When PkII-MSA was added in the presence of 1·25% of a standard adult or cord plasma to either rabbit or human fetal (18 weeks) chondrocytes, the increase in [3H]thymidine incorporation appeared to be synergistic. The mitogenic action of MSA can thus be demonstrated on primary suspensions of mammalian chondrocytes. The action of MSA on human chondrocytes has not previously been reported.
Oestrogen levels in the blood, not in the uterus, determine uterine eosinophilia and oedema
Authors: Tchernitchin A. N. , Galand P.
Published: December 2008

This work was aimed at testing whether oestrogen-induced changes in the uterus are responsible for uterine eosinophil migration or whether the effect is due to a direct action of oestrogen on the eosinophils themselves. Uterine eosinophil migration in response to intraluminal administration of oestradiol-17β into one uterine horn was measured in the injected and in the untreated contralateral horns. Uterine genomic responses (luminal epithelial and myometrial hypertrophy and nucleolar enlargement), known to depend on the local intra-uterine oestrogen level, were measured to control for the absence of hormone recirculation to the uninjected horn. The effects of intravenously administered oestradiol were also determined. Intraluminal injection of 0·1 ng oestradiol had no effect on either horn. With 10 ng, only the injected horn exhibited the genomic responses while eosinophilia developed to the same extent in both horns. With 100 ng, the genomic responses and eosinophilia were identical in injected and in contralateral horns. The results show that eosinophil migration depends on systemic levels of oestrogen, thus indicating that it is due to an oestrogen-induced change in a property of eosinophil leukocytes rather than a change in the uterus itself. As water imbibition showed the same pattern of responses as eosinophilia, this lends further support to the hypothesis of a role for eosinophils in oestrogen-induced uterine oedema.
Seasonal and circadian changes of testosterone levels in the peripheral blood plasma of stallions and their relation to semen quality
Authors: Byers S. W. , Dowsett K. F. , Glover T. D.
Published: December 2008

Three stallions were bled each hour for 25 h at 28-day intervals throughout 1 year. Testosterone levels were pulsatile. Pulse frequency and pulse amplitude were higher in the summer months than at other times (P<0·01). The number of testosterone pulses also varied throughout the day, with the greatest frequency occurring in the afternoon (14.00–17.00 h) and at night (22.00–01.00 h). Mean testosterone levels were highest in the summer (P<0·01) but showed a secondary, smaller increase in the autumn. Semen characteristics were assessed from measurements of 222 stallions. Semen volume was greatest in the summer (P<0·01) but both the concentration (P<0·01) and the total number of spermatozoa per ejaculate (P<0·05) were highest in the autumn. These results show that the highest testosterone concentrations in peripheral plasma are not necessarily associated temporally with optimum semen quality.
The pineal gland and the photoperiodic control of luteinizing hormone secretion in intact and castrated Japanese quail
Authors: Simpson S. M. , Urbanski H. F. , Robinson J. E.
Published: December 2008

The effects of pinealectomy on a range of photoperiodic responses were investigated in male Japanese quail by measuring plasma LH concentrations in intact, sham-operated and pinealectomized birds in the following four experiments: (1) transfer of sexually quiescent birds from a short photoperiod of 8 h light: 16 h darkness (8L: 16D) to a photostimulatory daylength of 16L: 8D; (2) transfer of sexually mature birds from 16L: 8D to 8L: 16D; (3) castration in 16L: 8D and exposure to 13L: 11D; (4) castration in 8L: 16D and exposure to 13L: 11D. There was no evidence of effects of the pineal gland on the photoperiodically induced changes in LH secretion, the quantitative relationship between LH secretion and photoperiod in intact and castrated birds, or the induction of relative photorefractoriness by prolonged exposure to 16L: 8D. This suggests that there is no pineal influence on the photoperiodic clock or its effectors in this bird.
Effects of prolactin on testicular functions using an intratesticular pituitary graft
Authors: Weber R. F. A. , Ooms M. P. , Vreeburg J. T. M.
Published: December 2008

Pituitary glands were grafted under the capsule of the left testis of rats to induce high levels of prolactin in this organ. One hundred days after implantation, significantly increased levels of prolactin were found in the tissue and the venous plasma of the left testis. Although the levels of testosterone in testicular venous plasma were not raised, the testicular content of testosterone was increased when compared to the right testis. The ratio of testosterone and dihydrotestosterone was not affected in the pituitary-grafted testis.

