Influence of blood removal under ether anaesthesia on the release of prolactin during the oestrous cycle in the rat. Involvement of the ovaries

1982 ◽  
Vol 99 (2) ◽  
pp. 179-186 ◽  
Author(s):  
Nelly Boehm ◽  
Salomé Plas-Roser ◽  
Christine Lazarus ◽  
Claude Aron
Keyword(s):  
Positive Response ◽  
Vena Cava ◽  
Oestrous Cycle ◽  
Female Rats ◽  
Prolactin Release ◽  
Ether Anaesthesia

Abstract. The aim of this work was to study the stresslike effects of blood removal unter ether anaesthesia at different stages of the di-oestrus period in 4-day cyclic female rats. Blood removal by heart puncture or laparotomy and bleeding from the abdominal vena cava both under ether anaesthesia were shown to precipitously evoke prolactin release on di-oestrus I morning and on di-oestrus II afternoon. Adrenalectomy did not prevent this effect from occurring on di-oestrus I morning following either procedure of blood removal. Ovariectomy completely suppressed the stress-like effects of ether anaesthesia whereas progesterone appeared capable of restoring prolactin release under these circumstances. No prolactin positive response to ether anaesthesia was observed on di-oestrus II morning, in unoperated controln females.

Circulating blood progesterone is pulsatile throughout the rat oestrous cycle

1987 ◽  
Vol 116 (1) ◽  
pp. 121-128 ◽  
Author(s):  
Ok-Kyong Park ◽  
Victor D. Ramirez
Keyword(s):  
Jugular Vein ◽  
Recovery Period ◽  
Oestrous Cycle ◽  
Female Rats ◽  
Individual Data ◽  
Blood Samples ◽  
Ether Anaesthesia ◽  
Heparinized Saline ◽  
Freely Moving ◽  
First Time

Abstract. In the present experiment, we determined circulating progesterone (P4) levels of intact cycling female rats. A cannula constructed from polyethylene50 tubing containing heparinized saline was inserted into the jugular vein of the rat under light ether anaesthesia and after a 3–6 h recovery period sequential blood samples were withdrawn from unanaesthetized, freely-moving rats. Blood samples (80–100 μl) were collected at 10-min intervals for 6 h and the volume was replaced with saline. Plasma P4 was determined using a specific P4 radioimmunoassay. Four rats in each of three phases of the rat oestrous cycle (E, Dl, D2) were examined. In addition, rats in proestrus were divided into an early (EP, N = 4) and a late (LP, N = 4) proestrous conditions. Individual data were analyzed by PULSAR as adapted for an IBM-PC. P4 was found to fluctuate in a pulsatile mode throughout the rat oestrous cycle. Mean levels of circulating P4 were lowest (38.8 ± 1.7 nmol/l plasma) in EP and highest (122.5 ± 1.3) in Dl. The frequency of P4 pulses was dramatically decreased in Dl (2.50 ± 0.86 pulses/6 h), whereas no difference was found among the other days of the cycle (7.25 ± 0.47 in E, 7.25 ± 0.85 in D2, 5.75 ± 1.31 in EP, and 6.50 ± 1.04 in LP). Interestingly, the amplitude of P4 pulses was significantly lower in EP (14.0 ± 2.91 pmol), whereas no difference was found among other groups. Another group of experimental animals were ovariectomized (N = 4; two with and two without an implant of a silastic capsule of P4) and similarly bled. These animals demonstrated a fairly stable circulating pattern of P4. The present data demonstrate for the first time that P4 in rat blood fluctuates in a pulsatile manner.

NEW DATA CONCERNING THE ROLE PLAYED BY PROGESTERONE IN THE CONTROL OF FOLLICULAR GROWTH IN THE RAT

1974 ◽  
Vol 75 (3) ◽  
pp. 569-578 ◽  
Author(s):  
G. Buffler ◽  
S. Roser
Keyword(s):  
Wistar Rats ◽  
Venous Blood ◽  
Oestrous Cycle ◽  
Female Rats ◽  
Cycle Duration ◽  
Follicular Growth ◽  
The Third ◽  
Female Wistar Rats

ABSTRACT The mechanisms involved in the prolongation of the oestrous cycle following LH administration were studied in 4-day cyclic female Wistar rats. In females injected with LH on the morning of dioestrus I there was an increase in ovarian venous blood progesterone as compared with non-injected animals. In both LH-treated females, and those injected with progesterone on the morning of dioestrus I, a slowing up in follicular growth was observed from the afternoon of dioestrus I. The size of follicles greater than 400 urn present in LH or progesterone injected animals on the third day of cycle was similar to the size reached by the same range of follicles in non-injected animals on the second day of the cycle. Hence, the increase in endogenous ovarian progesterone elicited by LH was considered as the cause of the slowing up of follicular growth and therefore of the lengthening of the oestrous cycle duration in female rats injected with LH at the beginning of 4-day cycle.

