bluuebunny/crossref_metadata_2025 huggingface dataset:
EFFECTS OF HYPOTHALAMIC DEAFFERENTATION ON BASAL AND STRESS-INDUCED ADRENOCORTICAL ACTIVITY IN THE PIGEON
Authors: BOUILLE C. , HERBUTÉ S. , BAYLÉ J. D.
Published: December 2008

Partial and complete deafferentation of the hypothalamus of the pigeon was performed using a modified Halasz-Pupp microknife. After complete neural isolation the plasma corticosterone level stabilized at a point intermediate between the morning and evening levels found in intact pigeons. No diurnal rhythm was observed and the response to neurogenic stimulus (restraint) was suppressed. Ether stress, however, induced a rise in plasma corticosterone. Posterior deafferentation had no effect on the diurnal corticosterone rhythm but did block the rise normally found after restraint. Anterior deafferentation did not suppress the stress-induced response but provided the cuts were large enough they inhibited the diurnal corticosterone rhythm.

It is suggested therefore that the neural afferents to the hypothalamus which are necessary for diurnal fluctuations in pituitary-adrenal function pass through a sector located anteriorly between 45° and 60° on either side of the mid-line while stress-induced adrenocortical activation is triggered through posterior connexions.
VASOTOCIN-LIKE ACTIVITY IN THE PLASMA OF THE EURYHALINE FROG (RANA CANCRIVORA) AFTER TRANSFER FROM FRESH WATER TO SALINE
Authors: ELLIOTT ANNIE B. , CHEW MIOW-MIOW
Published: December 2008

When Rana cancrivora were collected from fresh water and dehydrated (weight loss 4–10%) by exposure to saline, the plasma titre of hydro-osmotic activity, measured by amphibian bladder assay, was increased three- to fourfold. This activity, which was abolished by thioglycollate and by incubation with tyrosinase or trypsin, was ascribed to vasotocin. The plasma vasotocin activities (hydrated and dehydrated frogs respectively) were estimated to be 0·03–0·05 and 0·15–0·25 μg/1; if referred to oxytocin as a standard the equivalent values were 10 and 30–60 mu./ml. Assuming that the increase represented released pituitary hormone, the amount of vasotocin released by osmotic dehydration was calculated to be of the order of 1 ng.

Pituitary glands of hydrated and dehydrated frogs were estimated to have 0·15 and 0·18 μg vasotocin/gland respectively.

The possible physiological function of released vasotocin in promoting reabsorption of urea from the urinary bladder is discussed in relation to the euryhaline ability of R. cancrivora.
CHANGES IN INSULIN CONTENT OF, AND INSULIN AND RNA SYNTHESIS IN, ISOLATED RAT ISLETS OF LANGERHANS AFTER HYPOPHYSECTOMY AND SHORT-TERM GROWTH HORMONE REPLACEMENT
Authors: PARMAN A. Ü.
Published: December 2008

Three to four weeks after hypophysectomy, the insulin content and glucose-stimulated insulin or total RNA synthesis in the pancreatic islets were estimated. The ratio of the glucose-stimulated insulin release to the islet insulin content was lowered. After shortterm GH replacement, insulin release and insulin content were slightly increased such that the ratio of release to content remained virtually unaltered. Glucose-stimulated insulin synthesis was also depressed but improved slightly after GH replacement. However, there was no significant change in the incorporation of [5-3H]uridine into islet total RNA after hypophysectomy or subsequent GH replacement.
IDENTIFICATION OF HUMAN LUTEINIZING HORMONE, FOLLICLE-STIMULATING HORMONE, LUTEINIZING HORMONE β-SUBUNIT AND GONADOTROPHIN α-SUBUNIT IN FOETAL AND ADULT PITUITARY GLANDS
Authors: HAGEN C. , McNEILLY A. S.
Published: December 2008

Specific radioimmunoassays were used to assess the content of LH, FSH, the gonadotrophin α-subunit and the LH β-subunit in four adult, 19 normal foetal pituitary glands (9·5–32 weeks of gestation) and a pituitary extract from an anencephalic foetus (36 weeks). The hormones and subunits were further identified by column chromatography on Sephadex G-100. All pituitary glands contained free α-subunit and intact LH but the α-subunit:LH ratio was significantly higher in the early foetal pituitaries (9·5–16 weeks) than in the four adult pituitaries. Only small or undetectable amounts of LH β-subunit and 'undetectable' FSH were found in these early foetal pituitaries (9·5–11·5 weeks). The concentration of intact hormones or subunits in the pituitaries showed no significant sex difference in any of the groups. In contrast to these results, only α-subunit was detectable in the pituitary of the anencephalic foetus.

For 14 early foetuses (age of gestation 10–16 weeks) the serum levels of LH–HCG, FSH, and α-subunit in the circulation were significantly higher than in 26 foetuses at term (37–41 weeks). On the basis of these results a theory for the development of the gonadotrophin secretion from the foetal pituitary gland is outlined.
PLASMA PROGESTERONE LEVELS IN GUINEA-PIGS ACTIVELY IMMUNIZED AGAINST PROSTAGLANDIN F2α, HYSTERECTOMIZED OR TREATED WITH INTRA-UTERINE INDOMETHACIN
Authors: POYSER N. L. , HORTON E. W.
Published: December 2008

Five guinea-pigs actively immunized against a prostaglandin F2α(PGF2α)–bovine serum albumin conjugate showed elongated oestrous cycles. During these, corpora lutea were maintained in a functional secretory state as indicated by plasma progesterone levels. The results are compatible with the view that the PGF2α antibodies neutralized the PGF2α released from the uterus and thus prevented its normal luteolytic effect. Similar patterns of progesterone secretion were observed in two hysterectomized animals and in two animals with intra-uterine implants of indomethacin.
EFFECT OF MAGNESIUM DEFICIENCY AND PARATHYROID HORMONE ON CYCLIC AMP METABOLISM IN RAT RENAL CORTEX
Authors: ASHBY J. P. , HEATON F. W.
Published: December 2008

The influence of magnesium deficiency on cyclic AMP metabolism was investigated in rats on diets of normal and low calcium content. Magnesium deficiency itself did not significantly affect either the basal concentration or the parathyroid hormone-stimulated formation of cyclic AMP in the renal cortex.

