bluuebunny/crossref_metadata_2025 huggingface dataset:
PROLACTIN, DIURETICS AND URINARY ELECTROLYTES IN NORMAL SUBJECTS
Authors: AUTY R. , BRANCH R. A. , COLE E. N. , LEVINE D. , RAMSAY L.
Published: December 2008

The relationship of plasma prolactin concentration and renal electrolyte excretion has been investigated in six normal male volunteers. In two studies, 80 mg frusemide were administered at 18.00 h on Day 1 and followed by dietary sodium restriction. In study A, after 38 h of sodium depletion, a second dose of frusemide was administered at 08.00 h on Day 3. In study B, after 14 h of sodium depletion, the effect of administration of 100 mg spironolactone or 45 mg prorenoate potassium (another aldosterone antagonist) at 08.00 h on Day 2 was compared with that of a placebo.

After the first dose of frusemide in study A, the mean plasma prolactin concentration correlated negatively with the urinary Na and K excretion over 5 h. After 38 h sodium depletion, the plasma prolactin concentration correlated positively with urinary Na excretion following the second dose of frusemide. In study B, after Na depletion for 14 h the plasma prolactin concentration at 08.00 h on Day 2 had a positive correlation with the 24 h urinary log10 Na:K ratio following placebo administration and had negative correlations with the true urinary log10 Na:K ratio following spironolactone and prorenoate potassium administration.

Neither acute Na deprivation nor the administration of single doses of frusemide, spironolactone or prorenoate potassium appeared to affect the normal circadian rhythm of plasma prolactin concentrations which remained constant for each subject throughout the 3 months covered by the investigation.

The correlations of plasma prolactin concentration to renal excretion of electrolytes, with no evidence for a negative feedback control mechanism, suggest an indirect relationship between prolactin and renal function.
PLASMA AND ADRENAL CORTISOL CONCENTRATIONS IN FOETAL, NEWBORN AND MOTHER GUINEA-PIGS DURING THE PERINATAL PERIOD
Authors: DALLE M. , DELOST P.
Published: December 2008

Concentrations of cortisol, corticosterone and cortisone in the plasma and adrenal glands, liver glycogen and plasma glucose of foetal, newborn and mother guinea-pigs were estimated during the last 6 days of pregnancy and throughout the first 24 h post partum. At the same time progesterone was measured in the plasma of the mother. During the prepartum rise in foetal plasma cortisol levels and liver glycogen, no significant change in the foetal adrenal cortisol content was observed. The plasma and adrenal cortisol concentrations of the mother were much higher than those observed in the foetus and increased significantly before parturition. In the mother as in the foetus, cortisone and corticosterone represent only a small percentage of corticosteroids compared with cortisol. These results indicate that the autonomous capacity of foetal adrenals, inhibited by maternal secretions before term, appears suddenly at birth.
TESTOSTERONE CONCENTRATION IN THE FLUIDS OF SEMINIFEROUS TUBULES, THE INTERSTITIUM AND THE RETE TESTIS OF THE RAT
Authors: COMHAIRE F. H. , VERMEULEN A.
Published: December 2008

Testosterone was measured by radioimmunoassay in interstitial fluid, 'free-flow' seminiferous tubular fluid, obtained by micropuncture, and rete testis fluid from intact adult anaesthetized rats. Under non-stimulated conditions the concentration of testosterone in interstitial fluid was below the limit of detection in two rats and achieved a mean level of 150 ± 27 (s.e.m.) ng/ml in the remaining 17 determinations. The testosterone concentration of the seminiferous tubular fluid was below the limit of detection in two rats, and had a mean level in the remaining 15 determinations of 91 ± 14 ng/ml, which is significantly lower (P < 0·02) than that in interstitial fluid. The mean ratio of seminiferous tubular:interstitial fluid testosterone concentration calculated in 14 rats was 0·94 ± 0·24. This ratio was less than unity whenever the interstitial fluid testosterone concentration was more than 50 ng/ml, whereas in all animals with interstitial fluid testosterone of 50 ng/ml, or less, the ratio was greater than or equal to one. The mean testosterone concentration of rete testis fluid in 32 samples was 33 ± 3 ng/ml.

After HCG stimulation in 12 rats, testosterone concentration in interstitial fluid increased to a mean value of 660 ± 83 ng/ml, and in seminiferous tubular fluid to 460 ± 44 ng/ml; the difference between the two was significant (P < 0·05).

These results are discussed in relation to the presumed dilution of seminiferous tubular fluid in rete testis fluid and the role of androgen-binding proteins in the transport of steroids.
STUDIES ON THE DURATION OF THE BREEDING SEASON AND PHOTOREFRACTORINESS IN FEMALE FERRETS PINEALECTOMIZED OR TREATED WITH MELATONIN
Authors: THORPE PENELOPE A. , HERBERT J.
Published: December 2008

Oestrous ferrets became anoestrous on exposure to short photoperiods (8 h light: 16 h darkness, 8L:16D) at the summer solstice, and this effect was prevented by pinealectomy. Removal of the pineal alone did not alter the duration of oestrus in animals kept in natural daylight. Melatonin (1 mg, thrice weekly) given to oestrous ferrets kept in daylight also terminated oestrus prematurely. Animals made photorefractory by prolonged exposure to long photoperiods (14L:10D) became photosensitive again if either given melatonin or transferred to short photoperiods (8L:16D) for 7 weeks. These findings show that the pineal gland of the oestrous ferret is involved in the termination of oestrus when the animal is exposed to experimental short photoperiods. This is in addition to its role in inducing oestrus when anoestrous animals are exposed to long days, an effect shown previously. Thus, neither phase of the annual breeding cycle is altered by experimental lighting regimes in pinealectomized animals. Furthermore, some of the effects of short days (but not of long days), including that on photosensitivity, can be replicated by melatonin in the ferret.
STIMULATION OF NUCLEIC ACID AND PROTEIN SYNTHESIS IN THE EPIDIDYMIS AND ACCESSORY ORGANS OF THE RAT BY TESTOSTERONE
Authors: RAJALAKSHMI M. , PRASAD M. R. N.
Published: December 2008

