scholarly journals A Direct Neurokinin B Projection from the Arcuate Nucleus Regulates Magnocellular Vasopressin Cells of the Supraoptic Nucleus

2016 ◽  
Vol 28 (4) ◽  
Author(s):  
R. Pineda ◽  
N. Sabatier ◽  
M. Ludwig ◽  
R. P. Millar ◽  
G. Leng
Keyword(s):  
Supraoptic Nucleus ◽  
Arcuate Nucleus ◽  
Neurokinin B

scholarly journals Neurokinin B Signaling in the Female Rat: a Novel Link Between Stress and Reproduction

Endocrinology ◽  
2014 ◽  
Vol 155 (7) ◽  
pp. 2589-2601 ◽  
Author(s):  
P. Grachev ◽  
X.F. Li ◽  
M.H. Hu ◽  
S.Y. Li ◽  
R.P. Millar ◽  
...  
Keyword(s):  
Opioid Receptor ◽  
Arcuate Nucleus ◽  
Pulse Generator ◽  
Ovariectomized Rats ◽  
Female Rat ◽  
Dynorphin A ◽  
Receptor Antagonists ◽  
Neurokinin B ◽  
Hypothalamic Arcuate Nucleus ◽  
Systemic Stress

Acute systemic stress disrupts reproductive function by inhibiting pulsatile gonadotropin secretion. The underlying mechanism involves stress-induced suppression of the GnRH pulse generator, the functional unit of which is considered to be the hypothalamic arcuate nucleus kisspeptin/neurokinin B/dynorphin A neurons. Agonists of the neurokinin B (NKB) receptor (NK3R) have been shown to suppress the GnRH pulse generator, in a dynorphin A (Dyn)-dependent fashion, under hypoestrogenic conditions, and Dyn has been well documented to mediate several stress-related central regulatory functions. We hypothesized that the NKB/Dyn signaling cascade is required for stress-induced suppression of the GnRH pulse generator. To investigate this ovariectomized rats, iv administered with Escherichia coli lipopolysaccharide (LPS) following intracerebroventricular pretreatment with NK3R or κ-opioid receptor (Dyn receptor) antagonists, were subjected to frequent blood sampling for hormone analysis. Antagonism of NK3R, but not κ-opioid receptor, blocked the suppressive effect of LPS challenge on LH pulse frequency. Neither antagonist affected LPS-induced corticosterone secretion. Hypothalamic arcuate nucleus NKB neurons project to the paraventricular nucleus, the major hypothalamic source of the stress-related neuropeptides CRH and arginine vasopressin (AVP), which have been implicated in the stress-induced suppression of the hypothalamic-pituitary-gonadal axis. A separate group of ovariectomized rats was, therefore, used to address the potential involvement of central CRH and/or AVP signaling in the suppression of LH pulsatility induced by intracerebroventricular administration of a selective NK3R agonist, senktide. Neither AVP nor CRH receptor antagonists affected the senktide-induced suppression of the LH pulse; however, antagonism of type 2 CRH receptors attenuated the accompanying elevation of corticosterone levels. These data indicate that the suppression of the GnRH pulse generator by acute systemic stress requires hypothalamic NKB/NK3R signaling and that any involvement of CRH therewith is functionally upstream of NKB.

Hypothalamic mapping of orexigenic action and Fos-like immunoreactivity following relaxin-3 administration in male Wistar rats

2007 ◽  
Vol 292 (3) ◽  
pp. E913-E919 ◽  
Author(s):  
B. M. McGowan ◽  
S. A. Stanley ◽  
N. E. White ◽  
A. Spangeus ◽  
M. Patterson ◽  
...  
Keyword(s):  
Food Intake ◽  
Supraoptic Nucleus ◽  
Arcuate Nucleus ◽  
Preoptic Area ◽  
Disulphide Bonds ◽  
Hypothalamic Nuclei ◽  
Relaxin Family ◽  
Male Wistar Rats ◽  
Additional Support ◽  
G Protein Coupled