Magnesium-deficient rats with hypercalcaemia excreted more cyclic AMP in the urine, but similar rats that developed hypocalcaemia on low calcium intake excreted less than their respective controls. The former type of animals also tended to accumulate more cyclic AMP in the renal cortex in response to the injection of a standard dose of parathyroid hormone, whereas rats of the latter type accumulated less. The activity of parathyroid hormone-stimulated renal cortical adenylate cyclase in vitro was increased by magnesium and reduced by calcium under most conditions, but with low concentrations of magnesium small amounts of calcium had a stimulatory effect. These observations suggest that cyclic AMP metabolism is influenced by metabolic disorders developing secondary to magnesium deficiency.
ELECTRICAL STIMULATION OF THE HYPOTHALAMUS AND LUTEINIZING HORMONE SECRETION IN JAPANESE QUAIL
Authors: DAVIES D. T. , FOLLETT B. K.
Published: December 2008

Experiments were undertaken to localize those hypothalamic areas in the male quail (Coturnix coturnix japonica) where electrical stimulation would increase LH secretion. The posterior basal hypothalamus was stimulated with rectangular pulses (height 500 μA) through a bipolar electrode for 6 min, blood samples being taken for LH assay 20 min before, and 2, 10, 20 and 30 min after stimulation. The highest plasma concentration was observed in the 2 min sample. Over the next 30 min the LH level decreased to the resting concentration. The relative increase in LH level was greatest in sexually immature quail and least in photostimulated castrated birds, although the highest absolute levels were seen in the castrated quail. There were no statistical differences between the magnitude of the LH increases in sexually immature, mature and castrated quail.

Various hypothalamic regions were then stimulated with a smaller current (200 μA) applied for only 2 min. A highly significant rise in LH followed stimulation of either the tuberal hypothalamus (postero-dorsal part of the infundibular nuclear complex, PD-INC), or the preoptic region (POR) while stimulation 0·5–1·5 mm away from these regions did not change LH secretion. Stimulation of the anterior basal hypothalamus, or of the suprachiasmatic area, caused a significant rise in LH concentration although this was less than that seen after stimulation of the POR. Stimulation in the POR or the PD-INC was ineffective if the tuberal hypothalamus had been deafferentated surgically some days previously. The data complement the studies in which destruction of the PD-INC or the POR by electrolytic lesions has been shown to block photoperiodically induced testicular growth and LH secretion.
POTENTIATION BY URETHANE AND INHIBITION BY PENTOBARBITONE OF OXYTOCIN RELEASE IN VITRO
Authors: DYBALL R. E. J.
Published: December 2008

Isolated rat neural lobes were incubated in vitro in Locke's solution containing anaesthetic quantities of urethane, pentobarbitone or tribromoethanol. The oxytocin content of the incubation medium was estimated before, during and after stimulation of the tissue by raising the potassium chloride concentration from 5·6 to 56 mmol/l. Urethane (25 mmol/l) significantly potentiated oxytocin release (P < 0·01) whereas tribromoethanol (0·5 mmol/l) had no obvious effect and pentobarbitone (0·4 mmol/l) significantly (P < 0·01) inhibited its release. Reduction of the sodium chloride concentration in the medium potentiated the release of oxytocin in each case but did not alter its pattern. Urethane which increased secretion of oxytocin also increased calcium ion uptake by the neural lobes and pentobarbitone which decreased oxytocin release decreased calcium ion uptake. The results may explain why the blood concentration of the neurohypophysial hormones tends to be higher in rats anaesthetized with urethane than with tribromoethanol. Inhibition of hormone release by pentobarbitone suggests that this anaesthetic is unsuitable for use in studies of neurohypophysial hormone release. A partial explanation of the anaesthetic properties of urethane and pentobarbitone may also have been found if the release of neurotransmitter substances is influenced in a similar manner.
STIMULATION OF CARP INTERRENAL FUNCTION BY ADRENOCORTICOTROPHIN
Authors: ILAN Z. , YARON Z.
Published: December 2008

The effect of ACTH on cortisol concentration in the plasma of the carp has been studied; cortisol was determined using a competitive protein-binding radioassay. Blood was sampled at 12.00 h (the diurnal minimum) by cardiac puncture. The plasma cortisol level of undisturbed carp (blood obtained 1–3 min after netting) was 46 ± 14 (s.e.m.) ng/ml.

One hour after injection of ACTH (1·0 i.u./100 g body wt., i.m.) the level of cortisol increased to 415 ± 62 ng/ml and reached a maximum of 656 ± 62 ng/ml after 2 h. The level of cortisol in saline-injected control carp after 2 h was 72 ± 33 ng/ml. A transient rise of cortisol was noted in both groups 30 min after injection (315 ± 51, 315 ± 62 ng/ml). This was attributed to a surge of endogenous ACTH, presumably due to handling.

