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Ablation of KNDy neurons results in hypogonadotropic hypogonadism and amplifies the steroid-induced LH surge in female rats.
Mittelman-Smith M, Krajewski-Hall S, McMullen N, Rance N (2016) Ablation of KNDy neurons results in hypogonadotropic hypogonadism and amplifies the steroid-induced LH surge in female rats. Endocrinology 157:2015-2027. doi: 10.1210/en.2015-1740
Summary: KNDy neurons are a subpopulation of neurons in the infundibular nucleus that coexpress estrogen receptor α, kisspeptin, and neurokinin B (NKB) mRNA. Previous work indicated that altered signaling from KNDy neurons may play a role in the low levels of circulating sex steroids found in hypogonadotropic hypogonadism. Rats received bilateral 10-ng injections of NK3-SAP (Cat. #IT-63) dorsal to the arcuate nucleus. Blank-SAP (Cat. #IT-21) was used as control. In animals with intact ovaries the NK3-SAP lesion resulted in hypogonadotropic hypogonadism. In contrast, the LH surge in lesioned ovariectomized rats was 3-fold higher, demonstrating that KNDy neurons are integral for the control of serum LH levels, estrous cyclicity, and may also have some control over the magnitude of the LH surge.
Related Products: NKB-SAP (Cat. #IT-63), Blank-SAP (Cat. #IT-21)
KNDy neurons modulate the magnitude of the steroid-induced luteinizing hormone surges in ovariectomized rats.
Helena C, Toporikova N, Kalil B, Stathopoulos A, Pogrebna V, Carolino R, Anselmo-Franci J, Bertram R (2015) KNDy neurons modulate the magnitude of the steroid-induced luteinizing hormone surges in ovariectomized rats. Endocrinology 156:4200-4213. doi: 10.1210/en.2015-1070
Summary: Maturation and reproductive function in mammals is controlled by the kisspeptin neuropeptide. Kisspeptin modulates numerous systems within this framework including the mediation of positive and negative feedback effects of estradiol on luteinizing hormone (LH). In the rat, two kisspeptin neuronal populations exist; one in the anteroventral periventricular nucleus (AVPV), and the KNDy (kisspeptin/ neurokinin B/dynorphin) neurons in the arcuate nucleus. In this work the authors examine the role of KNDy neurons in estradiol positive feedback effects by administering 10-ng bilateral injections of NK3-SAP (Cat. #IT-63) into the arcuate nucleus of rats. The results indicate that KNDy neurons use dynorphin to inhibit AVPV neurons, establishing a regulatory mechanism for the amplitude of steroid-induced LH surges.
Related Products: NKB-SAP (Cat. #IT-63)
Neurokinin 3 receptor-expressing neurons in the median preoptic nucleus modulate heat-dissipation effectors in the female rat.
Mittelman-Smith M, Krajewski-Hall S, McMullen N, Rance N (2015) Neurokinin 3 receptor-expressing neurons in the median preoptic nucleus modulate heat-dissipation effectors in the female rat. Endocrinology 156:2552-2562. doi: 10.1210/en.2014-1974
Summary: Kisspeptin and Neurokinin B (NKB) expression in the infundibular, or arcuate, nucleus is increased after menopause. Here the authors investigate whether KNDy (kisspeptin, NKB, and dynorphin expressing) neurons are able to influence cutaneous vasodilation through Neurokinin 3 (NK3)-expressing projections from the median preoptic nucleus (MnPO). Rats received two 10-ng injections of NK3-SAP (Cat. #IT-63) into the MnPO. Blank-SAP (Cat. #IT-21) was used as a control. The data indicate that NK3-expressing neurons in the MnPO facilitate vasodilation.
Related Products: NKB-SAP (Cat. #IT-63), Blank-SAP (Cat. #IT-21)
Involvement of kndy neurons in luteinizing hormone surges induced by steroids
Helena CV, Toporikova N, Kalil B, Stathopoulos AM, Anselmo-Franci JA, Bertram R (2014) Involvement of kndy neurons in luteinizing hormone surges induced by steroids. Neuroscience 2014 Abstracts 543.11. Society for Neuroscience, Washington, DC.