Since the seminiferous tubules adjacent to the pituitary graft appeared to be completely normal, it is concluded that in the rat high levels of prolactin have no direct inhibitory effect on testicular functions.
Plasma oestradiol-17β and testosterone concentrations as possible causes of the infertility of congenitally obese Zucker rats
Authors: Whitaker E. M. , Shaw M. A. , Hervey G. R.
Published: December 2008

The plasma oestradiol-17β concentrations of obese and non-obese female Zucker rats have been measured in three phases of the oestrous cycle. The oestradiol concentrations of both phenotypes were similar, and changed normally with the oestrous cycle. The weights of the uteri also changed normally with the cycle. Plasma androgen concentrations in male Zucker rats have also been measured: the mean concentration was slightly but significantly lower in obese rats, and androgen-sensitive tissues were slightly reduced in weight. The oestradiol-17β concentrations in males of both phenotypes were similar. It seems unlikely that deficient plasma concentrations of gonadal hormones cause the infertility of obese rats of either sex.
Effects of long-term treatment with LH on induction of cyclic ovarian activity in seasonally anoestrous ewes
Authors: McNatty K. P. , Hudson N. , Gibb M. , Ball K. , Fannin J. , Kieboom L. , Thurley D. C.
Published: December 2008

The aim of the present study was to establish whether cyclic ovarian activity could be induced and then maintained in anoestrous Romney ewes by the long-term administration of regular intravenous pulses of LH (10 μg ovine LH i.v. once every 1 or 2 h for 29–91 days). The LH pulse regimen was designed to generate plasma profiles of LH that were comparable to those experienced during the luteal and follicular phases of the oestrous cycle.

The results showed that the LH treatments were capable of inducing cyclic ovarian activity, as assessed from the concentrations of progesterone in plasma, but that the treatments were inadequate for sustaining cyclic activity beyond two consecutive progestational phases. After 35–56 days of treatment, the plasma concentrations of FSH declined significantly (P <0·05) relative to those in the untreated animals. These data suggest that FSH supplementation as well as LH might be required for the long-term maintenance of cyclic ovarian activity in seasonally anoestrous ewes.

J. Endocr. (1984) 100, 67–73
Aldosterone effects on water and electrolyte metabolism
Authors: Kenyon C. J. , Saccoccio N. A. , Morris D. J.
Published: December 2008

The effects of constant infusions of small doses of adrenal steroid hormones on sodium, potassium and water metabolism were studied in male adrenalectomized rats. An infusion of 1 μg aldosterone/day was sufficient to restore normal sodium and potassium balance in a group of rats fed an unsupplemented diet. Log doses of aldosterone (0·1–10 μg/day for 4 days) administered some days after adrenalectomy caused linear increases in the body weight of rats fed a sodium-supplemented diet (0·05 m-NaCl as drinking fluid) during 4 days of treatment. Increases in body weight correlated with renal sodium and water balance.

When steroid treatment was started at the time of adrenalectomy, sodium balance was not significantly affected although rats treated with 1 μg aldosterone/day ate more, drank less saline, produced a smaller volume of urine of greater osmolarity and gained more weight than controls. A dose of 100 μg 18-hydroxy-deoxycorticosterone/day had no significant effects. Fluid intake and urine volume were not significantly affected by 1 mg corticosterone/day but food intake, water balance and weight gain were greater than controls. Rats treated with both aldosterone and corticosterone showed a decrease in free water clearance. Aldosterone and corticosterone, both singly and in combination, reduced plasma potassium levels. Plasma sodium levels were only increased when aldosterone was administered on its own.

Long-term steroid infusions have revealed more about the physiology of aldosterone action than could acute measurements of renal function. In particular, they have indicated that dietary intake of electrolytes as well as excretion are affected, that mineralocorticoid actions are distinct from glucocorticoid actions and that there are transient effects of aldosterone on fluid regulation which are not sustained under steady-state conditions.