Carp head kidneys were superfused in vitro. They released cortisol spontaneously, but the releasing rate declined exponentially and reached a minimum after 135 min. Addition of ACTH to the medium was followed by a prompt increase in cortisol release. The rate of cortisol release was maximal 30–45 min after addition of ACTH and was identical to the rate at the beginning of the superfusion.
INABILITY OF ACTINOMYCIN D TO ACT UPON THE UTERINE REFRACTORY STATE RESULTING FROM NIDATORY OESTROGEN ACTION IN RATS
Authors: LEROY F. , VAN HOECK J. , BOGAERT C.
Published: December 2008

After priming with oestradiol, ovariectomized rats were given 6 days of progesterone treatment in which two doses of 50 ng oestradiol were superimposed on days 3 and 6. This basic regimen allows the oestradiol-induced (1st injection) inhibition of uterine sensitivity to decidual stimuli to appear. Actinomycin D given instead of, or together with, the first dose of oestradiol could not mimic, or prevent oestrogen action in the occurrence of the uterine refractory state. This drug was unable to interfere with the minimal 48 h progesterone treatment which is requisite to uterine sensitization. Our results together with other data from the literature, suggest that luteal hormones do not need to act at the transcriptional level to sensitize and desensitize the uterus to implantation.
PLACENTAL LACTOGEN IN THE COW
Authors: BUTTLE H. L. , FORSYTH ISABEL A.
Published: December 2008

Placental lactogen secretion has been demonstrated in cows on days 36, 178, 182 and 270 of pregnancy by co-culture of cotyledonary tissue with mouse mammary gland explants. Bovine placental lactogen probably originated from the foetal cotyledon and showed no detectable cross-reaction in immunoassays for bovine prolactin or growth hormone. Peripheral plasma samples collected from seven primiparous heifers at 2-week intervals throughout pregnancy showed a seasonal rhythm in prolactin concentration, measured by radioimmunoassay, with high levels in the summer. Monthly samples were bioassayed for total lactogenic activity by a rabbit mammary gland organ culture method. Positive responses were obtained only when prolactin levels were high ( > 70 ng/ml), indicating that levels of placental lactogen in the circulation are much lower in the cow than in sheep, goats or women.
THE INFLUENCE OF OESTRADIOL-17β AND PROGESTERONE ON THE CONTRACTILITY OF THE OVIDUCT OF THE TURTLE, CHRYSEMYS PICTA, IN VITRO
Authors: CALLARD I. P. , HIRSCH MADELYN
Published: December 2008

The contractility of the oviduct of Chrysemys picta (the fresh-water turtle) was studied in vitro. Significant regional differences in contractile activity were observed. Contractions increased in amplitude and duration and decreased in frequency from the proximal to the distal end of the oviduct. Injections of oestradiol-17β in vivo increased the amplitude of contractions and decreased the duration of the rest period in segments taken from the distal end of the oviduct. In contrast, progesterone injections significantly reduced the duration of both contractile and resting periods.
EFFECT OF UNILATERAL AND BILATERAL CASTRATION AND CRYPTORCHIDISM ON SERUM GONADOTROPHINS IN THE RAT
Authors: GOMES W. R. , JAIN S. K.
Published: December 2008

The effects of unilateral and bilateral cryptorchidism and castration on serum concentrations of testosterone, FSH and LH in adult male rats were examined. The results provide no evidence for compensatory growth or development of the remaining scrotal testes up to 32 days after unilateral castration, although the scrotal testis of unilaterally cryptorchid rats showed enlargement when compared with those of control rats (P < 0·05) at 32 days. Unilateral treatments had few significant effects on serum hormones, but testosterone was increased on day 4 (P < 0·05) in unilaterally cryptorchid rats and on day 32 (P < 0·05) in unilaterally castrated rats, compared with controls, and FSH levels were higher in unilaterally castrated rats on day 16 (P < 0·05). Bilateral cryptorchidism caused an increase in serum FSH within 4 days (P < 0·05) and in serum LH by 8 days (P < 0·05) after surgery, with both hormones reaching levels double those found in control rats (P < 0·01) by day 16, while testosterone levels were maintained at or above control values. Bilateral castration resulted in a marked decrease in testosterone levels (P < 0·01) and a sharp increase in serum gonadotrophins. FSH had nearly doubled (P < 0·01) and LH had increased fourfold (P < 0·01) 4 days after castration, their levels reaching 773% (LH) and 287% (FSH) of control values by 32 days (P < 0·01). The observations support the hypothesis of a separate, testosterone-independent feedback system of the testis on the hypophysis.
HORMONE STORAGE IN INDIVIDUAL NEUROSECRETORY GRANULES OF THE PITUITARY GLAND: A QUANTITATIVE ULTRASTRUCTURAL APPROACH TO HORMONE STORAGE IN THE NEURAL LOBE
Authors: MORRIS J. F.
Published: December 2008

A quantitative ultrastructural study of the neurosecretory granules in the neural lobe of the rat was performed in order to calculate the number of such granules in the neural lobe and thus, provided all hormone is intragranular, to derive the hormone content of individual granules. The results suggest that the gland contains 1·44 × 1010 granules and that an individual granule (mean diameter 160 nm) contains about 84000 hormone molecules. The errors involved in the many measurements made are analysed, and the calculated value for the amount of space available for each hormone molecule within the granule is shown to agree well with independently reported data for the expected size of a molecule of protein–hormone complex, and for the size of subunits visualized in freeze-etched material.

These results are compatible with exclusive intragranular hormone storage as a 'solid' core, and the physical form that this core might take is discussed. The data are used to express what is known of hormone turnover and release in terms of the numbers of granules involved. Comparison of different parts of the neural lobe suggests that, apart from the most anterior part of the gland, there is little regional variation in quantitative aspects of granule storage in the neural lobe.
RELATION BETWEEN PROLACTIN AND GONADOTROPHIN SECRETION IN POST-PARTUM LACTATING RATS
Authors: LU K. H. , CHEN H. T. , HUANG H. H. , GRANDISON L. , MARSHALL S. , MEITES J.
Published: December 2008