The effects of a single dose of testosterone on the content of DNA, RNA and protein and the incorporation of [3H]phenylalanine into protein in the epididymis, vas deferens and ventral prostate of the rat were studied. A single dose of testosterone did not increase the weights of the accessory organs but restored the incorporation of [3H]phenylalanine into proteins in the caput, corpus and cauda epididymides, vas deferens and ventral prostate to the normal level. Within 1 h of hormone administration, significant increases in the content of DNA, RNA and protein were noticed in the cauda epididymidis and ventral prostate. The caput and corpus epididymides and vas deferens showed decreasing order of responsiveness to testosterone. These data are discussed with respect to the relative responsiveness of these organs to reinitiation of their function by administration of a single dose of testosterone. The new protein(s) synthesized in response to hormonal stimulation associated with growth and secretory activity of the cells may be different from the new protein macromolecules synthesized after hormone withdrawal or inhibition of hormone action which are involved in autolytic processes.
LORDOSIS BEHAVIOUR IN MALE, FEMALE AND ANDROGENIZED FEMALE RATS
Authors: SÖDERSTEN P.
Published: December 2008

Sex differences in the lordosis response of adult rats to ovarian hormones were studied in a series of experiments. Male rats were less sensitive to oestradiol benzoate (OB, a single injection of 10, 100 or 1000 μg/kg or seven daily injections of 2, 10 or 50 μg/kg) than were female rats. Oestradiol benzoate-primed (10 μg/kg) female, but not male, rats showed dose-dependent responses to progesterone (0·4, 2·0 or 10·0 mg/kg). Male rats responded clearly to progesterone (2 mg/rat) only when primed with a high dose of OB (100 μg/rat). Display of the whole pattern of female sexual behaviour was induced in male rats by treatment with 100 μg OB and 2 mg progesterone. Female rats treated with 1 mg testosterone propionate (TP) on day 4 of life, ovariectomized as adults and tested under the same endocrine conditions as the rats described above, retained behavioural OB sensitivity but responded poorly to progesterone. Evidence is presented that ovarian secretions during development significantly modify the response of neonatally TP-treated and normal female rats to OB in adulthood.
PLASMA CONCENTRATIONS OF PROLACTIN AND THYROTROPHIN DURING SUCKLING IN URETHANE-ANAESTHETIZED RATS
Authors: BURNET F. R. , WAKERLEY J. B.
Published: December 2008

Plasma levels of prolactin and TSH were determined by radioimmunoassay in urethane-anaesthetized lactating rats during suckling. Oxytocin release was monitored by recording intramammary pressure. Application of ten pups, 3 h after administration of urethane (1·1 g/kg, i.p.), evoked a parallel rise in prolactin and TSH concentrations which reached a maximum during the 3rd hour of suckling and then declined. Peak hormone concentrations represented a 25-fold increase in prolactin and a ten-fold increase in TSH. Suckling also elicited a pulsatile (every 5–10 min) release of 0·5–1·0 mu. oxytocin. The gradual rise in prolactin and TSH occurred between the 1st and 20th oxytocin pulses.

Intravenous injection of thyrotrophin-releasing hormone (TRH) into unsuckled, anaesthetized lactating rats resulted in a 7- to 30-fold increase in TSH concentration, whereas prolactin levels showed no substantial change.

These results indicate that suckling releases TSH as well as prolactin in the urethane-anaesthetized rat. However, the absence of prolactin release after injections of TRH makes it unlikely that both endocrine responses are regulated solely by the actions of this one releasing hormone.
SERUM FOLLICLE-STIMULATING HORMONE, LUTEINIZING HORMONE AND PROGESTERONE CONCENTRATIONS IN PSEUDOPREGNANT RATS TREATED WITH MEDROXYPROGESTERONE ACETATE
Authors: DE GREEF W. J. , DULLAART J. , ZEILMAKER G. H.
Published: December 2008

Pseudopregnant rats were treated early in pseudopregnancy with 1 or 10 mg medroxyprogesterone acetate (MPA). Serum FSH, LH and progesterone concentrations were determined on days 2–20 of pseudopregnancy in treated and control rats.

The mean duration of pseudopregnancy was 13·5 days in the control animals, but when animals were treated with 1 mg MPA a dioestrous period of 21·4 days was observed. A period with leucocytic vaginal smears of at least 2 months was observed after treatment with 10 mg MPA.

Injection with MPA on day 3 of pseudopregnancy did not affect the serum FSH concentrations during the subsequent days. The progesterone pattern was alike in the three groups of animals, i.e. the duration of the activity of the corpora lutea was similar in all groups. However, 10 mg MPA slightly lowered progesterone concentrations on days 4–8 of pseudopregnancy. In the saline-treated rats, LH concentrations decreased from days 2–5, and remained low until they increased after day 11 of pseudopregnancy. This increase was delayed until day 20 in the animals treated with 1 mg MPA, and was not observed in the animals treated with 10 mg MPA.

It is argued that the increase of LH concentration at the end of pseudopregnancy is not instrumental in the decrease of peripheral progesterone concentration but rather that the decrease in the progesterone concentration leads to the increase in the LH concentration.
SECRETION OF LUTEINIZING HORMONE CAUSED BY CONTINUOUS INFUSIONS OF LUTEINIZING HORMONE RELEASING HORMONE IN THE LONG-TERM OVARIECTOMIZED RAT: EFFECT OF OESTROGEN PRETREATMENT
Authors: SCHUILING G. A. , GNODDE H. P.
Published: December 2008

Continuous infusions of luteinizing hormone releasing hormone (LH-RH) into phenobarbitone-treated long-term ovariectomized rats, resulted in patterns of LH secretion which were determined by the blood LH-RH concentration. Infusions of 52 ng LH-RH/h caused steadily increasing plasma LH levels, which stabilized after about 2 h of infusion and were maintained for the rest of the experiment (9 h).

