scholarly journals Neuromedin S as Novel Putative Regulator of Luteinizing Hormone Secretion

Endocrinology ◽  
2007 ◽  
Vol 148 (2) ◽  
pp. 813-823 ◽  
Author(s):  
E. Vigo ◽  
J. Roa ◽  
M. López ◽  
J. M. Castellano ◽  
R. Fernandez-Fernandez ◽  
...  
Keyword(s):  
Suprachiasmatic Nucleus ◽  
Hormone Secretion ◽  
Ovariectomized Rats ◽  
Potential Contribution ◽  
Female Rat ◽  
Central Administration ◽  
Luteinizing Hormone Secretion ◽  
Dark Light ◽  
Potential Implication ◽  
Reproductive Axis

Neuromedin S (NMS), a 36 amino acid peptide structurally related to neuromedin U, was recently identified in rat brain as ligand for the G protein-coupled receptor FM4/TGR-1, also termed neuromedin U receptor type-2 (NMU2R). Central expression of NMS appears restricted to the suprachiasmatic nucleus, and NMS has been involved in the regulation of dark-light rhythms and suppression of food intake. Reproduction is known to be tightly regulated by metabolic and photoperiodic cues. Yet the potential contribution of NMS to the control of reproductive axis remains unexplored. We report herein analyses of hypothalamic expression of NMS and NMU2R genes, as well as LH responses to NMS, in different developmental and functional states of the female rat. Expression of NMS and NMU2R genes was detected at the hypothalamus along postnatal development, with significant fluctuations of their relative levels (maximum at prepubertal stage and adulthood). In adult females, hypothalamic expression of NMS (which was confined to suprachiasmatic nucleus) and NMU2R significantly varied during the estrous cycle (maximum at proestrus) and was lowered after ovariectomy and enhanced after progesterone supplementation. Central administration of NMS evoked modest LH secretory responses in pubertal and cyclic females at diestrus, whereas exaggerated LH secretory bursts were elicited by NMS at estrus and after short-term fasting. Conversely, NMS significantly decreased elevated LH concentrations of ovariectomized rats. In summary, we provide herein novel evidence for the ability of NMS to modulate LH secretion in the female rat. Moreover, hypothalamic expression of NMS and NMU2R genes appeared dependent on the functional state of the female reproductive axis. Our data are the first to disclose the potential implication of NMS in the regulation of gonadotropic axis, a function that may contribute to the integration of circadian rhythms, energy balance, and reproduction.

POSSIBLE ROLE OF 5α-ANDROSTANE-3α,17β-DIOL IN THE CONTROL OF FOLLICLE-STIMULATING HORMONE SECRETION IN THE IMMATURE FEMALE RAT

1982 ◽  
Vol 92 (1) ◽  
pp. 37-42 ◽  
Author(s):  
H. M. A. MEIJS-ROELOFS ◽  
P. KRAMER ◽  
L. GRIBLING-HEGGE
Keyword(s):  
Inhibitory Action ◽  
Combined Treatment ◽  
Hormone Secretion ◽  
Inhibitory Effect ◽  
Ovariectomized Rats ◽  
Female Rat ◽  
Immature Rat ◽  
Rat Strain ◽  
Intact Rats

A possible role of 5α-androstane-3α,17β-diol (3α-androstanediol) in the control of FSH secretion was studied at various ages in ovariectomized rats. In the rat strain used, vaginal opening, coincident with first ovulation, generally occurs between 37 and 42 days of age. If 3α-androstanediol alone was given as an ovarian substitute, an inhibitory effect on FSH release was evident with all three doses tested (50, 100, 300 μg/100 g body wt) between 13 and 30 days of age; at 33–35 days of age only the 300 μg dose caused some inhibition of FSH release. Results were more complex if 3α-androstanediol was given in combined treatment with oestradiol and progesterone. Given with progesterone, 3α-androstanediol showed a synergistic inhibitory action on FSH release between 20 and 30 days of age. However, when 3α-androstanediol was combined with oestradiol a clear decrease in effect, as compared to the effect of oestradiol alone, was found between 20 and 30 days of age. Also the effect of combined oestradiol and progesterone treatment was greater than the effect of combined treatment with oestradiol, progesterone and 3α-androstanediol. At all ages after day 20 none of the steroid combinations tested was capable of maintaining FSH levels in ovariectomized rats similar to those in intact rats. It is concluded that 3α-androstanediol might play a role in the control of FSH secretion in the immature rat, but after day 20 the potentially inhibitory action of 3α-androstanediol on FSH secretion is limited in the presence of oestradiol.