In post-partum lactating rats, sucking by the young was associated with high prolactin release and maintenance of lactation but severe inhibition of LH and FSH release and suspension of oestrous cycles. Shortly after the pups were removed on day 22 post partum, LH and FSH release returned to normal and oestrous cycles resumed. Twice-daily injections of ergocornine methanesulphonate (ERG) into mothers beginning at 5 or 7 days post partum, resulted in sustained inhibition of prolactin release and diminished milk secretion. By frequent exchange of pups between control and ERG-treated mothers, it was possible to maintain vigorous sucking and almost normal pup growth despite low serum prolactin levels and diminished lactation. In these rats, serum levels of LH remained low during 11 or more days of treatment with ERG, but serum FSH was consistently higher than in untreated control mothers. After 11 or more days of ERG treatment, most rats showed a return to normal LH and FSH release and resumption of oestrous cycles. These results suggest (a) that the sucking stimulus rather than high prolactin levels in the circulation is mainly responsible for inhibition of LH and FSH release during the first 11 days post partum, (b) that the sucking stimulus acts to increase prolactin and inhibit LH release by separate hypothalamic mechanisms, and (c) that administration of ERG results in diminished prolactin release and lactation, and in increased release of FSH and subsequently of LH with earlier resumption of oestrous cycles.
DEVELOPMENTAL, DIURNAL AND OESTROUS CYCLE-DEPENDENT CHANGES IN THE ACTIVITY OF LIVER ENZYMES
Authors: STENBERG ÅKE
Published: December 2008

The metabolism of [4-14C]4-androstene-3,17-dione was studied in the 105000 g microsomal and supernatant fractions of liver from developing rats of both sexes. The following enzyme activities were measured: 5β-reductase (supernatant fraction) and 5α-reductase, 17α- and 17β-hydroxysteroid reductases, 6β-, 7α- and 16α-hydroxylases (microsomal fraction). The activities of the 3α- and 3β-hydroxysteroid reductases were estimated by calculating the ratios of 3α-:5α- and 3β-: 5α-reduced metabolites formed, respectively.

Most enzyme activities present at birth (i.e. 5β-reductase, 5α-reductase, 17β-hydroxysteroid reductase, 6β- and 7α-hydroxylase) increased until 20 days of age in both male and female rats. Between 20 and 30 days of age a number of masculine metabolic characteristics appeared in both sexes, i.e. the 16α-hydroxylase and the 17α-hydroxysteroid reductase were induced, the 5β-reductase activity rapidly increased and the 5α-reductase activity slightly decreased. During a third period beginning 30 days after birth the adult male enzyme activity pattern was completed by the induction of 3β-hydroxysteroid reductase and a further increase in the activity of 16α-hydroxylase. After 30 days of age a feminine type of liver metabolism also rapidly developed in female rats; the 16α-hydroxylase and the 17α-hydroxysteroid reductase activities disappeared, the 6β-hydroxylase and the 5β-reductase activities decreased and the 5α-reductase activity increased six times.

The developmental patterns of enzyme activities in the rat liver are consistent with a first developmental phase (0–30 days of age) independent of hypophysial control and probably determined primarily by the genome of the liver cell and a second phase (from 30 days onwards) with increasing sexual differentiation under hypophysial control. This control is mediated by some kind of feminizing factor in female rats and possibly by some kind of androgen-elicited secretion of masculinizing factor(s) in male rats.

The metabolism of [4-14C]4-androstene-3,17-dione was also studied during different times of the day and during different phases of the oestrous cycle. The 16α-hydroxylase activity showed a diurnal variation with higher values at noon than at midnight. The 5β-reductase activity reached a maximal activity during metoestrus.
INHIBITION OF HUMAN CHORIONIC GONADOTROPHIN-INDUCED HYPERTROPHY OF THE OVARIES AND UTERUS IN IMMATURE MICE BY SOME PINEAL INDOLES, 6-HYDROXYMELATONIN AND ARGININE VASOTOCIN
Authors: VAUGHAN MARY K. , VAUGHAN G. M. , REITER R. J.
Published: December 2008

Administration of the indoles 5-methoxytryptophol, 6-hydroxymelatonin, melatonin, N-acetylserotonin or 5-methoxyindole-3-acetic acid (six 100-μg injections given at intervals of 12 h) inhibited both the absolute and relative ovarian and uterine weights of immature female mice pre-treated with HCG. Administration of 5-hydroxytryptophol or 5-methoxytryptamine at the same dosage inhibited ovarian but not uterine hypertrophy in mice pre-treated with HCG.
EFFECTS OF SODIUM PENTOBARBITONE ADMINISTRATION ON GONADOTROPHIN RELEASE, FIRST OVULATION AND OVARIAN MORPHOLOGY IN PUBERTAL RATS
Authors: OSMAN P. , MEIJS-ROELOFS H. M. A.
Published: December 2008

Pubertal female rats received sodium pentobarbitone (PB; 45 mg/kg body wt) at various hours on the day of first pro-oestrus. Maximal blockade of ovulation, in about 60% of the rats, occurred after PB treatment at 12.00, 13.00 and 14.00 h. The number of small antral follicles (100–499 × 105 μm3) was reduced 1 day after PB treatment in both blocked and ovulating rats. In the ovaries of non-ovulating rats signs of stimulation by LH such as dispersion of cumulus cells, oocyte maturation and early luteinization were sometimes present; in ovulating rats cystic corpora lutea with entrapped ova were found in addition to normal corpora lutea. Gonadotrophin measurements after PB treatment (14.00 h) in pubertal and adult rats showed (at 17.00 h) reduced levels of both LH and FSH, these levels being lower in the adults. Gonadotrophin levels of blocked and ovulating pubertal rats overlapped.

In PB-treated, pubertal rats in which ovulation was postponed by 1 day, vaginal oestrus was prolonged by 1 day and the subsequent dioestrus by 2 days.