A similar course of plasma LH concentration was observed as a result of infusions of 104 ng LH-RH/h, though in this case LH concentrations reached higher levels than those induced by infusion of 52 ng LH-RH/h. Higher rates of LH-RH infusion (208 and 416 ng/h), however, induced clear-cut LH peaks, which reached their maximal plasma values after 2–3 h of infusion and then declined again until, at the end of the experiment, they were only slightly higher than the LH levels induced by infusions of 52 ng LH-RH/h.

A similar series of LH-RH infusions given to ovariectomized rats pretreated with oestradiol benzoate during 3 days (the rats were injected daily with 7 μg steroid), produced a highly augmented response of the pituitary gland, but all LH-RH concentrations infused induced rather sharp LH peaks, reaching their maximum after 2–3 h of infusion. After 5 h of infusion the descending parts of all these peaks appeared to converge.

In both control and oestradiol benzoate-pretreated rats there appeared to be a linear relationship between the logarithm of the blood LH-RH concentration and the maximal plasma LH values on one hand, and the amount of LH secreted during the first 5 h of infusion on the other. Furthermore, it appeared that the longer the period of oestrogen action, the more the response of the pituitary gland to a certain dose of LH-RH was enhanced.
SERUM CORTICOSTERONE IN RATS WITH DELAYED ANOVULATION
Authors: RAMALEY JUDITH A.
Published: December 2008

The purpose of this study was to investigate adrenal function in rats during the development of persistent oestrus to determine whether a change in blood levels of corticosterone would precede or coincide with the onset of infertility. The syndrome of delayed persistent oestrus and anovulation was induced by administration of a low dose (10 μg) of testosterone propionate (TP) at 5 days of age. Control animals were handled without injection or received the vehicle (sesame oil) only. Half of each group was ovariectomized at weaning and received Silastic implants of either oestradiol benzoate (OB) or cholesterol, 3 mm tube length/100 g body weight. Intact rats given the low TP dose showed precocious vaginal opening (27·3 ± 2·1 days v. 37·6 ± 2·4 (s.e.m.) days in unhandled controls) and ovulated within 2 days. Persistent vaginal cornification developed in 22 out of 26 rats by 75 days of age. The TP-treated rats had higher corticosterone values than the controls and did not show a further increase after OB implantation. Cholesterol implantation depressed corticosterone levels in the TP-treated rats. The effects of the low TP dose were not dependent upon gonadal function since they persisted in ovariectomized rats. The results suggest that early exposure to androgen can modify the sensitivity of the adrenal system to oestrogen, and can also lead to persistently high values of corticosterone which are not depressed by ovariectomy. These changes precede the onset of persistent oestrus.
PITUITARY–ADRENAL FUNCTION IN THYROPARATHYROIDECTOMIZED MALE AND FEMALE RATS
Authors: DUNN J. D. , HESS M. E.
Published: December 2008

The influence of thyroid hormones on pituitary–adrenal function was assessed by studying several aspects of adrenocortical function approximately 30 days after thyroparathyroidectomy (TPTx). Both male and female rats showed evidence of rhythmic adrenocortical activity; peak plasma corticosterone levels occurred just before the dark phase of the lighting schedule. Only the amplitude of the rhythm appeared altered by TPTx. Peak plasma corticosterone levels in TPTx male and female animals were less (P < 0·05) than corresponding levels in intact control rats. Both sexes showed significant responses to stress, but the morning stress response in TPTx females was less (P < 0·01) than the stress response in intact controls. Concomitant with the reduced stress response, the adrenocortical response to exogenous ACTH was reduced in TPTx female rats.
PROSTAGLANDINS IN THE PLASMA AND AMNIOTIC FLUID OF RHESUS MONKEYS DURING PREGNANCY AND AFTER INTRA-UTERINE FOETAL DEATH
Authors: MITCHELL M. D. , PATRICK J. E. , ROBINSON J. S. , THORBURN G. D. , CHALLIS J. R. G.
Published: December 2008

Prostaglandin F (PGF) was measured in amniotic fluid, and 13,14-dihydro-15-keto-prostaglandin F2α (PGFM) was measured in maternal peripheral venous plasma and amniotic fluid of rhesus monkeys during late pregnancy. 13,14-Dihydro-15-keto-PGF2α was determined in the maternal peripheral venous plasma of two animals following intrauterine foetal death. The mean concentration of PGF and PGFM in amniotic fluid increased fourfold during the last 5 days of pregnancy. This increase was associated with an increase in the oestrone concentration in amniotic fluid and in maternal plasma. In normal pregnancy there was no increase in PGFM levels in the maternal peripheral vein, up to 1–2 days pre partum. After intra-uterine death, progesterone concentration in the maternal peripheral vein was unaltered, but oestrone and oestradiol declined. In plasma samples taken within 12 h of delivery, the concentration of PGFM was raised. It is concluded that an increase in prostaglandin production accompanies delivery at normal term, and at delivery past term following intra-uterine foetal death.
INDUCTION OF LUTEINIZING HORMONE RELEASE BY GONADAL STEROIDS IN THE OVARIECTOMIZED DOMESTIC HEN
Authors: WILSON SUSAN C. , SHARP P. J.
Published: December 2008

The ability of intramuscular injections of gonadal steroids to exert a positive feedback action on LH secretion was investigated in the ovariectomized hen. Plasma LH was measured by radioimmunoassay.