J. Endocr. (1984) 100,93–100
Modulation of rat pituitary gonadotrophin secretion by porcine granulosa cell 'inhibin', LH releasing hormone and sex steroids in rat anterior pituitary cells in culture
Authors: Massicotte J. , Lagacé L. , Godbout M. , Labrie F.
Published: December 2008

The incubation of female rat adenohypophysial cells in primary culture with porcine granulosa cell culture medium (GCM) led to the complete inhibition of responses of LH and FSH to LH releasing hormone (LHRH) as well as to the inhibition of spontaneous release of FSH. These effects of GCM suggest the specificity of the 'inhibin'-like activity of this material. Granulosa cell culture medium completely reversed the stimulatory effect of oestradiol-17β on the responses of LH and FSH to LHRH, as well as reversing the stimulatory effect of progesterone, oestradiol or a combination of both steroids on the spontaneous release of FSH, while not affecting the spontaneous release of LH. The antioestrogenic effects of progesterone observed on the response of LH to 0·3 nm-LHRH were amplified in the presence of GCM while the stimulatory effects of progesterone, oestradiol or both on the response of FSH to 0·3 nm-LHRH were completely reversed by the medium. Moreover, the presence of GCM led to an additive inhibitory effect with dihydrotestosterone on the response of LH to LHRH while it completely reversed the stimulatory effect of the androgen on spontaneous and LHRH-induced FSH release. The present data show that the presence of porcine granulosa cell 'inhibin' activity can exert marked interactions with sex steroids in the control of gonadotrophin secretion. This 'inhibin' activity reversed all the stimulatory effects and potentiated all the inhibitory effects of sex steroids on gonadotrophin secretion. Although the physiological role of 'inhibin' remains to be defined well, the importance of this activity is clearly demonstrated in anterior pituitary cells in culture.

J. Endocr. (1984) 100, 133–140
Plasma concentrations of oestradiol and oestrone during perinatal development in male and female ferrets
Authors: Erskine M. S. , Baum M. J.
Published: December 2008

The concentrations of oestradiol and oestrone in peripheral plasma of male and female ferrets 5 days before and 7, 15 and 30 days after birth were measured. Both steroids were present in high concentrations prenatally. Much lower levels were found in samples collected on day 7 and later, when the concentrations were similar to those of adult gonadectomized animals. No significant sex difference was seen for the concentration of either steroid at any age studied. These results, and those previously reported showing the absence of a circulating binding protein and the presence of oestradiol receptors in the hypothalamus in the perinatal period in this species, suggest that brains of both males and females are exposed to significant amounts of oestrogen during development. These findings lend support to the possibility that prenatal exposure to oestrogen plays a role in organizing the potential for female behaviour in male and female ferrets.

J. Endocr. (1984) 100, 161–166
Effects of gonadectomy on seasonal changes in plasma LH and prolactin concentrations in male and female starlings (Sturnus vulgaris)
Authors: Dawson A. , Goldsmith A. R.
Published: December 2008

Intact and gonadectomized male and female starlings (Sturnus vulgaris) were held in outdoor aviaries for 1 year. Blood samples were taken frequently and assayed for LH and prolactin, and intact males were laparotomized to determine testis size.

Changes in testis size in intact males were similar to those in wild starlings with maximum size during April. Hormone levels in intact males and females also followed a similar pattern to those in wild birds although absolute levels were somewhat lower. Levels of LH increased during spring, were highest in early May and then declined rapidly as birds became photorefractory. Prolactin levels did not begin to increase until April, reached a peak in late May and then declined. In gonadectomized males and females, high levels of LH were maintained throughout the early part of the year when birds were photosensitive, but declined rapidly as they became photorefractory. This occurred at the same time as in intact birds. During photorefractoriness, LH levels in gonadectomized birds were similar to those in intact birds. Prolactin showed the same seasonal pattern in gonadectomized birds as that in intact birds. These results demonstrate that gonadal steroid feedback is unimportant in initiating and maintaining photorefractoriness and confirm that increased prolactin secretion coincides with the onset of photorefractoriness.

J. Endocr. (1984) 100, 213–218
Relationship between endogenous opioids and the oestrous cycle in the rat
Authors: Hulse G. K. , Coleman G. J. , Copolov D. L. , Clements J. A.
Published: December 2008

The aim of this study was twofold: (1) to document changes in levels of immunoreactive β-endorphin (Ir-β-EP) in the hypothalamus, anterior pituitary gland, neurointermediate lobe and plasma during the oestrous cycle of the rat and (2) to investigate stress-induced changes in plasma Ir-β-EP at different stages of the oestrous cycle. Evidence was found that Ir-β-EP levels in the hypothalamus, anterior pituitary gland and plasma are not constant during the oestrous cycle and that the Ir-β-EP response to stress is a function of the phase of the oestrous cycle at which stress is applied. It is suggested that fluctuations in ovarian hormones may influence oestrous Ir-β-EP levels both under normal conditions and after exposure to stress.