The pubertal rat is thus less sensitive to PB treatment than the adult. PB treatment of the younger animal influences not only the ovulatory process but also follicular growth and, presumably, the length of the approaching cycle.
EFFECT OF VARIOUS PUTATIVE NEUROTRANSMITTERS ON THE SECRETION OF CORTICOTROPHIN-RELEASING HORMONE FROM THE RAT HYPOTHALAMUS IN VITRO – A MODEL OF THE NEUROTRANSMITTERS INVOLVED
Authors: JONES M. T. , HILLHOUSE E. W. , BURDEN JANET
Published: December 2008

The effect of incubating the hypothalamus of adult male rats with various neurotransmitters upon the release of corticotrophin-releasing hormone (CRH) was studied. The CRH activity in the incubation medium was assayed in 48 h median eminence-lesioned rats and the corticosteroidogenesis of excised adrenals in vitro was used as the end-point. 5-Hydroxytryptamine (100 pg/ml–10 ng/ml) caused a dose-dependent release of CRH which was antagonized by methysergide (30–100 ng/ml). The response to 5-hydroxytryptamine was also inhibited by hexamethonium and atropine which indicated that it was acting through a cholinergic interneurone. Melatonin (10 ng) did not alter the basal release of CRH but inhibited the action of both 5-hydroxytryptamine (10 ng) and acetylcholine (3 pg). Thus it appears that both 5-hydroxytryptamine and melatonin play a role in the control of CRH release. Noradrenaline blocked the release of CRH induced by both acetylcholine and 5-hydroxytryptamine and presumably this inhibition was caused by direct action on the CRH neurone. γ-Aminobutyric acid (GABA) also inhibited the release of CRH and may also be involved in the regulation of CRH secretion. The inhibitory neurotransmitters, noradrenaline, GABA and melatonin, act via independent receptor mechanisms. A model based on the above data is presented.
EFFECT OF IONIC ENVIRONMENT ON THE RELEASE OF HUMAN PLACENTAL LACTOGEN IN VITRO
Authors: CHOY V. J. , WATKINS W. B.
Published: December 2008

Short-term incubation of human placental tissue in Krebs–Ringer bicarbonate buffered media with various concentrations of K+ and Ca2+ showed a graded response in human placental lactogen (HPL) release at different Ca2+ concentrations, but no effect at increased K+ concentration. Media with high Ca2+ caused an inhibition of release, while Ca2+-free media caused a stimulation in HPL release. High concentrations of Mg2+ inhibited release minimally, while Ba2+ had no effect. There was no change in HPL release when Na+ concentration was increased. La3+-Locke's solution markedly inhibited release of HPL but the significance of this effect is unknown. These results suggest that Ca2+ is not required for HPL secretion from placental tissue. It seems that HPL secretion in vitro does not follow the usual pattern where a physiological stimulus or high K+ concentration causes inward movement of calcium which couples stimulation to secretion.
PRIMING EFFECT OF LUTEINIZING HORMONE RELEASING FACTOR ELICITED BY PREOPTIC STIMULATION AND BY INTRAVENOUS INFUSION AND MULTIPLE INJECTIONS OF THE SYNTHETIC DECAPEPTIDE
Authors: FINK G. , CHIAPPA S. A. , AIYER M. S.
Published: December 2008

We have investigated whether the priming effect of LH-RF can be elicited by electrical stimulation of the medial preoptic area, or by i.v. infusion or multiple i.v. injections of the synthetic decapeptide. All experiments were carried out on animals anaesthetized with sodium pentobarbitone at 13.30 h. In pro-oestrous rats, the LH response to the second of two electrical stimuli, 15 min in duration and separated by 60 min, was significantly greater than the response to the first stimulus. When synthetic LH-RF was infused at a constant rate for 90 min, plasma LH increased gradually for the first 45–60 min after which it increased markedly. This enhanced secretion of LH did not occur in rats which were infused with the same total dose of LH-RF, either 15 or 75 ng/100 g body wt, over periods of 45 min or less. When a dose of 15 ng LH-RF/100 g body wt was administered in six divided doses by i.v. injections, each separated by 15 min, there was a marked increase in plasma LH after 75 min. The profile of the mean plasma LH concentration in rats subjected to preoptic stimulation for 90 min was similar to that in rats infused for 90 min with LH-RF, but the variation in response was much greater in the stimulated rats.

These results indicate that the priming effect can be elicited by endogenous as well as synthetic LH-RF, and that whether LH-RF reaches the pituitary at a constant rate or in a pulsatile manner the factor is capable of significantly increasing the responsiveness of the gonadotrophs. The relevance of these findings with respect to the development of the spontaneous preovulatory LH surge is discussed. A priming effect could not be elicited by constant LH-RF infusion in dioestrous rats; this supports the view that steroid hormones, especially oestradiol-17β, determine the magnitude of the effect. The LH response in male rats subjected to i.v. infusion of LH-RF was much lower than in females. Pre-treatment with oestradiol benzoate did not increase the response significantly, suggesting that this sex difference cannot be ascribed simply to low levels of plasma oestrogen in the male.
EFFECT OF GUANYL NUCLEOTIDES ON PARATHYROID HORMONE-RESPONSIVE ADENYLATE CYCLASE IN CHICK KIDNEY
Authors: HUNT N. H. , MARTIN T. J. , MICHELANGELI V. P. , EISMAN J. A.
Published: December 2008

Both guanosine 5′-triphosphate (GTP) and 5′-guanylylimidodiphosphate (Gpp(NH)p) activated adenylate cyclase (EC 4.6.1.1) in chick kidney plasma membranes. Half-maximal stimulation occurred at 3·1 × 10−6 m for both agents. The maximum increases in adenylate cyclase activity produced by GTP and Gpp(NH)p were respectively 130 and 720% over basal activity.

At the end of a 12 min incubation period GTP concentration was 85% of that originally added in the presence of an ATP-regenerating system but less than 20% in its absence.

