Effects of catecholamine synthesis inhibitors and adrenergic receptor antagonists on restraint-induced LH release

1995 ◽  
Vol 144 (3) ◽  
pp. 511-515 ◽  
Author(s):  
A I Martín ◽  
J Fernández-Ruiz ◽  
A López-Calderón
Keyword(s):  
Adrenergic Receptor ◽  
Acute Stress ◽  
Male Rats ◽  
Receptor Antagonists ◽  
Catecholamine Synthesis ◽  
Serum Lh ◽  
Propranolol Treatment ◽  
Lh Release ◽  
Lh Secretion

Abstract Acute stress is known to increase LH secretion and the release of central norepinephrine (NE) in intact rats. Studies were performed to analyse the role of catecholamines in acute stress-induced LH release in male rats. Injection of α-methyl-p-tyrosine (αMPT) and diethyldithiocarbamate (DDC), catecholamine synthesis inhibitors, significantly decreased both hypothalamic concentration of NE and serum LH. Restraint for 30 min evoked an increase in serum LH in saline-treated rats, whereas αMPT and DDC administration blocked the stress-induced LH release. The effects of α1-, α2- and β-adrenoreceptor antagonists on the LH response to restraint stress were also studied. Propranolol treatment did not modify serum LH in either unstressed or stressed rats. The two α-adrenergic receptor antagonists prazosin and yohimbine prevented the restraint-induced LH release; however, prazosin but not yohimbine significantly decreased the serum concentration of LH in unstressed rats. These data suggest that the acute stress-induced increase in LH secretion is mediated through the activation of α2-adrenergic receptors. Journal of Endocrinology (1995) 144, 511–515

Adrenal progesterone facilitates the negative feedback of oestrogen on LH release in ovariectomized rats

1993 ◽  
Vol 139 (2) ◽  
pp. 253-258 ◽  
Author(s):  
A. M. Salicioni ◽  
R. W. Carón ◽  
R. P. Deis
Keyword(s):  
Ovariectomized Rats ◽  
Adrenal Steroids ◽  
Serum Progesterone ◽  
Oestrogen Treatment ◽  
Ovx Rats ◽  
Serum Lh ◽  
Oestradiol Benzoate ◽  
Lh Release ◽  
Lh Secretion

ABSTRACT There is evidence that the adrenals play a role in the regulation of the synthesis and release of gonadotrophins in various vertebrates. The aim of this study was to determine the part played by adrenal steroids, with special reference to progesterone, on the concentration of LH in ovariectomized (OVX) and oestrogen-primed rats. OVX rats received a single s.c. injection of vehicle or oestradiol benzoate (OB, 20 μg/rat). This day was designated as day 0. Three or four days later (day 3–day 4), the rats were treated with mifepristone (10 mg/kg) or with two doses of progesterone antiserum and blood samples were obtained at 13.00 and 18.00 h. OB treatment of OVX rats reduced serum LH at 13.00 h and 18.00 h on day 3 but only at 13.00 h on day 4. The administration of mifepristone at 08.00 h to OVX and oestrogen-treated rats induced a significant increase in serum LH at 18.00 h on days 3 and 4, without modifying the values at 13.00 h. When mifepristone was given at 13.00 h a much larger increase in serum LH was obtained at 18.00 h. In OVX and oestrogen-treated rats, adrenalectomy on day 2 (08.00–09.00 h) induced an increase in serum LH at 18.00 h similar to that observed in the OVX and oestrogen-primed rats after mifepristone treatment. In order to determine the specificity of the effect of mifepristone, a group of OVX and oestrogentreated rats was injected with progesterone antiserum at 08.00 and 13.00 h on day 3. Serum LH concentrations at 13.00 and 18.00 h on day 3 were similar to values obtained in OVX rats treated with oestrogen and mifepristone. Serum progesterone was measured at 08.00 and 13.00 h in OVX and OVX and oestrogenprimed rats. At both times, values were similar in OVX rats but oestrogen treatment significantly increased serum progesterone levels. The important role of adrenal progesterone on the regulation of LH secretion in OVX and oestrogen-primed rats is evident from these results. Blocking progesterone action at the receptor level, we showed that OB significantly increased LH values at 18.00 h. On the basis of these studies it is tempting to speculate on the possibility of an inhibitory or stimulatory effect of oestrogen on serum LH concentration in OVX rats, according to the presence or absence of adrenal progesterone action. Journal of Endocrinology (1993) 139, 253–258