Changes in the characteristics of pulsatile luteinizing hormone secretion during the oestrous cycle and after ovariectomy and oestrogen treatment in female rats

1982 ◽  
Vol 94 (2) ◽  
pp. 177-182 ◽  
Author(s):  
Takashi Higuchi ◽  
Masazumi Kawakami
Keyword(s):  
Hormone Secretion ◽  
Pulse Amplitude ◽  
Pulse Frequency ◽  
Oestrous Cycle ◽  
Female Rats ◽  
Ovariectomized Rats ◽  
Luteinizing Hormone Secretion ◽  
Oestrogen Treatment ◽  
Serum Lh ◽  
Lh Release

Changes in the characteristics of LH secretory pulses in female rats were determined in different hormonal conditions; during the oestrous cycle and after ovariectomy and oestrogen treatment. The frequency and amplitude of the LH pulses were stable during the oestrous cycle except at oestrus when a pattern could not be discerned because of low LH concentrations. These were significantly lower than those measured during other stages of the cycle. Mean LH concentrations and LH pulse amplitudes increased with time up to 30 days after ovariectomy. The frequency of the LH pulse was unchanged 4 days after ovariectomy when mean LH levels had already increased. The frequency increased 10 days after ovariectomy and then remained stable in spite of a further increase in mean serum LH concentrations. Oestradiol-17β injected into ovariectomized rats caused a decrease in LH pulse amplitude but no change in pulse frequency. One day after treatment with oestradiol benzoate no LH pulse was detectable, probably because the amplitude was too small. A generator of pulsatile LH release is postulated and an oestrogen effect on its function is discussed.

Involvement of norepinephrine in pituitary LH release induced by oestradiol in vitro

1984 ◽  
Vol 107 (2) ◽  
pp. 199-203
Author(s):  
A. Miyake ◽  
K. Tasaka ◽  
T. Aono
Keyword(s):  
Oestrous Cycle ◽  
Female Rats ◽  
Direct Effects ◽  
Significant Release ◽  
Lh Release ◽  
Lh Secretion ◽  
Perifusion System ◽  
Double Chamber

Abstract. The direct effects of oestradiol-17β (E2) on pituitary luteinizing hormone (LH) release and the role of norepinephrine (NE) in E2-induced gonadtrophin release were examined in a sequential double chamber perifusion system by perifusing the mediobasal hypothalami (MBH) and/or pituitaries excised from normally cycling female rats. Administration of E2 induced significant release (70–160% increase, P < 0.05) of LH from the pituitary of rats in pro-oestrus, but not in other stages of the oestrous cycle. When the MBH and the pituitary were perifused in sequence, E2 induced significant release of LH in all stages of the oestrous cycle except oestrus. When the pituitary from rats in dioestrus II was perifused alone with medium containing 200 ng/ml NE, significant release of LH (80–170% increase, P < 0.05) was observed after the administration of E2. The E2-induced LH release in pro-oestrus was completely abolished by perifusion with medium containing diethyldithiocarbamate, an inhibitor of NE synthesis. These findings suggest that NE may be involved in changes of pituitary responsiveness in LH secretion to oestrogen during the rat oestrous cycle.

scholarly journals Kisspeptin Stimulation of Prolactin Secretion Requires Kiss1 Receptor but Not in Tuberoinfundibular Dopaminergic Neurons

Endocrinology ◽  
2019 ◽  
Vol 160 (3) ◽  
pp. 522-533 ◽  
Author(s):  
Nayara S S Aquino ◽  
Ilona C Kokay ◽  
Carolina Thörn Perez ◽  
Sharon R Ladyman ◽  
Patricia C Henriques ◽  
...  
Keyword(s):  
Dopaminergic Neurons ◽  
Prolactin Secretion ◽  
Female Rats ◽  
Male Rats ◽  
Prolactin Release ◽  
Whole Cell Patch Clamp ◽  
Neuropeptide Ff ◽  
Concomitant Reduction ◽  
Prolactin Response