Summary: A subset of hypothalamic arcuate neurons that coexpress kisspeptin, neurokinin B and dynorphin (KNDy neurons) has been postulated to be critical for puberty onset and regulation of luteinizing hormone (LH) secretion. A method for targeted ablation of KNDy neurons was recently developed using the molecular neurotoxin saporin conjugated to the selective NK3R agonist [MePhe7]Neurokinin B (Nk3-SAP). Ovariectomized rats were microinjected bilaterally into the arcuate nucleus with Blank-SAP or Nk3-SAP. One set of rats was transcardiacally perfused 1, 2 or 3 weeks after the injections and immunocytochemistry for kisspeptin was performed in the arcuate nucleus region. The number of KNDy neurons was significantly decreased after 1 week of the toxin injection, however maximal fiber ablation was only achieved 3 weeks after the microinjections. Another group of rats was treated with oil (OVO), estradiol (OVE) or estradiol plus progesterone (OVEP). One week later, rats had their jugular vein cannulated and blood samples were taken at 10am and hourly from 3 until 6pm. Selective ablation of KNDy neurons of OVO rats significantly reduced basal LH levels at all time points studied. Basal LH levels in OVE and OVEP animals did not differ between groups, yet KNDy ablation increased peak LH levels in the afternoon of OVE and OVEP rats. A third group of OVE animals was microinjected with norbinaltorphimine (nor-BNI), a kappa opioid receptor antagonist, directly into the anteroventral periventricular nucleus (AVPV) one hour before the expected LH surge. The blockage of dynorphin receptors intra-AVPV significantly increased the LH surge, similar to the effect of KNDy ablation in OVE rats. Our results suggest that KNDy neurons provide inhibition to AVPV kisspeptin neurons through dynorphin and thus regulate the size of the LH surge induced by estradiol or estradiol plus progesterone.
Related Products: NKB-SAP (Cat. #IT-63)
Habenular kisspeptin modulates fear in the zebrafish.
Ogawa S, Nathan FM, Parhar IS (2014) Habenular kisspeptin modulates fear in the zebrafish. Proc Natl Acad Sci U S A 111(10):3841-3846. doi: 10.1073/pnas.1314184111
Summary: The peptide kisspeptin can be found in several areas of the brain, but its role in regions other than the hypothalamus has not been studied. Zebrafish express kiss1 mRNA which is a conserved ortholog of the mammalian KISSI/KissI making zebrafish a viable model for investigating the role of kisspeptin in various brain systems. Animals received 1 μg of the custom conjugate kiss-SAP (see NK3-SAP, Cat. #IT-63) via an intracranial injection. Blank-SAP (Cat. #IT-21) was used as a control. Reducing Kiss1 immunoreactivity in the habenula and the raphe reduced an invoked fear response, indicating a role for kisspeptin in fear inhibition.
Related Products: Blank-SAP (Cat. #IT-21), NKB-SAP (Cat. #IT-63), Custom Conjugates
Ablation of arcuate KNDy neurons amplifies the LH surge in steroid-primed, ovariectomized rats.
Krajewski-Hall SJ, Mittelman-Smith, Mcmullen NT, Rance NE (2013) Ablation of arcuate KNDy neurons amplifies the LH surge in steroid-primed, ovariectomized rats. Neuroscience 2013 Abstracts 274.01. Society for Neuroscience, San Diego, CA.