EFFECTS OF NALOXONE ON LUTEINIZING HORMONE AND PROLACTIN IN SERUM OF RATS

1980 ◽  
Vol 85 (2) ◽  
pp. 307-315 ◽  
Author(s):  
M. S. BLANK ◽  
A. E. PANERAI ◽  
H. G. FRIESEN
Keyword(s):  
Female Rats ◽  
Male Rats ◽  
Ovariectomized Rats ◽  
Serum Prolactin ◽  
Immature Female ◽  
Subcutaneous Injections ◽  
Serum Lh ◽  
Opiate Peptides ◽  
Lh Release ◽  
Lh Secretion

The effects of subcutaneous injections of the opiate antagonist naloxone on the tonic and phasic secretion of prolactin and LH were studied in rats. During development, resting levels of prolactin in serum were decreased by naloxone (2·5 mg/kg body wt) on days 24,45 and 50 in female rats and on days 28,45 and 50 in male rats. In the adult, naloxone (2·5 mg/kg body wt) decreased basal levels of serum prolactin in male rats and levels during oestrus in female rats. In 25-day-old female rats, serum LH rose from resting levels within 7·5 min of naloxone administration (2·5 mg/kg body wt) and returned to pretreatment levels by 30 min, while prolactin fell by 7·5 min and remained low for as long as 60 min after treatment. Furthermore, a tenfold lower dose of naloxone (0·25 mg/kg body wt) did not raise basal levels of serum LH but still decreased resting levels of serum prolactin in immature female rats (24 days old). The effect of naloxone (2·5 mg/kg body wt) on phasic LH release was studied in 29-day-old immature female rats primed on day 27 with pregnant mare serum gonadotrophin (PMSG). In these PMSG-treated rats the onset of the prolactin surge was blunted by naloxone while it had no effect on phasic LH release. Naloxone (5 mg/kg body wt) also induced a rise in levels of serum LH in ovariectomized rats and, if administered with morphine, it reversed the short-term inhibition of LH secretion caused by morphine. However, naloxone was ineffective after pretreatment with oestradiol benzoate. These findings suggest that the responses of serum LH and prolactin to naloxone were dissociated and that oestrogens and opiate peptides may have interacted to regulate secretion of LH.

The role of oestrogens on gonadotrophin secretion in the testicular feminization syndrome1

1980 ◽  
Vol 95 (3) ◽  
pp. 314-318 ◽  
Author(s):  
Martha Medina ◽  
Alfredo Ulloa-Aguirre ◽  
Maria A. Fernández ◽  
Gregorio Pérez-palacios
Keyword(s):  
Clomiphene Citrate ◽  
Poor Response ◽  
Testicular Feminization ◽  
Normal Response ◽  
Serum Lh ◽  
Gonadotrophin Secretion ◽  
Before And After ◽  
Complete Form ◽  
Lh Secretion

Abstract. The role of oestrogens on gonadotrophin secretion was assessed in three related patients with the complete form of testicular feminization syndrome. Serum LH and FSH levels were measured before and after I.RH stimulation as well as before, during and after chronic clomiphene citrate administration. Moderately elevated LH basal levels with a significant LH rise following I.RH were observed. Normal or even low FSH level with poor response to LRH were found in all subjects. Administration of clomiphene citrate resulted in a significant serum LH increase without any change of FSH. Following castration both LH and FSH rose and a normal response to LRH was observed. These results were interpreted as demonstrating that, while endogenous oestrogens modulate LH secretion in patients with androgen unresponsiveness, it plays no role in regulating FSH secretion and suggested that a factor of testicular origin without androgenic or oestrogenic activity is responsible for FSH regulation.