Single injections of progesterone (dose range: 0·05–10 mg/kg) or oestradiol benzoate (dose range: 0·01–1 mg/kg) did not result in an increase in plasma LH concentration. After priming with 0·1 mg oestradiol benzoate/kg on alternate days for 7 days and with 0·5 mg progesterone/kg on days 5, 6 and 7, a single injection of progesterone on day 8 (dose range: 0·1–2 mg/kg) caused the plasma LH concentration to start increasing after 15 to 30 min. Peak LH concentration was reached around 1·5–2 h after injection. The magnitude of LH response to progesterone was dose related. In contrast, a single injection of oestradiol benzoate (dose range: 0·01–1 mg/kg) failed to stimulate LH release in the oestrogen– progesterone primed ovariectomized (O-P-OVX) hen. A single injection of testosterone (dose range: 0·1–2·0 mg/kg) failed to stimulate LH release in ten out of 12 O-P-OVX hens. A small increase in LH secretion was observed in the two remaining birds.

When oestrogen or progesterone was omitted from the priming schedule, a LH positive feedback response to a single injection of progesterone was not observed. Increasing or decreasing the amount of oestrogen or progesterone in the priming schedule modified the LH response to a single injection of progesterone on the day following the last priming injection. This suggested that a critical oestrogen to progesterone ratio was required to prime the LH positive feedback mechanism.

It is suggested that, in the hen, the release of LH is facilitated by the positive feedback effect of a combination of oestrogen and progesterone in a two-phase process. The first is the priming phase, which depends on the presence in the blood of oestrogen and progesterone; the second is the inductive phase, which depends only on an incremental change in plasma progesterone concentration. Oestrogen is not involved in the inductive phase.
INHIBITION OF PITUITARY PROLACTIN SECRETION BY HUMAN PLACENTAL LACTOGEN IN RATS
Authors: NAGASAWA HIROSHI , YANAI REIKO , YAMANOUCHI KOREHITO
Published: December 2008

Intact female rats given twice daily injections of 1 mg human placental lactogen (HPL) showed continued dioestrous vaginal smears and their ovarian corpora lutea were found to be hypertrophied and functional. The serum prolactin level was significantly lower in these rats than in the controls at dioestrus as well as at pro-oestrus. Twice-daily injections of 0·5 or 2 mg HPL to ovariectomized rats decreased serum and pituitary levels of prolactin and increased hypothalamic activity of prolactin inhibiting hormone, although the effect was less at the lower dose. Human placental lactogen had no direct effect on pituitary prolactin secretion in vitro. These findings have demonstrated that HPL, like prolactin itself, inhibits prolactin secretion by acting indirectly on the pituitary through the hypothalamus.
TESTOSTERONE SECRETION BY FOETAL RAT TESTES IN VITRO
Authors: PICON RÉGINE
Published: December 2008

Testosterone secretion by foetal rat testes (13½–21½ days of gestation) explanted for 3 days in a synthetic medium was measured every 24 h by radioimmunoassay.

During the first day of explantation, the foetal testis produced, respectively, 1013 ± 132, 8734 ± 1118, 9179 ± 2185 and 3886 ± 309 (s.e.m.) pg/testis when explanted at 14½, 16½, 18½ and 21½ days respectively.

Testosterone production by 13½-day-old testes was not detectable on the first day of culture, but appeared on subsequent days. Daily testosterone secretion increased on the 2nd and 3rd days of culture in 14½-day-old testes and decreased in older stages. These results suggest that the functional differentiation of the testis is independent of stimulatory factors like gonadotrophins.

Dibutyryl cyclic AMP was found to stimulate testosterone production significantly from 14½ days of gestation onwards.
EFFECT OF INTRAVENOUS OR INTRA-AMNIOTIC INJECTION OF DEHYDROEPIANDROSTERONE SULPHATE ON OESTROGEN LEVELS IN URINE AND SERUM IN LATE PREGNANCY WITH LIVE ANENCEPHALIC FOETUSES
Authors: MAEYAMA M. , ICHIMARU S. , NAKAHARA K. , NAKAYAMA M. , MIYAKAWA I.
Published: December 2008

Dehydroepiandrosterone sulphate (DHAS) was injected intravenously or intra-amniotically into eight volunteers carrying live anencephalic foetuses (including one microcephalic foetus). Urinary and unconjugated serum oestrone, oestradiol and oestriol were measured before and after DHAS administration. In seven pregnant women with live anencephalic foetuses the urinary excretion of oestriol was very low, and the ratio of oestriol to oestrone+ oestradiol was much less than that during normal pregnancy. Increases of urinary oestrone and oestradiol but no significant change in the ratio of oestriol to oestrone + oestradiol were observed 24 h after i.v. administration of DHAS to five patients. In three patients, between 1 and 12 h after i.v. administration of DHAS (100–200 mg), the concentrations of serum oestrone, oestradiol and oestriol increased to 13·5, 6·8 and 3·1 times the control values, respectively. After injection of DHAS (200 mg) intra-amniotically into two patients, the urinary excretion of all three oestrogens increased much more on day 2 than on day 1, and the ratio of urinary oestriol to oestrone + oestradiol rose greatly. On the other hand, the concentrations of unconjugated serum oestrogens in these patients increased progressively between 1 and 12 h or more after DHAS administration, and the maximal level of serum oestriol was 9·8 times the control value while those of oestrone and oestradiol were 4·6 times and 5·0 times the control values, respectively. These results suggest that in late human pregnancy DHAS in the circulation of the mother is converted to oestriol largely via the phenolic pathway (DHAS → oestrone → oestriol), whereas DHAS circulating within the foeto-placental compartment is converted to oestriol via both the phenolic and the neutral intermediates.
HYPOTHALAMIC, PITUITARY AND TESTICULAR FUNCTION DURING SEXUAL MATURATION OF THE MALE RAT
Authors: PAYNE A. H. , KELCH R. P. , MURONO E. P. , KERLAN J. T.
Published: December 2008