Abstract Kisspeptin has been shown to stimulate prolactin secretion. We investigated whether kisspeptin acts through the Kiss1 receptor (Kiss1r) to regulate dopamine and prolactin. Initially, we evaluated prolactin response in a Kiss1r-deficient mouse line, in which Kiss1r had been knocked into GnRH neurons (Kiss1r−/−R). Intracerebroventricular kisspeptin-10 (Kp-10) increased prolactin release in wild-type but not in Kiss1r−/−R female mice. In ovariectomized, estradiol-treated rats, the Kiss1r antagonist kisspeptin-234 abolished the Kp-10–induced increase in prolactin release but failed to prevent the concomitant reduction in the activity of tuberoinfundibular dopaminergic (TIDA) neurons, as determined by the 3,4-dihydroxyphenylacetic acid/dopamine ratio in the median eminence. Using whole-cell patch clamp recordings in juvenile male rats, we found no direct effect of Kp-10 on the electrical activity of TIDA neurons. In addition, dual-label in situ hybridization in the hypothalamus of female rats showed that Kiss1r is expressed in the periventricular nucleus of the hypothalamus (Pe) and arcuate nucleus of the hypothalamus (ARC) but not in tyrosine hydroxylase (Th)–expressing neurons. Kisspeptin also has affinity for the neuropeptide FF receptor 1 (Npffr1), which was expressed in the majority of Pe dopaminergic neurons but only in a low proportion of TIDA neurons in the ARC. Our findings demonstrate that Kiss1r is necessary to the effect of kisspeptin on prolactin secretion, although TIDA neurons lack Kiss1r and are electrically unresponsive to kisspeptin. Thus, kisspeptin is likely to stimulate prolactin secretion via Kiss1r in nondopaminergic neurons, whereas the colocalization of Npffr1 and Th suggests that Pe dopaminergic neurons may play a role in the kisspeptin-induced inhibition of dopamine release.

DEVELOPMENTAL, DIURNAL AND OESTROUS CYCLE-DEPENDENT CHANGES IN THE ACTIVITY OF LIVER ENZYMES

1976 ◽  
Vol 68 (2) ◽  
pp. 265-272 ◽  
Author(s):  
ÅKE STENBERG
Keyword(s):  
Enzyme Activities ◽  
Reductase Activity ◽  
Maximal Activity ◽  
Oestrous Cycle ◽  
Female Rats ◽  
Male Rats ◽  
Supernatant Fraction ◽  
Second Phase ◽  
Developmental Phase ◽  
Male And Female Rats

SUMMARY 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.

Permissive role of corticotropin-releasing factor in the acute stress-induced prolactin release in female rats

1995 ◽  
Vol 198 (2) ◽  
pp. 146-148 ◽  
Author(s):  
Tatsuo Akema ◽  
Atsuhiko Chiba ◽  
Morihiro Oshida ◽  
Fukuko Kimura ◽  
Jun-ichi Toyoda
Keyword(s):  
Acute Stress ◽  
Corticotropin Releasing Factor ◽  
Female Rats ◽  
Prolactin Release ◽  
Permissive Role

INDUCTION OF PROLACTIN AND LUTEINIZING HORMONE RELEASE BY HISTAMINE IN MALE AND FEMALE RATS AND THE INFLUENCE OF BRAIN TRANSMITTER ANTAGONISTS

1978 ◽  
Vol 76 (2) ◽  
pp. 193-202 ◽  
Author(s):  
A. O. DONOSO
Keyword(s):  
Prolactin Secretion ◽  
Oestrous Cycle ◽  
Female Rats ◽  
Male Rats ◽  
Intraventricular Injection ◽  
Hormone Release ◽  
Stimulatory Action ◽  
Male And Female Rats ◽  
Oestradiol Benzoate ◽  
Lh Release