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 Characterization of the Role of NKA in the Control of Puberty Onset and Gonadotropin Release in the Female Mouse

Endocrinology ◽  
2019 ◽  
Vol 160 (10) ◽  
pp. 2453-2463 ◽  
Author(s):  
Silvia León ◽  
Chrysanthi Fergani ◽  
Rajae Talbi ◽  
Serap Simavli ◽  
Caroline A Maguire ◽  
...  
Keyword(s):  
Sex Steroids ◽  
Neurokinin A ◽  
Central Control ◽  
Gnrh Release ◽  
Lh Release ◽  
Timing Of Puberty ◽  
Puberty Onset ◽  
Lh Secretion

Abstract The tachykinin neurokinin B (NKB, Tac2) is critical for proper GnRH release in mammals, however, the role of the other tachykinins, such as substance P (SP) and neurokinin A (NKA) in reproduction, is still not well understood. In this study, we demonstrate that NKA controls the timing of puberty onset (similar to NKB and SP) and stimulates LH release in adulthood through NKB-independent (but kisspeptin-dependent) mechanisms in the presence of sex steroids. Furthermore, this is achieved, at least in part, through the autosynaptic activation of Tac1 neurons, which express NK2R (Tacr2), the receptor for NKA. Conversely, in the absence of sex steroids, as observed in ovariectomy, NKA inhibits LH through a mechanism that requires the presence of functional receptors for NKB and dynorphin (NK3R and KOR, respectively). Moreover, the ability of NKA to modulate LH secretion is absent in Kiss1KO mice, suggesting that its action occurs upstream of Kiss1 neurons. Overall, we demonstrate that NKA signaling is a critical component in the central control of reproduction, by contributing to the indirect regulation of kisspeptin release.

Comparison of the LH secretion patterns in the male rat following infusion of LRH and of the LRH-analogue buserelin®. Influence of castration and oestradiol benzoate on the efficiency of LH release

1983 ◽  
Vol 102 (2) ◽  
pp. 196-204 ◽  
Author(s):  
G. A. Schuiling ◽  
N. Pols-Valkhof ◽  
T. R. Koiter
Keyword(s):  
Area Under The Curve ◽  
Male Rats ◽  
Male Rat ◽  
Potency Ratio ◽  
Maximal Height ◽  
Oestradiol Benzoate ◽  
Lh Release ◽  
Buserelin Treatment ◽  
Pre Treatment ◽  
Lh Secretion

Abstract. The LH releasing activities of LRH and the LRH-analogue buserelin® (HOE 766; (D-Ser (But)6-LRH(1–9)nona peptide-ethylamide) were compared in intact and short- and long-term castrated male rats, pre-treated (either 1 or 3 days) with oestradiol benzoate (EB) or oil. LRH and buserelin were infused iv at the constant rate of 104 ng/h for 21 h. Blood samples were taken from an intracarotid cannula. LH responses were judged on the basis of the mean maximal height of the LH concentration (MH; ng LH/ml plasma) and a parameter of total LH release, i.e. the area under the curve of LH concentrations plotted against time ('area under the curve', AUC; expressed in 'area units'). The release efficiency of LRH and buserelin, E (see for a definition: Materials and Methods), which informs on the total quantity of LH released in relation to pituitary LH content, was calculated by dividing the AUC × 100 by the pituitary LH content at the beginning of stimulation. Maximal plasma LH concentrations were observed between t= 1.5 and t=3 h after LRH and between t= 1.5 and t=9 after buserelin treatment. Both with LRH and buserelin the rise of LH secretion was greater the longer the animals were castrated and/or pre-treated with EB. The buserelin-induced LH response (with the exception of the responses induced in the EB-pre-treated, 4-weeks castrated rat) were about 2–2.5 times higher (MH) and larger (AUC) than the corresponding LRH-induced responses. The buserelin/LRH potency ratio, therefore, is about 2–2.5. EB-pre-treatment did not change the pituitary LH content. It therefore enhanced the efficiency of release of LH of both LRH and buserelin. Castration, on the other hand, caused an increase of the pituitary LH content: after 4 weeks it was raised by a factor 4. Since, however, the LH responses induced by LRH and buserelin were proportionally higher and larger, castration did not significantly change the efficiency of LH release. The results indicate that the efficiency of LH release can be changed by changes in the endocrine environment in the experimental animals, whilst for the magnitude of LH responses the pituitary LH content is also important. It is therefore suggested that the responsiveness of the pituitary gland to LRH (and agonistic analogues) is determined by (1) the state of the LH secretion mechanism and (2) the pituitary LH content.