Hypothalamic content of gonadotrophin-releasing hormone (GnRH), serum LH and FSH, capacity of the testis to synthesize testosterone in vitro, and testicular 5-ene-3β-hydroxysteroid dehydrogenase-isomerase and 17β-hydroxysteroid dehydrogenase were measured in groups of rats at approximately 5 day intervals from birth to day 64 and at days 74 and 89. The capacity of the testes to synthesize testosterone in vitro was measured in the presence of a saturating dose of rat LH. Gonadotrophin-releasing hormone increased steadily from 0·17 ng per hypothalamus at birth to a maximum of 7 ng at day 52 and then remained constant. LH concentrations were highly variable and often exceeded adult values between days 10 and 32. After day 32 a steady rise was observed which reached adult values between days 37 and 42. FSH concentrations markedly increased from 255 ng/ml observed at birth and day 10 to a peak value of 1000 ng/ml at day 32. Subsequently there was a steady decline in FSH values until day 74 when the concentration returned to values found at birth. 5-ene-3β-Hydroxysteroid dehydrogenase-isomerase activity exhibited a rapid increase between days 12 and 19 followed by an even greater rate of increase between days 19 and 32 when adult levels were attained. 17β-Hydroxysteroid dehydrogenase activity was very low between birth and day 22. Enzyme activity began to increase at day 22 with a rapid increase in activity observed between days 37 and 58. The increase in capacity to synthesize testosterone closely followed the increase in 17β-hydroxysteroid dehydrogenase activity. The study demonstrates that during sexual maturation in the male rat, changes in serum LH and FSH do not reflect changes in hypothalamic GnRH. The appearance of Leydig cells as monitored by 5-ene-3β-hydroxysteroid dehydrogenase-isomerase activity precedes by approximately 20 days the increase in testicular capacity to synthesize testosterone in vitro. The latter coincides with the increase in 17β-hydroxysteroid dehydrogenase activity. These results suggest that 17β-hydroxysteroid dehydrogenase is a limiting factor in the ability of the testis to respond to LH stimulation.
OVARIAN VENOUS BLOOD FLOW IN NON-PREGNANT AND PREGNANT RATS
Authors: BRUCE N. W. , DIMMITT S. B.
Published: December 2008

A modified venous outflow technique was used to measure ovarian blood flow in the rat. The rate of flow through the right ovary was 0·198 ± 0·009 (s.e.m.), 0·476 ± 0·076 and 0·958 ± 0·162 ml/min in six Day 0 (dioestrous), five Day 16 and six Day 22 pregnant rats respectively. The intravenous administration of 50 i.u. human chorionic gonadotrophin increased ovarian blood flow by 26 ± 4, 57 ± 19 and 46 ± 9% respectively, from 2 to 8 min after the injection. The present ovarian venous outflow results are substantially higher than those previously reported in the rat but agree with values determined with radioactive microspheres.
ENZYMIC CHANGES IN THE CERVIX OF THE RAT AND HAMSTER DURING THE OESTROUS CYCLE AND THE EFFECT OF STEROIDS
Authors: ZACHARIAH ELIZABETH , MOUDGAL N. R.
Published: December 2008

Changes in four hydrolytic enzymes, namely acid phosphatase, alkaline phosphatase, arylsulphatase A and B, of the cervix of the rat and hamster have been studied during the 4-day oestrous cycle. All four enzymes showed maximal activity on the day of oestrus and least activity on day 2 of dioestrus. All the enzymes showed significant reduction of activity after ovariectomy, arylsulphatase A and B showing the earliest changes in specific activity.

A single subcutaneous injection of 0·02 μg oestradiol-17β/rat increased the specific activity of arylsulphatase A and B from the low ovariectomized level to that observed in control oestrous animals within 18 and 6 h respectively. A higher concentration of oestradiol-17β (2·0 μg) had an inhibitory effect. Progesterone was without effect on arylsulphatase B activity, but when given (2·0 mg) with 0·02 μg oestradiol-17β, it inhibited the response to oestrogen.

Cycloheximide prevented the rise in arylsulphatase B activity occurring after oestrogen injection, suggesting a regulation of cervical arylsulphatase B at the level of protein biosynthesis. These results suggest that arylsulphatase B activity may be induced by oestrogen in the cervix of the rat.
STEROIDOGENESIS IN HUMAN FOLLICLES APPROACHING OVULATION AS JUDGED FROM ASSAYS OF FOLLICULAR FLUID
Authors: FOWLER R. E. , CHAN S. T. H. , WALTERS D. E. , EDWARDS R. G. , STEPTOE P. C.
Published: December 2008

Human chorionic gonadotrophin (HCG) was given to patients at mid-cycle before the endogenous LH surge. Graafian follicles were aspirated 32–33 h later, before ovulation was expected, and the levels of several steroids in follicular fluid and in matching serum samples were measured by radioimmunoassay. Two types of Graafian follicle were identified at laparoscopy, based on the nature of the oocyte, granulosa cells and follicular fluid withdrawn from the follicles. Some were large, preovulatory and presumably becoming luteinized while others were generally smaller, non-ovulatory and still growing.

The concentrations of dehydroepiandrosterone (DHEA) and 17α-hydroxypregnenolone (Δ5 intermediates), androstenedione and testosterone were higher in non-ovulatory follicles, whereas large follicles usually contained high levels of progesterone, 17α-hydroxyprogesterone, pregnenolone and oestradiol-17β. A cluster analysis of these data grouped follicles into two distinct clusters, which accorded with their identification as ovulatory or non-ovulatory at laparoscopy.

Levels of progesterone, 17α-hydroxyprogesterone and oestradiol-17β in follicular fluid were high in preovulatory follicles in comparison with plasma. Results in two patients indicated that plasma levels of these steroids were determined by the preovulatory follicle. Levels of plasma Δ5 steroids were closer to follicular fluid concentrations, whereas DHEA was higher in plasma.