Summary: KNDy (kisspeptin, neurokinin B and dynorphin) neurons in the arcuate nucleus play an important role in the reproductive axis. We have developed a method to selectively ablate KNDy neurons in the rat using NK3-SAP, a neurokinin 3 receptor agonist conjugated to saporin (Mittelman-Smith, Endocrinology 2012). Ablation of KNDy neurons results in cessation of estrous cycles, ovarian atrophy, a decrease in tonic LH secretion and loss of the rise of serum LH after ovariectomy. Given these profound effects, we tested if we could induce an LH surge in KNDy-ablated rats using a well-established steroid replacement regimen. Rats were maintained on a 14:10 light cycle (lights on at 0500). Using stereotactic surgery, NK3-SAP or Blank-SAP was injected in the arcuate nucleus and rats were allowed to recover for one month before ovariectomy. Seven days after ovariectomy they were implanted with silastic capsules containing 17β-estradiol. Two days later, they were implanted with progesterone capsules (~0830h). Rats were sacrificed in the afternoon at a time previously shown to exhibit peak LH surge levels (~1600h) and the brains were processed for immunohistochemistry. Ablation of KNDy neurons was verified by near complete loss of NKB-immunoreactive neurons in the arcuate nucleus in NK3-SAP rats. At 0830h, tonic levels of serum LH were significantly lower in KNDy ablated rats, consistent with our previous studies. Unexpectedly, the surge in serum LH at 1600h was more than 3-fold higher in NK3-SAP-treated rats compared to Blank-SAP controls (53.5 + 16.5 ng/ml vs 16.5 + 2.1 ng/ml, respectively). To determine if this change was associated with increased activation of GnRH neurons, dual-labeled GnRH-fos immunocytochemistry was performed in rostral hypothalamic sections. There was no significant difference in the total number of GnRH cells counted in 4 matched sections (NK3-SAP, 85.8 + 9.8 vs Blank-SAP, 84.9 + 4.6) or in the percentage of GnRH cells that were activated, as measured by GnRH-fos coexpression (NK3-SAP, 22.4 + 1.8% vs Blank-SAP, 16.6 + 4.9%). In addition, there was no difference between NK3-SAP and Blank-SAP controls in the number of fos-ir cells counted in the AVPV. These data indicate that arcuate KNDy neurons are not required for the induction of an LH surge. The marked increase in the LH surge in KNDy-ablated rats, however, suggests that KNDy neurons are important for regulating the magnitude of the surge.
Related Products: NKB-SAP (Cat. #IT-63)
Time course study of targeted ablation of KNDy neurons, but not tyrosine-hydroxylase neurons, in the rat arcuate nucleus using a neurokinin b-saporin.
Helena CV, Kalil B, Anselmo-Franci JA, Bertram R (2013) Time course study of targeted ablation of KNDy neurons, but not tyrosine-hydroxylase neurons, in the rat arcuate nucleus using a neurokinin b-saporin. Endocr Rev 34:OR47-5. 95th Annual Meetin and Expo, San Francisco. doi: 10.1093/edrv/34.supp.1
Summary: Ovariectomized rats were given bilateral injections of NK3-SAP (Cat. #IT-63) into the arcuate nucleus for a time course study of KNDy neuron loss. Blank-SAP (Cat. #IT-21) was used as a control.
Related Products: NKB-SAP (Cat. #IT-63), Blank-SAP (Cat. #IT-21)
Role for kisspeptin/neurokinin B/dynorphin (KNDy) neurons in cutaneous vasodilatation and the estrogen modulation of body temperature.
Mittelman-Smith MA, Williams H, Krajewski-Hall SJ, McMullen NT, Rance NE (2012) Role for kisspeptin/neurokinin B/dynorphin (KNDy) neurons in cutaneous vasodilatation and the estrogen modulation of body temperature. Proc Natl Acad Sci U S A 109(48):19846-19851. doi: 10.1073/pnas.1211517109
Summary: Menopause is marked by estrogen withdrawal, and also by hot flushes. Given the fact that hypothalamic levels of kisspeptin/neurokinin B/dynorphin (KNDy) neurons are significantly altered in menopause, the authors investigated whether these neurons are involved in the generation of flushes. Rats received bilateral injections of NK3-SAP (Cat. #IT-63) into the arcuate nucleus – a total of 40 ng. Blank-SAP (Cat. #IT-21) was used as control. The data indicate that KNDy neurons promote cutaneous vasodilation, and play a role in 17β-estradiol modulation of body temperature, supporting the hypothesis that these neurons could play a role in the generation of hot flushes.