EFFECT OF SYNTHETIC THYROTROPHIN RELEASING FACTOR ON PROLACTIN AND LUTEINIZING HORMONE SECRETION IN MALE AND FEMALE RATS DURING VARIOUS REPRODUCTIVE STATES

1975 ◽  
Vol 67 (3) ◽  
pp. 425-430 ◽  
Author(s):  
R. P. DEIS ◽  
NIA ALONSO
Keyword(s):  
Hormone Secretion ◽  
Female Rats ◽  
Male Rats ◽  
Serum Prolactin ◽  
Serum Prolactin Level ◽  
Luteinizing Hormone Secretion ◽  
Male And Female Rats ◽  
Serum Lh ◽  
The Mean ◽  
Lh Secretion

SUMMARY The effect of synthetic thyrotrophin releasing factor (TRF) on serum prolactin and LH concentrations was determined by radioimmunoassay in male, cyclic and pseudopregnant female rats. A solution of TRF (0·1, 0·25, 0·5 and 1 μg/rat) was injected i.v. at 17.00 h into rats pretreated with sodium pentobarbitone at 13.00 h. A group of male rats was also treated with TRF at 11.00 h after pretreatment with sodium pentobarbitone at 07.00 h. Fifteen minutes after TRF administration, blood samples were obtained by heart puncture. Doses of 0·25, 0·5 and 1 μg TRF significantly increased the serum prolactin concentration in pro-oestrous rats. The mean serum prolactin level after the injection of 0·5 and 1 μg into oestrous rats and 0·5 μg TRF into dioestrous day 2 rats, was significantly greater than the control values. Injection of TRF on day 1 of dioestrus had no effect. Serum LH concentration was not significantly modified by the various doses of TRF administered. On day 3 of pseudopregnancy a significant increase of serum prolactin values was obtained with 0·5 and 1 μg TRF. On day 7 of pseudopregnancy a dose of 0·5 μg produced the same effect, but on day 10 of pseudopregnancy only 1 μg TRF significantly increased serum prolactin levels when compared with the control rats. In male rats serum prolactin concentration was significantly greater than the control values after TRF treatment either in the morning or the afternoon. The response was similar to that obtained in pro-oestrous rats. The results suggest that the ability of synthetic TRF to stimulate prolactin release exists in both female and male rats and that TRF does not affect LH secretion.

The N-methyl-d-aspartate receptor antagonist MK-801 delays the onset of puberty and may acutely block the first spontaneous LH surge and ovulation in the rat

1991 ◽  
Vol 131 (3) ◽  
pp. 435-441 ◽  
Author(s):  
H. M. A. Meijs-Roelofs ◽  
P. Kramer ◽  
E. C. M. van Leeuwen
Keyword(s):  
Nmda Receptors ◽  
Receptor Antagonist ◽  
Acute Treatment ◽  
Physiological Role ◽  
Female Rat ◽  
Mk 801 ◽  
Aspartate Receptor ◽  
Serum Lh ◽  
Lh Secretion

ABSTRACT The physiological role of activated hypothalamic N-methyl-d-aspartate (NMDA) receptors during the final phase of female sexual maturation was explored in the rat. The effects of administration of the specific non-competitive receptor antagonist MK-801 on the occurrence of first ovulation and on LH secretion were studied. Injections of MK-801 (0·1–0·2 mg/kg body wt, s.c.) were given once or twice daily, starting at 28 or 35 days of age and continuing up to the day of first ovulation, resulted in a significant delay of this ovulation. Rats that were treated daily with 0·2 mg MK-801/kg, starting on days 30 or 34 and continuing up to day 38, but not including the day of first pro-oestrus, also showed retarded first ovulation. No decrease in serum LH concentration, compared with control rats, could be detected in these rats. Acute treatment with MK-801 (one or two injections of 0·2, or one injection of 0·5 mg/kg) given at 11.30 h (and 16.00 h) on the day of first pro-oestrus produced partial (1 × 0·2 mg/kg) or complete (2×0·2 and 1 × 0·5 mg/kg) blockade of first ovulation; blocked rats ovulated 1 day later. Serum LH concentrations at 16.00 h on the day of pro-oestrus were significantly decreased in all MK-801-treated groups compared with saline-injected control rats. At 19.00 and 22.00 h LH concentrations remained low in all non-ovulating MK-801-treated rats, but increased in the MK-801-treated rats that ovulated. Thus chronic blockade of the NMDA receptors by the antagonist MK-801 delays but does not prevent first ovulation, whereas acute treatment blocks the pro-oestrous LH peak. It was concluded that activation of NMDA receptors plays an important role both in tonic and preovulatory LH secretion during the onset of puberty in the female rat. Journal of Endocrinology (1991) 131, 435–441

scholarly journals Influences of Serotonin Hydrochloride on Adiponectin, Ghrelin and KiSS1 Genes Expression