The role of the theca and granulosa is discussed in relation to the synthesis of progesterone and oestradiol-17β in follicles as ovulation approaches.
MECHANISM OF INCREASED PROLACTIN SECRETION BY SULPIRIDE
Authors: MACLEOD R. M. , ROBYN CLAUDE
Published: December 2008

The effect of sulpiride, a neuroleptic agent, on the secretion of prolactin by the anterior pituitary gland of the rat was studied. A significant increase in serum prolactin was observed after subcutaneous administration of the drug. Although sulpiride (0·10μmol/l or 0·14 mmol/l) had no effect on the secretion of newly synthesized or radioimmunoassayable prolactin in vitro, the drug significantly overcame the inhibitory action that dopamine (0·50 μmol/l) exerted on prolactin secretion. Rats implanted with a prolactin-secreting pituitary tumour MtTW15 showed an inhibition of prolactin biosynthesis and release. Injection of these rats with sulpiride restored prolactin biosynthesis and release of the hormone toward normal levels. These results demonstrate that sulpiride has a direct effect on the pituitary antagonizing the inhibitory effects exerted by dopaminergic mechanisms, although the drug itself does not stimulate the secretion of prolactin in vitro. Sulpiride may have a direct action on the pituitary lactotrophs in vivo, but effects at higher centres have not been excluded.
DEVELOPMENTAL CHANGES IN THE RESPONSES OF THE ADRENAL GLANDS OF FOETAL SHEEP TO ENDOGENOUS ADRENOCORTICOTROPHIN, AS INDICATED BY HORMONE RESPONSES TO HYPOXAEMIA
Authors: JONES C. T. , BODDY K. , ROBINSON J. S. , RATCLIFFE J. G.
Published: December 2008

The change in plasma ACTH and corticosteroid concentrations in response to a 60 min period of hypoxaemia were studied in foetal and adult sheep during the latter half of pregnancy. Hypoxaemia consistently caused large rises in the concentration of ACTH in foetal plasma, the magnitude of which did not change with gestational age but was related to the physiological state of the foetus. Before 139 days small and slow rises in corticosteroid (predominantly cortisol) concentration in foetal plasma were observed during hypoxaemia, and these may have been of maternal origin. After 139 days, hypoxaemia caused a rapid and large rise in the concentration of cortisol and corticosterone in foetal plasma, which was largely of foetal origin. Hypoxaemia caused no consistent change in maternal plasma ACTH concentration but was associated with progressive increases in plasma cortisol concentrations. The cortisol:corticosterone ratio in foetal plasma was 1·5 before 139 days and increased to 4·1 several days before term which was lower than the value of 9 in maternal plasma. Small concentrations of 11-deoxycortisol and cortisone were detected in maternal and foetal plasma, the changes of which were small during hypoxaemia.

The results indicate that a maturational change in the sensitivity of the foetal adrenal to endogenous ACTH occurs several days before term.
EFFECT OF METHALLIBURE ON GONADOTROPHIC CONTENT, OVARIAN 32P UPTAKE AND GONADOSOMATIC INDEX IN THE FRESHWATER CATFISH, HETEROPNEUSTES FOSSILIS (BLOCH)
Authors: SINGH T. P. , RAIZADA R. B. , SINGH AJAY KUMAR
Published: December 2008

Gonadotrophin content in the pituitary gland and blood serum as well as ovarian 32P uptake were studied in response to methallibure treatment in H. fossilis. There was a marked reduction in the gonadotrophic activity of the pituitary gland and blood serum within 3 weeks of methallibure treatment (100 μg/g). A simultaneous significant reduction was also recorded in the ovarian activity of these fish. The fall in ovarian activity caused by methallibure could not be prevented by the administration of LH, FSH or LH + FSH. After cessation of methallibure treatment, LH + FSH (50 μg each) administration restored ovarian activity. It is evident from these results that methallibure alters the secretion of gonadotrophin, and also prevents its action on the ovary.
CONTROL OF ADRENOCORTICOTROPHIN SECRETION BY CATECHOLAMINES IN THE PREGNANT AND FOETAL SHEEP
Authors: JONES C. T. , ROBINSON R. O. , LUTHER E. , RITCHIE J. W. K. , WORTHINGTON D.
Published: December 2008

The effect of adrenaline on the maternal and foetal plasma ACTH concentration of twelve pregnant sheep with chronically implanted vascular catheters has been studied. Adrenaline infused into the jugular vein of the ewe or foetus produced carotid arterial adrenaline concentrations of 1–9 ng/ml. The foetal plasma ACTH was 253 ± 73 pg/ml and it showed a fivefold increase during adrenaline infusion; the ACTH concentration achieved was proportional to the plasma adrenaline. In the ewes plasma ACTH was 99 ± 23 pg/ml. During adrenaline infusion to the ewes this rose by an amount dependent on the adrenaline concentration achieved and there was also a rise in foetal plasma ACTH but no consistent change in foetal plasma adrenaline. There was no reproducible change in plasma corticosteroid concentration during adrenaline infusion into the foetus but a rise in maternal plasma corticosteroid concentration during infusion into the ewes. Because the adrenaline concentrations achieved during the infusions were within the physiological range, the results indicate that circulating catecholamines may directly or indirectly influence the concentration of ACTH in the circulation. Also, physiological rises in plasma catecholamines in pregnant animals may stimulate the release of ACTH from the foetal pituitary.
A POSSIBLE INTERRELATIONSHIP BETWEEN GONADOTROPHIN STIMULATION AND PROSTAGLANDIN F2α INHIBITION OF STEROIDOGENESIS BY GRANULOSA-LUTEAL CELLS IN VITRO
Authors: HENDERSON K. M. , McNATTY K. P.
Published: December 2008