J. Endocr. (1984) 100, 271–275
In-vivo and in-vitro secretion of prolactin by lactating rat adenohypophyses as a function of intracellular age
Authors: Mena F. , Martínez-Escalera G. , Clapp C. , Grosvenor C. E.
Published: December 2008

Adenohypophysial prolactin of lactating rats was pulse-labelled by [3H]leucine injected i.v. at the time of removal of the pups. The [3H]prolactin concentration in the pituitary gland, analysed by polyacrylamide-gel electrophoresis, progressively fell as the time from labelling to removal of the pituitary gland increased from 8 to 24 h, which suggests that there was a loss of hormone as it aged within the gland. Suckling effectively provoked the depletion–transformation of total and [3H]prolactin (extracted at pH 7·2) when applied after 8 h but not when applied after either 16 or 24 h after removing the pups.

In rats whose pups were removed for 8 h, suckling also depleted–transformed [3H]prolactin labelled 4 h, but not that labelled 1 h before suckling. The pituitary glands of other lactating rats were labelled with [3H]leucine injected i.v. at various times before removing the glands and incubating them in medium 199. The secretion into the medium of [3H]prolactin labelled either 4, 8, 16 or 24 h beforehand was maximal during the first 30 min then declined from 30 to 240 min of incubation. However, secretion of prolactin labelled 1 h and 10 min beforehand reached a maximum after 0·5–1 h and 2 h of incubation respectively, then remained constant during the remainder of the 4-h incubation period. The total 4-h secretion of [3H]prolactin was greatest (65% of preincubation concentration) from those glands labelled 4 h before in contrast to those labelled 10 min (15%) or 1 (38%), 8 (34%), 16 (18%) or 24 h (26%) before incubation. Taken together, these data suggest that prolactin synthesized 4 h earlier is more likely to be released in response to physiological stimuli than is more recently formed prolactin or prolactin which has remained in the pituitary gland for 16 h or longer.

J. Endocr. (1984) 101, 27–32
Development of a microtitre plate enzyme immunoassay for the determination of progesterone
Authors: Munro C. , Stabenfeldt G.
Published: December 2008

A rapid, solid-phase microtitre plate enzyme immunoassay (EIA) for progesterone is described using progesterone 3-O-carboxymethyloxime–horseradish peroxidase as the label and an antiserum raised in rabbits to a progesterone 11α-hemisuccinyl–bovine serum albumin immunogen. A competitive reaction was used with a reaction time of 2 h. Antibody-bound and free steroid were separated in a simple washing step of the antibody-adsorbed well surface. 2,2′-Azino-di-(3-ethylbenzthiazoline sulphonic acid) diammonium salt was used as the substrate with a reaction time of 1 h. A lower limit of sensitivity of 0·25 pg/well was obtained with the response being linear (logit/log) through 1000 pg/well. Results obtained by EIA and radioimmunoassay in several species gave excellent agreement (r = 0·98). This assay system allows accurate determination of progesterone in plasma with good specificity, precision and accuracy, and is suitable for the rapid assessment of luteal function and reproductive status in both clinical and research situations in a wide variety of species.

J. Endocr. (1984) 101, 41–49
Development and characterization of a radioimmunoassay to measure human tissue kallikrein in biological fluids
Authors: Bagshaw A. F. , Bhoola K. D. , Lemon M. J. C. , Whicher J. T.
Published: December 2008

A direct radioimmunoassay has been developed to measure tissue kallikrein in human biological fluids. These fluids include serum, plasma, urine, pancreatic juice and saliva. Purified kallikreins from human urine and human saliva were used to raise rabbit antibody and each was labelled with Na125I for use in the radioimmunoassay. A comparison of the different antigen-antibody systems was then made. Bound and free enzyme were separated by a double-antibody technique. The usable range of the standard curve was from 2·5 to 100 μg kallikrein/l. The intra-assay coefficient of variation was 4·7%, the interassay coefficient of variation 8·9% and the recoveries of purified kallikrein added to the samples were 99·3, 96·0, 110·8 and 81·2% for urine, saliva, serum and plasma respectively.