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.

COMPARISON OF FOLLICLE-STIMULATING HORMONE AND LUTEINIZING HORMONE SECRETION AFTER ELECTRICAL STIMULATION OF THE PREOPTIC PART OF THE HYPOTHALAMUS IN FEMALE RATS ANAESTHETIZED WITH ETHYL CARBAMATE OR SODIUM PENTOBARBITONE

1978 ◽  
Vol 78 (1) ◽  
pp. 151-152 ◽  
Author(s):  
R. G. DYER ◽  
M. B. TER HAAR ◽  
LINDA C. MAYES
Keyword(s):  
Electrical Stimulation ◽  
Luteinizing Hormone ◽  
Follicle Stimulating Hormone ◽  
Hormone Secretion ◽  
Control Process ◽  
Female Rats ◽  
Female Rat ◽  
Luteinizing Hormone Secretion ◽  
Stimulation Of ◽  
Stimulating Hormone

A.R.C. Institute of Animal Physiology, Babraham, Cambridge, CB2 4AT (Received 17 January 1978) For over 30 years, the method by which the brain regulates the secretion of gonadotrophic hormones has been studied by electrical stimulation of those parts of the central nervous system thought to be implicated in the control process. Much of the work has been performed on the female rat. In this species, anaesthetic doses of sodium pentobarbitone, administered immediately before the pro-oestrous 'critical period', block the preovulatory surge of luteinizing hormone (LH) for 24 h. The same treatment also reduces the early phase of the pro-oestrous secretion of follicle-stimulating hormone (FSH; Daane & Parlow, 1971). Electrical stimulation of the preoptic part of the hypothalamus can overcome this blocking effect and analysis of the optimum parameters required to restore normal secretion of gonadotrophins may give some insight into the endogenous process (e.g. Everett, 1965; Fink & Aiyer, 1974;

CIRCADIAN RHYTHM OF LUTEINIZING HORMONE SECRETION IN THE OVARIECTOMIZED RAT IMPLANTED WITH OESTRADIOL

1977 ◽  
Vol 75 (2) ◽  
pp. 251-260 ◽  
Author(s):  
G. CHAZAL ◽  
M. FAUDON ◽  
F. GOGAN ◽  
M. HERY ◽  
C. KORDON ◽  
...  
Keyword(s):  
Circadian Rhythm ◽  
Hormone Secretion ◽  
Plasma Concentrations ◽  
Ovariectomized Rats ◽  
Luteinizing Hormone Secretion ◽  
Implantation Time ◽  
Light Darkness ◽  
Lh Rh ◽  
Lh Releasing Hormone ◽  
Afternoon Peak

Implantation of a solid source of oestradiol into ovariectomized rats produced constant plasma concentrations of the hormone over a long period of time. Under these conditions, LH is released in a circadian pattern with a very marked peak in the afternoon. This circadian rhythm is synchronized to the light–darkness cycle, since it follows exactly a shift in the nycthemeral cycle. The first peak appeared on day 3 after placement of the oestrogen implant; its amplitude was constant from days 3 to 9 after implantation, and decreased gradually during prolonged implantation. The afternoon peak was not correlated with changes in the pituitary sensitivity to exogenous LH releasing hormone (LH-RH), since the LH response to increasing doses of the peptide could be superimposed in the morning and in the afternoon. However, the decreased amplitude of the rhythm observed after more than 9 days of implantation seemed to depend upon a progressive desensitization of the pituitary gland to LH-RH. Pituitary LH content also decreased as a function of implantation time. It is concluded that, under conditions of constant plasma oestradiol concentrations and of constant pituitary sensitivity to LH-RH, a daily activation of the neural trigger releasing pituitary gonadotrophins occurs.

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