The newly formed corpus luteum of many species is refractory to the lytic action of prostaglandin F2α (PGF2α). This phenomenon was studied utilizing porcine, bovine and human granulosa-luteal cells in tissue culture. The steroidogenic potential of the granulosa-luteal cells was critical in determining whether PGF2α could inhibit progesterone production. Since the steroidogenic potential of the granulosa-luteal cell is related to the amount of LH bound to the cell, the bound LH may protect the granulosa-luteal cells from the lytic action of PGF2α. Finally, a 'see-saw' type of interaction between LH and PGF2α is postulated to account for the resistance of the newly formed corpus luteum to PGF2α
HORMONE RECEPTOR LEVELS AND HORMONE, RNA AND PROTEIN METABOLISM IN THE GENITAL TRACT DURING THE OESTROUS CYCLE OF THE EWE
Authors: MILLER B. G. , MURPHY LEIGH , STONE G. M.
Published: December 2008

The concentrations of soluble oestradiol and progesterone receptor proteins and several metabolic activities were measured in the genital tracts of ewes killed on Days 0 (oestrus), 2, 5, 10 or 14 of the oestrous cycle. In caruncular endometrium and in whole uterus the concentrations of oestradiol receptor (pmol steroid bound/mg tissue DNA) were highest at oestrus and declined steadily thereafter to minimal values at Day 14. The concentrations of progesterone receptor were highest on Days 0–5, then declined to low levels on Days 10–14. There was little metabolism of either [3H]oestradiol or [3H]progesterone in minces of whole uterus and with either steroid the pattern of metabolism did not change at any stage of the cycle. The in-vivo rates of synthesis of protein in caruncular endometrium and in isthmic oviduct were highest at or shortly after oestrus (Days 0–2), then declined to low levels on Days 10–14. RNA:DNA ratios in these two tissues were also greatest at oestrus and subsequently fell to minimal values by Day 14. The results are discussed in relation to ovarian secretion of oestradiol and progesterone during the oestrous cycle of the ewe.
PARTURITION IN GOATS: STUDIES ON THE INTERACTIONS BETWEEN THE FOETUS, PLACENTA, PROSTAGLANDIN F AND PROGESTERONE BEFORE PARTURITION, AT TERM OR AT PARTURITION INDUCED PREMATURELY BY CORTICOTROPHIN INFUSION OF THE FOETUS
Authors: CURRIE W. B. , THORBURN G. D.
Published: December 2008

Relationships between foetal corticosteroid concentrations, utero-ovarian prostaglandin F (PGF) and maternal peripheral progesterone have been examined in detail in goats shortly before spontaneous parturition at term. Foetal corticosteroids increased during the last 13-11 days of gestation and particularly sharply during the last 3 days and even during advanced labour. About 24 h before parturition, acute releases of PGF were evident in the vein draining the pregnant uterine horn, and these corresponded closely to the time of luteal regression. Further release of PGF occurred when progesterone declined to low levels, probably reflecting the course of labour.

The changes observed before premature parturition, induced by infusing ACTH into foetal goats, were similar except for the more rapid increase in foetal corticosteroid concentrations. Immature neonates born after ACTH treatment were viable, placental delivery was normal and lactogenesis occurred in the mothers indicating that the treatment promoted full expression of the critical perinatal events. The early, acute releases of PGF were ipsilateral to the ACTH-infused foetus and were luteolytic provided the corpora lutea were also on that side. Luteolysis failed or was abnormally delayed if the corpora lutea were contralateral and prolonged ACTH treatment of the foetuses in such cases caused foetal death probably because of premature failure of the placenta. Similar findings were noted if ACTH infusion of the foetus was accompanied by simultaneous progesterone treatment of the mothers in order to block the induction of labour. It was suggested that placental changes occurring during foetal hypercortisolism might be caused by increased placental oestrogen synthesis and the effect of this on the foeto-maternal junction along with a stimulatory action on PG synthesis in the maternal placenta. Experimental disruption of the normal sequence of events, when labour was blocked by progesterone, proved to be lethal to the foetus if the loss of placental integrity progressed sufficiently.

The chain of regulatory signals linking increased activity of the foetal adrenal with parturition thus appears to involve stimulation of oestrogen biosynthesis, PGF release from the maternal placenta and the start of physical changes at the placental junction. Provided the foetus and corpora lutea are ipsilateral, the early releases of PGF effect luteolysis and a withdrawal of progesterone from the maternal circulation. When progesterone concentrations are sufficiently low, labour is initiated and its progress reflected by further release of PGF. The control mechanisms, which also provide for the final maturation of the foetus, clearly enable a close synchronization of the various perinatal events which are essential for the transition from foetal to postnatal life.
CHANGES IN AGGRESSIVE AND SEXUAL RESPONSIVENESS OF MALE GOLDEN HAMSTERS AFTER NEONATAL ANDROGEN ADMINISTRATION
Authors: PAYNE A. P.
Published: December 2008

On day 1 after birth, male golden hamsters received either 300 μg of an androgen (testosterone propionate, testosterone, dihydrotestosterone or androstenedione) in 0·03 ml arachis oil, or oil alone. As intact adults, their aggressiveness towards unreceptive females was measured. After this, all animals were castrated. At least 3 weeks after the operation all animals received oestradiol benzoate (10 μg + progesterone (500 μg), after which their capacity to show patterns of female sexual behaviour towards a stud male was tested. Control hamsters which had received oil as neonates showed less aggression than the females with which they interacted; these controls also readily assumed lordosis after castration and priming with ovarian steroids. Conversely, animals which had received testosterone propionate or androstenedione neonatally were as aggressive as the female hamsters, and showed a markedly decreased ability to display lordotic behaviour after castration. The behaviour of male hamsters which received testosterone or dihydrotestosterone was unaffected. Thus, at the level of treatment used, increased aggressiveness appeared to co-vary with a decreased capacity to show female sexual behaviour patterns. However, within each treatment there was little evidence of such a relationship at the level of the individual animal.
AN HOMOLOGOUS RADIOIMMUNOASSAY FOR CHICKEN FOLLICLE-STIMULATING HORMONE: OBSERVATIONS ON THE OVULATORY CYCLE
Authors: SCANES C. G. , GODDEN PATRICIA M. M. , SHARP P. J.
Published: December 2008

A highly purified FSH preparation has been used to develop a specific homologous radioimmunoassay for chicken FSH which is sufficiently sensitive and precise to measure the hormone in small samples (10–100μl) of plasma. The assay was used to measure plasma FSH in the chicken and turkey.