Parallel dilution curves were obtained for serum and plasma, as well as for urine, saliva and pancreatic juice. However, plasma anticoagulated with EDTA or heparin gave consistently lower values than serum, when measured in the radioimmunoassay. From eight different subjects plasma (EDTA) values were on average 50% lower than those of serum. Experiments designed to determine the cause of this difference revealed that treatment of blood with some anticoagulants, in particular heparin and EDTA, resulted in a marked reduction in the amount of measurable tissue kallikrein.

J. Endocr. (1984) 101, 173–179
Effect of immunoneutralization of LH releasing hormone on LH, FSH and ovarian steroid secretion in the preovulatory phase of the oestrous cycle in the ewe
Authors: McNeilly A. S. , Fraser H. M. , Baird D. T.
Published: December 2008

Immunoneutralization of LH releasing hormone (LHRH) by the i.v. administration of LHRH antiserum in the preovulatory period in the ewe resulted in a prompt abolition of the pulsatile secretion of LH without alteration of basal plasma levels of LH. This resulted in an immediate cessation of the pulsatile secretion of ovarian oestradiol, with no change in the secretion rate of androstenedione or plasma levels of FSH. The ovarian secretion rate of testosterone increased significantly.

Twenty to 22 h after the injection of LHRH antiserum, pulsatile secretion of LH and ovarian oestradiol and androgen secretion remained suppressed while plasma levels of FSH had increased significantly. The bolus injection of ovine LH (10 μg, i.v.) at this time caused a significant increase in oestradiol, androstenedione and testosterone, these responses being inversely related to the titre of LHRH antiserum in the plasma at this time.

These results show that (1) the secretion of oestradiol from the preovulatory sheep follicle is entirely dependent on the pulsatile secretion of LH and (2) since the secretion of ovarian androgens was not inhibited, LH may exert a short-term control over the aromatase enzyme system controlling the conversion of androgen to oestrogen in the granulosa cell of the preovulatory sheep follicle.

J. Endocr. (1984) 101, 213–219
Results of cyproheptadine treatment in dogs with pituitary-dependent hyperadrenocorticism
Authors: Stolp R. , Croughs R. J. M. , Rijnberk A.
Published: December 2008

Administration of cyproheptadine for 2 months to five dogs with pituitary-dependent hyperadrenocorticism (PDH) at a dose rate of 0·3 mg/kg per 24 h (group 1) and to four dogs with PDH at a dose rate of 1 mg/kg per 24 h (group 2) did not result in any clinical improvement. The hyperadrenocorticoid state, as indicated by the circulating cortisol levels, the urinary corticosteroid excretion and the response of the hypothalamo-pituitary-adrenal axis to lysine-vasopressin, thyrotrophin releasing hormone and dexamethasone did not change consistently, although there was a tendency to normalization of some parameters in the dogs of group 2. However, these changes were not found to be consistent for each individual dog but were limited to one parameter per dog. It is concluded that cyproheptadine is not suitable for the treatment of PDH in the dog.

J. Endocr. (1984) 101, 311–314
Effects of hypophysectomy and metyrapone on the catecholamine content and volumes of adrenaline- and noradrenaline-storing cells in the rat adrenal medulla
Authors: Coupland R. E. , Tomlinson A. , Crowe J. , Brindley D. N.
Published: December 2008

Using morphometric analysis and high-pressure liquid chromatography with electrochemical detection of catecholamines the volumes of adrenaline-storing (A) and noradrenaline-storing (NA) cells and the adrenaline and noradrenaline contents of adrenal glands of normal and age-matched hypophysectomized rats were determined and compared. Some hypophysectomized rats were also administered 150 mg metyrapone/kg daily for a 4-week period.

Hypophysectomy resulted in an increase in noradrenaline storage in adrenal glands. This was more marked in hypophysectomized animals not treated with metyrapone even though the combination of metyrapone and hypophysectomy resulted in a reduction of blood corticosterone concentration to only ∼ 6% normal.

There was no evidence of a change in proportion of A and NA cells in the adrenal medulla of hypophysectomized rats or hypophysectomized animals treated with metyrapone and it is concluded that the changes in amine concentrations and proportions observed reflect an increase in the storage of noradenaline in A cells as a consequence of less efficient methylation of noradrenaline after hypophysectomy.