The levels of prolactin and LH in the plasma of rats were determined at various times after intraventricular injection of histamine. Doses of 5 and 60 μg histamine (free base) in male rats, anaesthetized with ether, induced an increase in the level of prolactin in the plasma, whilst producing a slight decrease in the concentration of LH. Injection of 5 μg histamine at 14.00 h into female rats at all stages of the oestrous cycle caused prolactin to be released; the effect was greatest at oestrus and at day 1 of dioestrus. Histamine also gave rise to a marked increase in the level of LH in the plasma when administered to pro-oestrous rats, but had no effect when injected at the other stages of the oestrous cycle. The effect of histamine on the release of prolactin in ovariectomized, oestradiol benzoate: progesterone-primed (OVX,OB:P) rats was found to be dose-related, and the level of LH in the plasma was increased by as little as 1·25 μg. Pretreatment with adrenergic (phenoxybenzamine and propranolol) and cholinergic (atropine) antagonists failed to block the stimulatory effects of histamine on prolactin secretion, but pretreatment with methysergide (serotonin antagonist) increased the histamine-induced release of prolactin in male rats. Antagonists did not modify the response of prolactin to histamine in OVX,OB:P-primed rats. The histamine-induced release of LH in OVX,OB:P-primed rats was slightly reduced by pretreatment with phenoxybenzamine, propranolol and atropine, but not by methysergide. These results indicate that histamine facilitates the release of prolactin. The stimulatory action of histamine on both pro-oestrous and OVX,OB:P-primed but not male rats suggests that histamine may be involved in LH release in the rat. Results obtained in animals pretreated with transmitter antagonists, which were unable to prevent histamine-induced hormone release, suggest that the actions of this amine are not mediated by cholinergic, noradrenergic or serotonergic mechanisms.

PROLACTIN STIMULATION TEST WITH PERPHENAZINE: AN EVALUATION OF PLASMA PROLACTIN LEVELS AND PITUITARY SECRETORY ACTIVITY IN THE RAT

1976 ◽  
Vol 68 (3) ◽  
pp. 355-368 ◽  
Author(s):  
A. A. VAN DER GUGTEN ◽  
P. C. SAHULEKA ◽  
G. H. VAN GALEN ◽  
H. G. KWA
Keyword(s):  
Adult Male ◽  
Secretory Activity ◽  
Female Rats ◽  
Male Rats ◽  
Plasma Prolactin ◽  
Prolactin Release ◽  
Oestrogen Treatment ◽  
Endocrine Status ◽  
Pituitary Prolactin ◽  
Single Plasma

SUMMARY Many investigations of the regulation of prolactin synthesis and release are based on single plasma prolactin determinations. The purpose of the present experiment was to ascertain whether groups of rats (i.e. young or adult, male or female animals, being either intact, gonadectomized or gonadectomized and treated with oestrone), differing in age and/or endocrine status, will react to a single dose of perphenazine by an acute release of pituitary prolactin in proportion to their initial plasma prolactin levels. No consistent relation existed between the classification of the twelve groups of rats into three categories of basal plasma prolactin levels (i.e. < 20, 25–50, > 125 ng/ml) and their response to perphenazine. Even though all groups showed a highly significant increase of plasma prolactin levels the magnitude of the maximum prolactin response at 30 min varied greatly within the groups of one category and thus was not related to the initial prolactin levels. The effect of 14 days of oestrone treatment in increasing plasma prolactin levels in gonadectomized animals was greatest in young and adult male rats, less in young females and not significant in adult females. The results obtained after perphenazine treatment in the latter group made it clear that the effect of oestrogen treatment on prolactin release can be completely blocked by increasing synthesis and/or release of the prolactin-release inhibiting factor (PIF). Since perphenazine induces decrease of pituitary prolactin and a concomitant increase of plasma prolactin levels through lowered PIF-action, the positive effect of oestrogens on prolactin release (as observed in gonadectomized male and young female rats) apparently is caused by a different mode of action. The implications of these findings for the regulation of prolactin release, as affected by the endocrine status of the rat, is discussed. Moreover, comparison of prolactin lost from the pituitary and gained in the circulation of the experimental animals, with amounts of prolactin that were observed to disappear from plasma during the experiment, provided suggestive evidence that the capacity to synthesize and/or eliminate prolactin, after a sudden provoked release of the hormone, differed among the groups. The rates of synthesis by the pituitary, of release from the pituitary into the circulation as well as of elimination of the hormone from the circulation (equally involved in determining actual plasma levels) are thought, therefore, to be far more important for the elucidation of prolactin regulation than single plasma prolactin determinations.

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