The FSH concentration was higher in sexually mature chickens than in juvenile birds and further elevated after castration or ovariectomy. In turkeys, it was lower in birds held on a short daily photoperiod than in birds held on a long daily photoperiod. FSH rose in sexually quiescent female turkeys after injection of synthetic LH-releasing hormone and was increased in laying hens after injection of progesterone.

No major changes were observed in FSH concentration during the chicken ovulatory cycle, although there was a small increase between 15 and 14 h before ovulation.
CHANGES IN PITUITARY RESPONSIVENESS TO LUTEINIZING HORMONE RELEASING HORMONE IN RAMS EXPOSED TO ARTIFICIAL PHOTOPERIODS
Authors: LINCOLN G. A.
Published: December 2008

Six adult Soay rams were subjected to an artificial lighting régime of alternating 4 month periods of long days (16 h light: 8 h darkness) and short days (8 h light: 16 h darkness) which induced a seasonal cycle in testicular development and regression during a period of 32 weeks. On 15 occasions during the study pituitary responsiveness was assessed by measuring the concentration of luteinizing hormone (LH) in jugular blood samples collected at frequent intervals after the intravenous injection of 1 pg synthetic luteinizing hormone releasing hormone (LH-RH).

It was shown that both the magnitude and duration of the induced release of LH changed in relation to the photoperiod; the magnitude was greatest during long days when the rams were sexually quiescent, while the duration of the LH release was greatest during short days at the peak of testicular activity. This pattern of responsiveness was modified by implantation of the rams with testosterone.
ANTERIOR PITUITARY SENSITIVITY IN IMMATURE FEMALE RATS STIMULATED WITH GONADOTROPHIN RELEASING HORMONE IN VIVO: EFFECT OF PRIMING WITH OESTROGEN, PREGNANT MARE SERUM GONADOTROPHIN OR BRAIN LESION
Authors: DE ZIEGLER D. , WILKINSON M. , CASSARD DANIELLE , RUF K. B.
Published: December 2008

An investigation of pituitary sensitivity, assessed in terms of increments in plasma LH and FSH concentrations, to stimulation with one or two injections of gonadotrophin releasing hormone (GnRH) was carried out on 26-day-old immature female rats which had received one of the following priming treatments: 10 μg oestradiol benzoate (OB) as a single injection on day 23 or day 25, or on both days; 10 i.u. pregnant mare serum gonadotrophin (PMSG) on day 24; an electrochemical brain lesion placed in the mediobasal hypothalamus on day 23; control animals received either vehicle alone or a sham lesion.

Pituitary sensitivity assessed at 10.00 h on day 26, after one or two injections of GnRH (100 ng/100 g body weight, s.c.), was enhanced to a similar degree in the three groups treated with OB in terms of LH (P < 0-01). The FSH response also increased after OB treatment but was not statistically significant. In contrast, 48 h after the injection of PMSG (i.e. when the rats were in a 'pro-oestrous-like' condition) pituitary sensitivity in terms of both LH and FSH dropped sharply (P < 0·001). In lesioned animals, pituitary sensitivity to one injection of GnRH was unchanged. A second GnRH injection administered after a 60 min interval induced a slightly larger LH response in control animals. In contrast, the ratio of the second response to the first increased in animals treated with PMSG, despite the state of overall decrease in sensitivity, being 4·5:1 in PMSG-treated rats versus 1·4:1 in controls.

In a second set of experiments, we investigated the variation of pituitary sensitivity in conjunction with an experimentally induced gonadotrophin surge. In animals treated with OB on day 23 and with 1 mg progesterone at 12·00 h on day 26, pituitary sensitivity was increased at both 14.00 and 17.00 h as compared with that in the day 23 OB-treated group at 10.00 h. The PMSG-treated animals maintained their state of decreased responsiveness at 14.00 h, but exhibited increased pituitary sensitivity at the time of the gonadotrophin surge (17.00 h).

These results show that OB increases pituitary sensitivity to GnRH in 26-day-old female rats and that the induction of a gonadotrophin surge further increases this sensitivity. In contrast, PMSG-treated rats displayed a state of decreased responsiveness 48 and 52 h, but not 55 h, after the injection. Pituitary sensitivity on the second day after PMSG treatment thus clearly differs from that observed during pro-oestrus in the adult cyclic female rat.
EFFECT OF HYPOPHYSECTOMY ON p-AMINOHIPPURATE TRANSPORT KINETICS IN RAT RENAL CORTICAL SLICES
Authors: MISANKO B. S. , PARK Y. S. , SOLOMON S.
Published: December 2008

Recent work on kidneys from hypophysectomized (hypox) rats has shown atrophy of the proximal tubules with no effects on the other parts of the nephron. We carried out experiments to determine whether the reduction of p-aminohippurate (PAH) is consistent with structural changes in the proximal tubule of hypophysectomized rats. Initial velocities of PAH uptake by renal cortical slices were found to be constant over 30 min of incubation at concentrations of PAH up to 0·5 mmol/l for both control and hypox animals. Using kinetic analysis, it was found that both maximal velocity, Vmax, and the Michaelis constant, Km, were reduced in hypox animals, the relative reduction being similar for both parameters. Comparison between high Na (100 mmol/l) and low Na (6 mmol/l) media indicated that in both control and hypox rats, Vmax was significantly lower in low Na medium than in high Na medium, whereas Km was not changed. Efflux of PAH from pre-loaded tissue also showed a reduction in hypox animals. These results may indicate that hypophysectomy alters the capacity of PAH transport in renal cortical slices by (1) reducing the effective transport area or sites, and (2) by changing carrier–substrate affinity.