Related Products: NKB-SAP (Cat. #IT-63), Blank-SAP (Cat. #IT-21)
A role for kisspeptin/neurokinin B/dynorphin (KNDy) neurons in the regulation of estrous cycles and the estrogen modulation of body temperature.
Krajewski-Hall SJ, Mittelman-Smith MA, Williams H, Lafrance KJ, Mcmullen NT, Rance NE (2012) A role for kisspeptin/neurokinin B/dynorphin (KNDy) neurons in the regulation of estrous cycles and the estrogen modulation of body temperature. Neuroscience 2012 Abstracts 585.02. Society for Neuroscience, New Orleans, LA.
Summary: We have recently described a method to selectively ablate kisspeptin/neurokinin B/dynorphin (KNDy) neurons using stereotaxic injections of NK3-SAP, a neurokinin 3 receptor agonist conjugated to saporin (Mittelman-Smith, Endocrinology, 2012). These studies revealed a critical role for arcuate KNDy neurons in tonic gonadotropin secretion, the rise in serum LH after ovariectomy and estrogen modulation of body weight. Here we determine the effects of KNDy neuron ablation on estrous cycles and the estradiol modulation of body temperature. In the first study, stereotaxic injections of NK3-SAP or Blank-SAP were made in the arcuate nucleus of ovary-intact, adult female rats. Rats with nearly complete KNDy-neuron ablation (verified by NKB immunohistochemistry) exhibited constant diestrus and ovarian atrophy, confirming the importance of these neurons in reproductive regulation. In a second experiment, we evaluated the effects of KNDy neuron ablation on the thermoregulatory axis in rats that were ovariectomized (OVX) and then treated with 17β-estradiol (E2). Tail skin temperatures (TSKIN) and core temperatures (TCORE) were recorded in rats throughout the light/dark cycle and during exposure to different ambient temperatures (TAMBIENT) in an environmental chamber. Notably, the average TSKIN of KNDy-ablated rats was consistently lower than control rats, indicative of lower levels of cutaneous vasodilatation. Moreover, KNDy neuron ablation blocked the reduction of TSKIN by E2 that occurred during the light phase in the environmental chamber, but did not affect the E2 suppression of TSKIN during the dark phase. At a high TAMBIENT of 33 C, the mean TCORE of OVX control rats increased to 39.0 C, and was reduced by E2 replacement. In contrast, at this high TAMBIENT, the average TCORE of OVX, KNDy-ablated rats was lower than OVX control rats, and TCORE was not altered by E2 replacement. Because KNDy neurons exhibit dramatic changes in morphology and gene expression in postmenopausal women, we have hypothesized these neurons contribute to the generation of hot flushes. These studies support this hypothesis by providing the first evidence that KNDy neurons participate in the E2 modulation of body temperature and promote cutaneous vasodilatation, one of the cardinal signs of a hot flush.
Related Products: NKB-SAP (Cat. #IT-63), Blank-SAP (Cat. #IT-21)
Arcuate kisspeptin/neurokinin b/dynorphin (KNDy) neurons mediate the estrogen suppression of gonadotropin secretion and body weight.
Mittelman-Smith MA, Williams H, Krajewski-Hall SJ, Lai J, Ciofi P, McMullen NT, Rance NE ( 2012 ) Arcuate kisspeptin/neurokinin b/dynorphin (KNDy) neurons mediate the estrogen suppression of gonadotropin secretion and body weight. Endocrinology 153(6):2800-2812 . doi: 10.1210/en.2012-1045
Related Products: NKB-SAP (Cat. #IT-63), Blank-SAP (Cat. #IT-21)