The findings also showed that the left adrenal gland and medulla was usually slightly larger and had a greater catecholamine content and slightly higher proportion of NA cells than the right adrenal gland. During the period of the experiment (animals aged 6–15 weeks) there was an increase in the concentration of both adrenaline and noradrenaline in the normal adrenal glands. In normal Sprague—Dawley rats weighing 140 and 400 g the adrenal medulla accounted for some 5% of adrenal volume; this increased to 13% after hypophysectomy; A and NA cells together accounted for 50–60% of the volume of adrenal medulla.

J. Endocr. (1984) 101, 345–352
Characteristics of corticosteroid inhibition of adrenocorticotrophin release from the anterior pituitary gland of the rat
Authors: Mahmoud S. N. , Scaccianoce S. , Scraggs P. R. , Nicholson S. A. , Gillham B. , Jones M. T.
Published: December 2008

The occurrence and nature of corticosteroid inhibition of ACTH secretion at the rat anterior pituitary gland was investigated using three experimental models: animals bearing lesions of the basal hypothalamus, and two preparations of the gland incubated in vitro; these were tissue segments and collagenase-dispersed cells. Release of ACTH in the experiments was provoked using one of three distinct stimuli: acid extracts of whole hypothalami, corticotrophin releasing activity released by serotonin from hypothalami incubated in vitro and synthetic ovine corticotrophin releasing factor. Irrespective of whether ACTH was measured directly by radioimmunoassay (in the experiments in vitro) or indirectly in terms of corticosterone production (in the lesioned animals), its stimulated release from the anterior pituitary gland was inhibited by corticosterone. Two phases of inhibition were observed; these had some of the characteristics inferred previously from experiments with intact animals and designated fast feedback and delayed feedback.

However, the fast feedback demonstrable in lesioned animals did not show the rate-sensitivity shown previously in intact animals. 11-Deoxycortisol (or 11-deoxycorticosterone) and prednisolone proved to be agonists of corticosterone in provoking fast feed-back in lesioned animals, whereas they had been shown respectively to act as an antagonist or to have no effect in intact rats. Several steroids were able to cause delayed feedback in lesioned rats, but beclomethasone dipropionate (shown to be an agonist of corticosterone in intact rats) proved to have no inhibitory effect at the anterior pituitary gland of lesioned animals.

It is concluded that the dynamics of corticosteroid feedback mechanisms at the anterior pituitary gland, as indicated by experiments in lesioned animals, differ from those operative in the intact animals. Other work suggests that a more important site for such inhibitory mechanisms in vivo is the hypothalamus.

J. Endocr. (1984) 102, 33–42
Use of the perifusion technique on rat thyroid fragments in the study of thyroid hormone secretion: short-term effects of thyrotrophin, theophylline and glucagon
Authors: Attali J. R. , Darnis D. , Valensi P. , Weisselberg C. , Sebaoun J.
Published: December 2008

Perifusion of rat thyroid fragments was performed to study short-term effects of TSH, theophylline and glucagon on thyroid hormone secretion. This technique proved to be relatively convenient and sensitive, and gave reproducible results for at least 3 h, permitting precise kinetic studies of response to hormonal and pharmacological agents without any interference. There was a significant (P < 0·001) linear correlation between the log TSH concentrations over the range 20–150 mu./ml and thyroid response. A second stimulation, using the same concentration of TSH, did not differ from the first stimulation if they were separated by an active 'washing' period of only 15 min. Theophylline also had a stimulating effect and like TSH induced an early release of the hormone fraction with a peak between 2 and 4 min, but it did not potentiate the TSH effect.

Perifusion of rat thyroid fragments was found to be a useful tool for analysing dynamic effects of various substances. These effects were significant for periods of time as short as 20 min. Each thyroid preparation could be used a second time for another pharmacological or hormonal test. Our preliminary results also suggested that there was a direct glucagon effect on thyroid hormone secretion with a dose–response correlation.

J. Endocr. (1984) 102, 43–48
The role of steroid hormones, prolactin and placental lactogen on mammary gland development in ewes and heifers
Authors: Schams D. , Rüsse I. , Schallenberger E. , Prokopp S. , Chant J. S. D.
Published: December 2008

In the first part of the investigations the interaction between oestradiol-17β, progesterone and prolactin on the formation of the lobuloalveolar structure of the mammary gland was studied in 21 nulliparous intact postpubertal ewes. Tissue specimens of the mammary gland were evaluated by light microscopical examination and prolactin was measured in blood samples. Combined treatment with oestradiol and progesterone induced physiological development of the lobuloalveolar structure of the mammary gland in the presence of prolactin. Suppression of prolactin by bromocriptine prevented this effect. Treatment with progesterone alone was not effective and revealed histological structures comparable to the controls. The interaction of oestradiol-17β with prolactin appears to be a main trigger for mammary gland development.