2020 ◽  
Vol 9 ◽  
Author(s):  
Fariba Mahmoudi ◽  
Khadijeh Haghighat Gollo
Keyword(s):  
Gene Expression ◽  
Saline Group ◽  
Polymerase Chain Reaction Method ◽  
Male Rats ◽  
Expression Levels ◽  
Serum Lh ◽  
Genes Expression ◽  
Lh Release ◽  
The Mean ◽  
Gene Expression Levels

Background: Serotonin and kisspeptin stimulates gonadotropin-releasing hormone (GnRH) and luteinizing hormone (LH) release while ghrelin and adiponectin inhibit them. In the present experimental study, the effects of central injection of serotonin were investigated on LH concentration, KiSS1, adiponectin, and ghrelin genes expression. Materials and Methods: Fifteen Wistar male rats in three groups received saline or serotonin hydrochloride via the third cerebral ventricle. Blood samples were collected via the tail vein. Serum LH concentration and relative gene expression were evaluated by radioimmunoassay and real-time polymerase chain reaction method, respectively. Results: Serotonin significantly increased the mean serum LH concentration and  KiSS1 gene expression levels compared to the saline group. Serotonin significantly decreased the mean ghrelin and adiponectin genes expression levels compared to the saline group. Conclusion: The serotonergic pathway may have stimulatory effects on hypothalamic kisspeptin synthesis, partly via inhibiting hypothalamic ghrelin and adiponectin neural activity.[GMJ.2020;9:e1767]

scholarly journals Propranolol, but not naloxone, enhances spinal reflex bladder activity and reduces pudendal inhibition in cats

2015 ◽  
Vol 308 (1) ◽  
pp. R42-R49 ◽  
Author(s):  
Marc J. Rogers ◽  
Zhiying Xiao ◽  
Bing Shen ◽  
Jicheng Wang ◽  
Zeyad Schwen ◽  
...  
Keyword(s):  
Receptor Antagonist ◽  
Nerve Stimulation ◽  
Adrenergic Receptor ◽  
Bladder Capacity ◽  
Spinal Reflex ◽  
Saline Control ◽  
Tibial Nerve Stimulation ◽  
Bladder Activity ◽  
Propranolol Treatment

This study examined the role of β-adrenergic and opioid receptors in spinal reflex bladder activity and in the inhibition induced by pudendal nerve stimulation (PNS) or tibial nerve stimulation (TNS). Spinal reflex bladder contractions were induced by intravesical infusion of 0.25% acetic acid in α-chloralose-anesthetized cats after an acute spinal cord transection (SCT) at the thoracic T9/T10 level. PNS or TNS at 5 Hz was applied to inhibit these spinal reflex contractions at 2 and 4 times the threshold intensity (T) for inducing anal or toe twitch, respectively. During a cystrometrogram (CMG), PNS at 2T and 4T significantly ( P < 0.05) increased bladder capacity from 58.0 ± 4.7% to 85.8 ± 10.3% and 96.5 ± 10.7%, respectively, of saline control capacity, while TNS failed to inhibit spinal reflex bladder contractions. After administering propranolol (3 mg/kg iv, a β1/β2-adrenergic receptor antagonist), the effects of 2T and 4T PNS on bladder capacity were significantly ( P < 0.05) reduced to 64.5 ± 9.5% and 64.7 ± 7.3%, respectively, of the saline control capacity. However, the residual PNS inhibition (about 10% increase in capacity) was still statistically significant ( P < 0.05). Propranolol treatment also significantly ( P = 0.0019) increased the amplitude of bladder contractions but did not change the control bladder capacity. Naloxone (1 mg/kg iv, an opioid receptor antagonist) had no effect on either spinal reflex bladder contractions or PNS inhibition. At the end of experiments, hexamethonium (10 mg/kg iv, a ganglionic blocker) significantly ( P < 0.05) reduced the amplitude of the reflex bladder contractions. This study indicates an important role of β1/β2-adrenergic receptors in pudendal inhibition and spinal reflex bladder activity.

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