GTP and guanosine 5′-diphosphate inhibited the activation of adenylate cyclase by Gpp(NH)p, suggesting that they all acted at a common site. Gpp(NH)p facilitated the stimulation of adenylate cyclase activity by bovine parathyroid hormone (BPTH) and by the synthetic amino terminal fragment BPTH (1–34), decreasing the concentrations required for half-maximal enzyme activation by a factor of approximately eight in both cases. This property was not shared by the native nucleotide GTP. Gpp(NH)p rendered active (at certain concentrations) a synthetic parathyroid hormone peptide fragment, BPTH (2–34), which was incapable of activating adenylate cyclase in the absence of the nucleotide analogue. This suggested that the GTP analogue, in addition to a direct effect upon adenylate cyclase activity, was capable of influencing hormone interaction with the enzyme complex.
ROLE OF THE THYROID GLAND IN REGULATION OF METABOLIC RATE IN AN AIR-BREATHING SILUROID FISH, HETEROPNEUSTES FOSSILIS (BLOCH)
Authors: PANDEY B. N. , MUNSHI J. S. D.
Published: December 2008

Studies on cyclic activity of the thyroid and seasonal variations in oxygen consumption (V̇o2) under experimental conditions in which surfacing was either allowed or prevented were made in H. fossilis to try to establish a relationship between these measures and to ascertain the possible role of the thyroid in the regulation of metabolic rate. A good correlation was found between the activity of the thyroid and V̇o2 in this species. This finding was further confirmed by the administration of l-thyroxine or thiouracil to this fish. The thyroxine-and thiouracil-treated animals showed significantly higher (P < 0·05) and lower (P < 0·01) rates of V̇o2 respectively, thus indicating the probable role of the thyroid in the regulation of metabolic rate.
SUPPRESSION OF LUTEINIZING HORMONE RELEASE BY 5α-ANDROSTANE-3α,17β-DIOL AND ITS 3β EPIMER IN IMMATURE OVARIECTOMIZED RATS
Authors: ECKSTEIN B. , YEHUD S. , SHANI J. , GOLDHABER G.
Published: December 2008

The effect of 5α-androstane-3α,17β-diol, its 3β epimer and oestradiol benzoate on suppression of LH release after ovariectomy was studied in immature rats. At doses of 50 and 100 μg/100 g body weight/day the 3α compound suppressed LH release after ovariectomy to the same extent as 0·1 μg oestradiol benzoate/100 g/day. 3α-Androstanediol at a dose of 25 μg/100 g/day suppressed LH release only up to day 45 of life, while the same dose of the 3β epimer had no effect on LH suppression. The effect of 3β-androstanediol on inducing precocious vaginal opening was found to be mediated by the ovaries, since it was eliminated by ovariectomy. These results confirm our previous findings on the participation of androstanediol in the normal regulation of LH and in the mechanism of onset of puberty in the rat.
DEVELOPMENT AND APPLICATION OF A HETEROLOGOUS RADIOIMMUNOASSAY FOR OVINE FOLLICLE-STIMULATING HORMONE
Authors: McNEILLY JUDITH R. , McNEILLY A. S. , WALTON J. S. , CUNNINGHAM F. J.
Published: December 2008

A highly specific and sensitive heterologous double antibody radioimmunoassay for ovine follicle-stimulating hormone (oFSH) is described in detail. The assay using a rabbit antiserum to human FSH and either 125I-labelled rat FSH or 125I-labelled oFSH as tracer is specific for FSH. A maximum cross-reaction (B/Bo = 50%) of 0·1% was observed with other ovine, rat or human pituitary hormones or human chorionic gonadotrophin. Serum levels of oFSH in samples collected daily throughout the oestrous cycle showed large individual variations. In five out of nine animals a peak of FSH was observed on the day of oestrus.
CHANGES IN ADRENOCORTICAL FUNCTION IN MALE AND FEMALE GUINEA-PIGS DURING MATURATION
Authors: GREINER J. W. , KRAMER R. E. , COLBY H. D.
Published: December 2008

Adrenal cortisol secretion is greater in female than male guinea-pigs and declines with maturation in animals of both sexes. In an attempt to determine the intra-adrenal mechanisms responsible for age and sex influences on corticosteroid output, adrenocortical enzyme activities were compared in sexually immature (3 weeks) and mature (17 weeks) animals. Adrenal mitochondrial protein concentration decreased with maturation in male and female guinea-pigs. 11β-Hydroxylase activity in adrenal mitochondria was also lower in mature than immature guinea-pigs but greater in males than females. Neither mitochondrial cytochrome P-450 concentration nor cholesterol side-chain cleavage activity varied with age or sex. Adrenal microsomal protein concentration and 21-hydroxylase activity were similar in male and female guinea-pigs of the same age but far greater in mature than immature animals. Microsomal cytochrome P-450 concentration was unaffected by age or sex. Adrenal Δ4-steroid (cortisol) hydrogenase activity increased with maturation in both male and female guinea-pigs and was higher in males than females. These observations indicate that cortisol secretion, as modified by age and sex, correlates closely with adrenal steroid reductive but not oxidative metabolism, suggesting that changes in Δ4-hydrogenase activity are responsible, at least in part, for the decline in adrenal secretion during maturation in guinea-pigs.
ADSORPTION OF FREE STEROIDS WITH CHARCOAL-GELATIN DISKS IN RADIOIMMUNOASSAYS
Authors: SABA N.
Published: December 2008

The preparation of charcoal–gelatin disks and their use for removing free steroid in radioimmunoassays are described. Plasma concentrations of several steroids were determined using charcoal–gelatin disks or charcoal suspension and the results are compared. The advantages of using charcoal–gelatin disks are discussed.
EFFECTS OF FOLLICLE-STIMULATING HORMONE AND LUTEINIZING HORMONE ON OVARIAN CYCLIC AMP AND PROSTAGLANDIN E IN VIVO IN RATS TREATED WITH INDOMETHACIN
Authors: RIGLER G. L. , PEAKE G. T. , RATNER A.
Published: December 2008

The role of prostaglandins in both FSH- and LH-mediated increases in ovarian cyclic AMP was examined in rats in vivo. Dose-related increases in ovarian cyclic AMP levels were observed 10 min after intravenous injection of FSH or LH. No changes in ovarian prostaglandin E (PGE) content were detected after injection of either gonadotrophin at doses which substantially enhanced cyclic AMP accumulation. Prior treatment of rats with indomethacin produced a greater than 50% decrease in ovarian PGE levels, but did not prevent the FSH- or LH-induced rise in ovarian cyclic AMP concentration. These in vivo experiments do not support the concept that PGE plays a role as an obligatory mediator for the gonadotrophin-induced rise in ovarian cyclic AMP levels.
ADMINISTRATION OF ANTISERUM AGAINST OVINE FOLLICLE-STIMULATING HORMONE OR OVINE LUTEINIZING HORMONE AT PRO-OESTRUS IN THE RAT: EFFECTS ON FOLLICULAR DEVELOPMENT DURING THE ONCOMING CYCLE
Authors: WELSCHEN R. , DULLAART J.
Published: December 2008

Cyclic rats received at 13.00 h on the day of pro-oestrus a single i.v. injection of one of the following antiserum preparations: AOLH (raised in rabbits against NIH-LH-S17); AOFSH (raised against NIH-FSH-S9) or pAOFSH (AOFSH preincubated with 195 μg NIH-LH-S16/ml). Rats were killed at day 1, 3 or 5 after injection, and the ovaries prepared for histological study of the antral follicles.