In the second part of the investigations the effect of bromocriptine treatment during pregnancy on mammary gland development was studied in primigravid ewes and heifers. Mammary gland specimens were obtained for light and electron microscopical evaluation in ewes and heifers 5 and 10 days respectively before the expected date of parturition. Concentrations of prolactin and ovine placental lactogen were determined by radioimmunoassay. Bromocriptine treatment suppressed prolactin concentrations in ewes to minimal values but did not affect ovine placental lactogen concentrations. The histological evaluation revealed almost comparable stages of mammogenesis in both ewes and heifers. This effect can be attributed, at least in ewes, to the action of placental lactogen on mammogenesis. Placental lactogen might therefore be of physiological relevance during mammogenesis.

J. Endocr. (1984) 102, 121–130
Sexual inhibition in a prosimian primate: a pheromone-like effect
Authors: Schilling A. , Perret M. , Predine J.
Published: December 2008

The effect of dominant urine odour on plasma levels of testosterone and cortisol was studied in the prosimian primate Microcebus murinus. This species shows a photoperiod-dependent cycle of sexual activity. In particular, mean testosterone levels vary from 15 nmol/l during the annual rest period to 245 nmol/l during the breeding season. When males of this solitary and territorial species are artificially grouped in captivity, they develop a social hierarchy which in turn results in physiological disorders, especially of reproductive function, in non-dominant individuals. Since olfactory behaviours appear to be important in the establishment and maintenance of the social structure, we have tested the effects of dominant odorant signals upon the sexual inhibition observed in male conspecifics. A preliminary experiment showed that a decrease in plasma testosterone concentrations could be induced by dominant scent marks. Furthermore, dominant urine odour alone was found to be sufficient to induce this modification. Plasma cortisol levels also increased in these animals. Conversely, when sexually inhibited males were olfactorily isolated from dominant urine odour, testosterone and cortisol concentrations returned to a normal seasonal level. These effects were observed even in males which had had no previous contact with the dominant urine donor. It is inferred from these results that a pheromone-like process could lead to sexual inhibition in male Microcebus murinus exposed to an odorant urinary signal produced by a dominant individual. Nevertheless, the endocrine response seems to vary according to the seasonal period of the sexual activity cycle which suggests that the social effect described is modulated by other external (e.g. photoperiodic) or internal (e.g. reproductive physiology) factors.

J. Endocr. (1984) 102, 143–151
Inhibition by testosterone of prolactin and growth hormone release from chicken anterior pituitary glands in vitro
Authors: Hall T. R. , Harvey S. , Chadwick A.
Published: December 2008

Pituitary glands and hypothalami from broiler fowl were incubated in medium containing testosterone, and prolactin and GH release were determined. Pituitary glands were also preincubated for 20 h in medium containing testosterone, and then in medium containing various secretagogues.

Testosterone inhibited the release of prolactin directly from the pituitary gland in a concentration-related manner. The hypothalamus stimulated the release of prolactin, but by a lesser amount in the presence of testosterone. When pituitary glands were preincubated with testosterone, subsequent release of prolactin was inhibited, except with the highest concentration which stimulated prolactin release. Hypothalamic extract (HE) markedly stimulated prolactin release from control pituitary glands although testosterone-primed glands were less responsive. The stimulation of prolactin release by thyrotrophin releasing hormone (TRH) and prostaglandin E2 (PGE2) was also reduced by preincubation of the pituitary glands with testosterone.

Priming with testosterone did not affect the release of GH from pituitary glands alone, but reduced the TRH-, HE- and PGE2-stimulated release of GH. These results demonstrate that testosterone directly inhibits prolactin secretion and reduces the sensitivity of pituitary lactotrophs and somatotrophs to provocative stimuli.