The insulin superfamily, characterized by common disulphide bonds, includes not only insulin but also insulin-like peptides such as relaxin-1 and relaxin-3. The actions of relaxin-3 are largely unknown, but recent work suggests a role in regulation of food intake. Relaxin-3 mRNA is highly expressed in the nucleus incertus, which has extensive projections to the hypothalamus, and relaxin immunoreactivity is present in several hypothalamic nuclei. In the rat, relaxin-3 binds and activates both relaxin family peptide receptor 1, which also binds relaxin-1, and a previously orphaned G protein-coupled receptor, RXFP3. These receptors are extensively expressed in the hypothalamus. The aims of these studies were twofold: 1) map the hypothalamic site(s) of the orexigenic action of relaxin-3 and 2) examine the site(s) of neuronal activation following central relaxin-3 administration. After microinjection into hypothalamic sites, human relaxin-3 (H3; 180 pmol) significantly stimulated 0- to 1-h food intake in the supraoptic nucleus (SON), arcuate nucleus (ARC), and the anterior preoptic area (APOA) [SON 0.4 ± 0.2 (vehicle) vs. 2.9 ± 0.5 g (H3), P < 0.001; ARC 0.7 ± 0.3 (vehicle) vs. 2.7 ± 0.2 g (H3), P < 0.05; and APOA 0.8 ± 0.1 (vehicle) vs. 2.2 ± 0.2 g (H3), P < 0.05]. Cumulative food intake was significantly increased ≤8 h following administration into the SON and 4 h into the APOA. A significant increase in Fos-like immunoreactivity was seen in the SON following central relaxin-3 administration. Relaxin-3 stimulates feeding in several hypothalamic nuclei, and these studies provide additional support for relaxin-3 as an important peptide in appetite regulation.

Histomorphological Studies on the Different Nuclei of Hypothalamus of Indian Buffalo

2020 ◽  
Author(s):  
Devendra Pathak ◽  
Neelam Bansal
Keyword(s):  
Supraoptic Nucleus ◽  
Arcuate Nucleus ◽  
Hypothalamic Nucleus ◽  
Endocrine Gland ◽  
Tissue Samples ◽  
Optic Chiasma ◽  
Cell Groups ◽  
Posterior Hypothalamic Nucleus ◽  
Neurosecretory Substance ◽  
Reproductive Phases

Background: Hypothalamus is an integral part of the hypothalamo-hypophyseal ovarian axis. It contains several small nuclei that have been implicated in several specialized functions. It is the master endocrine gland because it regulates the activity of the pituitary. The present investigation was planned to elucidate the histomorphological details of different nuclei in the hypothalamus of Indian buffaloes. Methods: The hypothalami of buffaloes (n =52) were collected from local abattoirs and Teaching Veterinary Clinical Complex, GADVASU, Ludhiana. The tissue samples were collected from three levels i.e. the supraoptic, tuberal and the mamillary region of the hypothalamus and processed for paraffin sectioning and the sections were stained with various stains for histomorphological studies. Result: The well-defined cell groups or nuclei were identified both in the coronal and sagittal sections of the hypothalamus in all the reproductive phases. Eight nuclei were distinctly recognized in buffalo hypothalamus at three levels in the coronal sections of the hypothalamus. At the level of optic chiasma, the nuclei were paraventricular nucleus (PVN), supraoptic nucleus (SON) and preopticnucleus (PON); at the tuberal region, there were arcuate nucleus (AN) and ventromedial nucleus (VMN) and at the mammillary region, the lateral mammillary nucleus (LMN), medial mammillary nucleus (MMN) and posterior hypothalamic nucleus (PHN) were identified. Most of the nuclei consisted of a loose or compact heterogeneous collection of neurons. The neurons of the different nuclei were of variable shape. The cytoplasm contained a varied amount of Nissl material. The neurosecretory substance was peripheral in position. Small to large-sized blood vessels were observed in between the neuronal substance. The size of the neurons varied during different stages of reproduction.

scholarly journals KNDy Neurons Modulate the Magnitude of the Steroid-Induced Luteinizing Hormone Surges in Ovariectomized Rats

Endocrinology ◽  
2015 ◽  
Vol 156 (11) ◽  
pp. 4200-4213 ◽  
Author(s):  
Cleyde V. Helena ◽  
Natalia Toporikova ◽  
Bruna Kalil ◽  
Andrea M. Stathopoulos ◽  
Veronika V. Pogrebna ◽  
...  
Keyword(s):  
Negative Feedback ◽  
Arcuate Nucleus ◽  
Ovariectomized Rats ◽  
Neurokinin B ◽  
Lh Surge ◽  
Neuronal Populations ◽  
Lh Release ◽  
Positive And Negative Feedback ◽  
Kndy Neurons ◽  
Lh Secretion