After AOLH, ovulation and resumption of meiosis in oocytes in pre-ovulatory follicles were prevented but follicular development during the following cycle appeared undisturbed. After either AOFSH or pAOFSH, blockade of ovulation was never observed but the formation of antral follicles normally occurring between mid-pro-oestrus and mid-oestrus was postponed by about one day. The later development of antral follicles might reflect a supranormal compensatory secretion of endogenous gonadotrophin because the development does not occur in AOFSH- or pAOFSH-treated rats hypophysectomized 24 h after injection and subsequently treated with pregnant mare serum gonadotrophin in dosage approximating the amount of gonadotrophin secreted endogenously during dioestrus.

The results imply (1) that the pre-ovulatory surge of LH release is not essential for follicular development during the oncoming cycle whereas (2) a surge of FSH release is required for the formation of the new cohort of antral follicles that is normally seen at the start of a new cycle.
PURIFICATION AND CHARACTERIZATION OF LEYDIG CELLS FROM RAT TESTES
Authors: JANSZEN F. H. A. , COOKE B. A. , VAN DRIEL M. J. A. , VAN DER MOLEN H. J.
Published: December 2008

An LH-responsive Leydig cell preparation (containing 6 ± 2% Leydig cells) was obtained by collagenase treatment of rat testis. Centrifugation of this cell preparation through a 13% Ficoll solution for 10 min at 1500 g resulted in a four times purification of the Leydig cells, with a concomitant increase in steroidogenic activity. Addition of 0·2% albumin to the 13% Ficoll solution, adjusted to 280 mosmol/l, resulted in a further twofold purification of the Leydig cells paralleled by a twofold increase in steroidogenic activity. Centrifugation of these Ficoll-albumin-purified Leydig cells through a 6% dextran solution for 2 min at 100 g resulted in a further 1·7 times purification of the Leydig cells. A combination of the two centrifugation steps resulted in a 12·5 times purification of Leydig cells compared with the original crude cell suspension, while an increase in steroidogenic activity of 22·5 times was obtained. This final cell preparation contained 59 ± 17% Leydig cells (mean ± s.d., n = 6). The recovery of Leydig cells was 29%.

Collagenase treatment of testes deficient in spermatogenesis resulted in a cell preparation with the same steroidogenic activity as Ficoll-purified cells from normal testes. Centrifugation of these cells through a 13% Ficoll solution gave only a limited increase in the steroidogenic activity. Isopycnic centrifugation of the crude cell preparation on a discontinuous Ficoll metrizoate gradient resulted in two discrete peaks of Leydig cells, one peak at a density of 1·039–1·055 g/ml and one at a density of 1·068–1·088 g/ml. Both types of cells produced testosterone. In the presence of LH, cyclic AMP production in both types of Leydig cells increased, but testosterone production was only increased by LH in the 'denser' Leydig cells and not in the 'light' Leydig cells.

No difference in sensitivity to LH could be observed between the Leydig cell preparations of different purity. Using a 60 min pre-incubation period the highest testosterone response was obtained with 100–1000 ng LH/ml. The same maximum testosterone response was obtained with 10–100 ng LH/ml when the pre-incubation period was omitted.
EFFECT OF THE ANTI-OESTROGEN TAMOXIFEN ON PLASMA LEVELS OF LUTEINIZING HORMONE, FOLLICLE-STIMULATING HORMONE, PROLACTIN, OESTRADIOL AND PROGESTERONE IN NORMAL PRE-MENOPAUSAL WOMEN
Authors: GROOM G. V. , GRIFFITHS K.
Published: December 2008

Plasma levels of LH, FSH, prolactin, oestradiol and progesterone were determined daily during two consecutive menstrual cycles in six women volunteers. During the first (control) cycle no treatment was given and normal secretion of these hormones was observed. Oral administration of tamoxifen (20 mg/day), for either 5 or 10 days of the follicular phase of the second cycle, caused no change in either the overall length of the cycle or the time of occurrence of the mid-cycle gonadotrophin surge. There was little difference in the secretion of LH, FSH and progesterone during the control and test cycles.

A two- to eight-fold increase in oestradiol levels was observed during the test cycle which was most pronounced at the times of mid-cycle and mid-luteal hormone peaks. There was a significant decrease in plasma prolactin levels at mid-cycle but no real difference could be seen during the remainder of the cycle.