J. Endocr. (1984) 102, 153–159
Effect of adrenalectomy and steroid treatment on rat skin cytosol glucocorticoid receptor
Authors: Smith K. , Shuster S.
Published: December 2008

Using an exchange assay to measure occupied and unoccupied binding sites, the glucocorticoid receptor in rat skin cytosol has been measured after adrenalectomy and parenteral steroid administration. Adrenalectomy increased the number of receptor sites with maximal effect after 5 days, after which numbers decreased to those of intact animals. Injection of adrenalectomized animals with the unlabelled agonist corticosterone resulted in a rapid dose-related decrease in the number of cytosolic receptor sites at 30 min whereas the antagonist progesterone had no effect. It is concluded that changes in glucocorticoid concentration lead to rapid inverse changes in cytosolic receptor.

J. Endocr. (1984) 102, 161–165
Seasonal differences in ovarian activity in cows
Authors: McNatty K. P. , Hudson N. , Gibb M. , Henderson K. M. , Lun S. , Heath D. , Montgomery G. W.
Published: December 2008

The plasma concentrations of LH and prolactin and various parameters of ovarian function were examined in cows on known days of the oestrous cycle during May and June (autumn and winter) and during October (spring).

Luteinizing hormone peak frequency and plasma prolactin concentrations were significantly higher in October than during the May–June period (LH, P<0·05; prolactin, P<0·01). The mean diameters of large healthy follicles (≥8 mm diameter) and the dominant oestrogen-secreting follicles were significantly larger (P<0·01 for both follicle types) and each follicle contained more granulosa cells (both P<0·01) in May–June than in October. The LH responsiveness of theca interna with respect to androstenedione production and the levels of aromatase activity in granulosa cells did not differ with time of year. The corpora lutea were heavier (P<0·05) and secreted more progesterone (P<0·01) in May–June than in October.

It is concluded that seasonal differences in ovarian activity exist in cows and that these differences are probably the consequence of seasonal differences in gonadotrophin secretion.

J. Endocr. (1984) 102, 189–198
Effects of pinealectomy, oestradiol and melatonin on plasma prolactin and LH secretion in ovariectomized sheep
Authors: Kennaway D. J. , Dunstan E. A. , Gilmore T. A. , Seamark R. F.
Published: December 2008

The study examines whether the pineal gland mediates in the seasonal rhythm in the response of the hypothalamo-pituitary axis to oestrogen in the sheep. Five groups of ewes, each comprised of five sham-pinealectomized ewes and five pinealectomized ewes, were maintained under field conditions over a 2-year period. Group 1 ewes were ovariectomized and treated with two oestradiol capsules in the first year and one oestradiol capsule in the second year; group 2 ewes were ovariectomized and treated with two oestradiol capsules and three melatonin sachets in the first year and one oestradiol capsule and three melatonin sachets in the second year; group 3 ewes were ovariectomized and treated with three melatonin sachets in the first year and one oestradiol capsule in the second year; group 4 ewes were ovariectomized and treated with empty implants; group 5 had intact ovaries. Blood samples were taken at weekly intervals for determination of plasma prolactin, LH and FSH levels. Cyclic ovarian activity, determined by rams fitted with a marking harness, occurred in both sham-pinealectomized and pinealectomized ewes in group 5 during December to May in both years. A circannual rhythm in plasma prolactin levels was apparent in all ten groups of animals. The levels were highest in spring (September to November) and decreased before the onset of breeding activity in midsummer (December). Ovariectomized ewes with intact pineal glands and treated with oestradiol capsules (group 1) exhibited marked changes in LH and FSH concentrations during the study. The highest plasma gonadotrophin levels were observed coincident with the breeding season in control ewes (group 5). Continuous melatonin administration together with oestradiol (group 2, sham-pinealectomized) resulted in higher levels of gonadotrophins but the loss of the seasonal rhythm. However, melatonin alone was not able to alter gonadotrophin levels in either sham-pinealectomized or pinealectomized ovariectomized ewes. Pinealectomized ovariectomized ewes treated with oestradiol alone did not show a seasonal change in LH or FSH; in fact these animals appeared to be more sensitive to the negative feedback actions of oestradiol. Combined melatonin/oestradiol administration resulted in an increase in gonadotrophin levels but did not restore seasonality. These results suggest that the pineal gland is the mediator of the seasonal rhythm in oestradiol feedback sensitivity. It is apparent that a seasonal change in breeding activity can occur in the absence of any change in oestradiol feedback sensitivity. The results of this study highlight the complex nature of photoperiod/environment interactions involved in seasonal breeding.

J. Endocr. (1984) 102, 199–207