Kisspeptin is the most potent stimulator of LH release. There are two kisspeptin neuronal populations in the rodent brain: in the anteroventral periventricular nucleus (AVPV) and in the arcuate nucleus. The arcuate neurons coexpress kisspeptin, neurokinin B, and dynorphin and are called KNDy neurons. Because estradiol increases kisspeptin expression in the AVPV whereas it inhibits KNDy neurons, AVPV and KNDy neurons have been postulated to mediate the positive and negative feedback effects of estradiol on LH secretion, respectively. Yet the role of KNDy neurons during the positive feedback is not clear. In this study, ovariectomized rats were microinjected bilaterally into the arcuate nucleus with a saporin-conjugated neurokinin B receptor agonist for targeted ablation of approximately 70% of KNDy neurons. In oil-treated animals, ablation of KNDy neurons impaired the rise in LH after ovariectomy and kisspeptin content in both populations. In estradiol-treated animals, KNDy ablation did not influence the negative feedback of steroids during the morning. Surprisingly, KNDy ablation increased the steroid-induced LH surges, accompanied by an increase of kisspeptin content in the AVPV. This increase seems to be due to lack of dynorphin input from KNDy neurons to the AVPV as the following: 1) microinjections of a dynorphin antagonist into the AVPV significantly increased the LH surge in estradiol-treated rats, similar to KNDy ablation, and 2) intra-AVPV microinjections of dynorphin in KNDy-ablated rats restored LH surge levels. Our results suggest that KNDy neurons provide inhibition to AVPV kisspeptin neurons through dynorphin and thus regulate the amplitude of the steroid-induced LH surges.

Electrophysiological evidence for a projection from the arcuate nucleus to the supraoptic nucleus

1988 ◽  
Vol 89 (2) ◽  
pp. 146-151 ◽  
Author(s):  
G. Leng ◽  
H. Yamashita ◽  
R.E.J. Dyball ◽  
R. Bunting
Keyword(s):  
Supraoptic Nucleus ◽  
Arcuate Nucleus ◽  
Electrophysiological Evidence

scholarly journals Disparate Changes in Kisspeptin and Neurokinin B Expression in the Arcuate Nucleus After Sex Steroid Manipulation Reveal Differential Regulation of the Two KNDy Peptides in Rats

Endocrinology ◽  
2014 ◽  
Vol 155 (10) ◽  
pp. 3945-3955 ◽  
Author(s):  
Agnete Overgaard ◽  
Francisco Ruiz-Pino ◽  
Juan M. Castellano ◽  
Manuel Tena-Sempere ◽  
Jens D. Mikkelsen
Keyword(s):  
Sex Steroids ◽  
Arcuate Nucleus ◽  
Detailed Examination ◽  
Differential Regulation ◽  
Sex Steroid ◽  
Neurokinin B ◽  
Regulated Expression ◽  
Male Sex ◽  
Specific Regulation ◽  
Kndy Neurons

Abstract Kisspeptin, neurokinin B (NKB) and dynorphin A are coexpressed in a population of neurons in the arcuate nucleus (ARC), termed KNDy neurons, which were recently recognized as important elements for the generation of GnRH pulses. However, the topographic distribution of these peptides and their regulated expression by sex steroids are still not well understood. In this study, detailed examination of NKB and kisspeptin immunoreactivity in the rat ARC was carried out, including comparison between sexes, with and without sex steroid replacement. Neurons expressing kisspeptin and NKB were more prominent in the caudal ARC of females, whereas neurons expressing NKB, but not kisspeptin, were the most abundant in the male. Sex steroid manipulation revealed differential regulation of kisspeptin and NKB; although kisspeptin immunoreactive (ir) cells increased in response to gonadectomy, NKB remained unchanged. Furthermore, the number of NKB-ir cells increased upon sex steroid replacement compared with gonadectomy, whereas kisspeptin did not, suggesting that sex steroids differently regulate these peptides. In addition, only in females did the density of kisspeptin- and NKB-ir fibers in the ARC increase upon sex steroid replacement in relation to sham and ovariectomy, respectively, suggesting sex-specific regulation of release. In conclusion, our observations reveal sex differences in the number of kisspeptin- and NKB-ir cells, which are more prominent in the caudal ARC. The divergent regulation of kisspeptin and NKB peptide contents in the ARC as a function of sex and steroid milieu enlarge our understanding on how these neuropeptides are posttranscriptionally regulated in KNDy neurons.

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