The data suggest that tamoxifen may act directly on the ovary to stimulate oestradiol release without intermediary gonadotrophin stimulation. As the drug apparently inhibited prolactin secretion even in the presence of high oestradiol levels, an alternative explanation may be that the reduced prolactin concentration permits augmented ovarian stimulation by normal concentrations of gonadotrophins.
EFFECT OF THYROID STATUS ON THE THYROTROPHIN-RELEASING HORMONE-DEGRADING ACTIVITY OF RAT SERUM
Authors: WHITE N. , JEFFCOATE S. L. , GRIFFITHS E. C. , HOOPER K. C.
Published: December 2008

The TRH-degrading activity of rat serum in vitro is five times more potent than that of human serum. In rats, it is significantly reduced in hypothyroidism (thiouracil-induced) and significantly increased in hyperthyroidism (T3 or T4-induced). This suggests a possible role in the regulation of adenohypophysial-thyroid function which is probably, in turn, dependent on thyroid hormone, rather than TSH, levels.
ANDROGEN LEVELS IN THE PLASMA AND PROSTATIC TISSUES OF PATIENTS WITH BENIGN HYPERTROPHY AND CARCINOMA OF THE PROSTATE
Authors: HABIB F. K. , LEE I. R. , STITCH S. R. , SMITH P. H.
Published: December 2008

Specific radioimmunoassays for testosterone, dihydrotestosterone (DHT) and androstenedione were carried out to measure the concentrations of the three hormones in the plasma and prostatic tissue of ten patients with benign prostatic hypertrophy (BPH) and ten patients with carcinoma of the prostate.

The results indicate that there are no significant differences between the peripheral plasma concentrations of testosterone, DHT and androstenedione in BPH [19·7 ± 2·6, 2·6 ± 0·9 and 5·5 ± 1·7 (s.e.m.) nmol/l respectively] and in carcinoma 16·9 ± 2·8, 2·4 ± 0·5, 4·4 ± 1·1 nmol/l respectively], (in all cases P > 0·1). In contrast, the prostate tissue ratios DHT: testosterone (3·59 ± 0·55 for BPH and 0·66 ± 0·09 for carcinoma) and androstenedione: testosterone (2·83 ± 0·38 for BPH and 1·07 ± 0·16 for carcinoma) are significantly less in carcinoma than in benign hypertrophy (in all cases P < 0·01).

The accumulation of testosterone in the carcinoma, relative to values found in BPH tissue is, therefore, not associated with changes in the concentrations of androgens in the plasma pool but may be related to local factors and metabolic changes within the prostate.
GLYCEROL RELEASE IN VITRO FROM ADIPOSE TISSUE OF OBESE (ob/ob) MICE TREATED WITH THYROID HORMONES
Authors: OTTO W. , TAYLOR T. G. , YORK D. A.
Published: December 2008

Glycerol release from adipose tissue of adult genetically obese (ob/ob) mice was greater than that from adipose tissue of lean litter-mates. However, a higher concentration of adrenaline was required to stimulate lipolysis in ob/ob adipose tissue. Since oxygen consumption and the uptake of radioactive iodine by the thyroid were reduced and the biological half-life of thyroidal radio-iodine was lengthened, it is suggested that ob/ob mice are hypothyroid. The poor sensitivity of ob/ob adipose tissue to low doses of adrenaline was improved by treatment with either tri-iodothyronine or thyroxine. The lipolytic responses to both dibutyryl 3′:5′-cyclic adenosine monophosphate and aminophylline were enhanced in thyroid hormone-treated lean and ob/ob mice. A higher dose of tri-iodothyronine was required to enhance lipolysis in ob/ob mice than in lean controls. The possibility that hypothyroidism is responsible for the change in response of ob/ob adipose tissue to lipolytic hormones is discussed.
ANDROSTANEDIOL SULPHATES IN PERIPHERAL BLOOD OF IMMATURE RATS AND SOME OF THEIR BIOLOGICAL EFFECTS
Authors: RAVID RIVKA , ECKSTEIN BENJAMIN
Published: December 2008

The conjugation of 5α-androstane-3α,17β-diol (3α-A) and its 3β epimer (3β-A) was determined in the peripheral blood of immature female rats. About two thirds of these steroids were present in blood as sulphates and one third as glucuronides; no free steroids were detected. Administration of 3β-A sulphate (25 μg/100 g body weight/day) and of 3α-A sulphate (50 μg/100 g/day) from day 21 of life until the day of vaginal opening, advanced the day of the first ovulation. Administration of the 3β-A sulphate did not induce precocious vaginal opening whereas the free alcohol was active in this respect. Implantation of 3β-A sulphate, but not of the 3α epimer, into the basal medial hypothalamus resulted in the death of all animals within 24 h.
VASOPRESSIN RELEASE DURING VENTRICULO-CISTERNAL PERFUSION WITH PROSTAGLANDIN E2 IN THE DOG
Authors: YAMAMOTO MANABU , SHARE L. , SHADE R. E.
Published: December 2008

In an attempt to determine whether prostaglandin E2 (PGE2) can act centrally to affect the release of vasopressin (ADH), the ventriculo-cisternal system of anaesthetized dogs was perfused with PGE2. When PGE2 was perfused at a rate of 76·4 ng/min (0·19 ml/min), the plasma ADH concentration was unchanged. However, perfusion of PGE2 at a rate of 152·8 ng/min (0·19 ml/min) resulted in a significant increase in the plasma ADH concentration from the control value of 9·0 ± 2·2 (s.e.m.) to 18·8 ± 3·9 μu./ml at 10 min and to 41·0 ± 16·7 μu./ml at 30 min after the start of the perfusion. There were no changes in arterial blood pressure, rectal temperature, plasma osmolality, and the plasma concentrations of sodium and potassium. In additional experiments, i.v. injection of indomethacin (2 or 20 mg/kg) decreased the plasma ADH concentration by approximately 50%. Although this finding is consistent with a role of PGE2 in the control of ADH release, it could also have been due to the observed increases in arterial blood pressure and effective left atrial pressure. Plasma renin activity was unchanged in the indomethacin experiments. It is concluded that PGE2 can act in the central nervous system to stimulate ADH release.
PLASMA CONCENTRATION OF ANDROSTENEDIONE DURING THE BOVINE OESTROUS CYCLE
Authors: KANCHEV L. N. , DOBSON HILARY
Published: December 2008

A radioimmunoassay with Sephadex chromatography for androstenedione is described. Concentrations of androstenedione in bovine peripheral blood during the oestrous cycle ranged from 80 to 100 pg/ml. There was considerable variation and no pattern suggestive of physiological significance emerged, unlike those of oestradiol and testosterone.