Aerts EG, Griesgraber MJ, Shuping SL, Bowdridge EC, Hardy SL, Goodman RL, Nestor CC, Hileman SM (2024) The effect of NK3-Saporin injection within the arcuate nucleus on puberty, the LH surge, and the response to Senktide in female sheep. Biol Reprod 110(2):275-287. doi: 10.1093/biolre/ioad147 PMID: 37930247

Objective: To investigate the role of NKB-SAP (NK3-SAP) in the arcuate nucleus on the timing of puberty, the LH surge, and the response to the NK3R agonist senktide in female sheep.

Summary: This study explores how the ablation of NK3R-containing neurons in the arcuate nucleus affects puberty onset and reproductive hormone dynamics in female sheep. The findings demonstrate that NK3-SAP injections significantly delay puberty, reduce the amplitude of the LH surge, and alter the response to senktide, underscoring the critical role of NK3R-containing neurons in reproductive function.

Usage: Prepubertal ewes received 1 μL (0.7 μg) of NKB-SAP (NK3-SAP) [IT-63] or Blank-SAP (IT-21) injections aimed at the arcuate (ARC) nucleus to ablate neurons expressing NK3R.

Related Products: NKB-SAP (Cat. #IT-63), Blank-SAP (Cat. #IT-21)

Ivanova D, O’Byrne KT (2024) New methods to investigate the GnRH pulse generator. J Mol Endocrinol 72(2):e230079. doi: 10.1530/JME-23-0079 PMID: 38085702

Objective: To review the latest methodologies and insights into the GnRH pulse generator and its role in regulating reproductive hormone secretion.

Summary: The paper discusses recent advancements in understanding the GnRH pulse generator and its role in reproductive hormone secretion. It highlights the involvement of kisspeptin/neurokinin B/dynorphin (KNDy) neurons and the use of advanced techniques like genetic mouse models, electrophysiology, optogenetics, and calcium imaging. These findings enhance our comprehension of the KNDy network’s oscillatory behavior and its regulation by gonadal steroids, which is crucial for developing better infertility treatments.

Related Products: NKB-SAP (Cat. #IT-63)

See Also:

• Helena C et al. KNDy neurons modulate the magnitude of the steroid-induced luteinizing hormone surges in ovariectomized rats. Endocrinology 156:4200-4213, 2015.

Campideli-Santana AC, da Costa Silva KS, Araújo-Lopes R, Antunes LM, Szawka RE (2023) Submaximal loss of KNDy neurons accelerates and amplifies pulsatile LH secretion in female rats. J Endocrine Society 7(S1):bvad114.1214. doi: 10.1210/jendso/bvad114.1214

Objective: To investigate the impact of the submaximal loss of KNDy neurons on the pulsatile secretion of luteinizing hormone (LH) in female rats.

Summary: The study found that a partial loss of these neurons led to irregular estrous cycles and increased frequency and amplitude of LH pulses. This suggests a new role for KNDy neurons in moderating LH pulse frequency and amplitude in ovary-intact animals, with implications for early antral follicle recruitment.

Usage: Adult female rats underwent a neurochemical ablation of KNDy neurons via intra-ARC stereotaxic injections of NKB-SAP (IT-63), while control animals received Blank-SAP (IT-21).

Related Products: NKB-SAP (Cat. #IT-63), Blank-SAP (Cat. #IT-21)

Aquino NSS, Campideli-Santana AC, Antunes LM, Araújo-Lopes R, da Costa Silva KS, Costa Henriques P, de Oliveira Gusmão D, Bernuci MP, Szawka RE, dos Reis AM (2023) Partial loss of KNDy neurons in prenatally androgen treated female rats alters the LH secretion and ovarian morphology in a model of polycystic ovary syndrome. J Endocrine Society 7(S1):bvad114.1215. doi: 10.1210/jendso/bvad114.1215

Objective: To examine the impact of partial loss of KNDy neurons in prenatally androgen-treated female rats on luteinizing hormone (LH) secretion and ovarian morphology, as a model of polycystic ovary syndrome (PCOS).

Summary: The study found that the ablation of KNDy neurons resulted in increased LH pulse amplitude and mean LH levels without affecting pulse frequency, and partially restored the number of primordial follicles, suggesting KNDy neurons’ role in modulating LH release and ovarian reserve in PCOS.

Usage: Intra-ARC stereotaxic injections of the neurokinin-3 receptor agonist conjugated with Saporin (NKB-SAP, IT-63) to induce the lesion of KNDy neurons. Blank-SAP (IT-21) was used as a control.

Related Products: NKB-SAP (Cat. #IT-63), Blank-SAP (Cat. #IT-21)

Goodman RL, Moore AM, Onslow K, Hileman SM, Hardy SL, Bowdridge EC, Walters BA, Agus S, Griesgraber MJ, Aerts EG, Lehman MN, Coolen LM (2023) Lesions of kndy and kiss1r neurons in the arcuate nucleus produce different effects on lh pulse patterns in female sheep. Endocrinology 164(11):bqad148. doi: 10.1210/endocr/bqad148 PMID: 37776515

Objective: To test the functional role of ovine KNDy neurons in pulse generation and identify the roles of nearby Kiss1 receptor (Kiss1R)-containing cells.

Summary: Injection of NK3-SAP (NKB-SAP) ablated over 90% of the KNDy cells, Kiss-SAP lesioned about two-thirds of the Kiss1R population. This led to a significant decrease in LH pulse amplitude and altering LH pulse patterns. NK3-SAP increased the interpulse interval without affecting the regularity of LH pulses, whereas Kiss-SAP disrupted their regular hourly occurrence but not the interpulse interval. The findings suggest that KNDy neurons are critical for GnRH pulse generation in ewes, while ARC Kiss1R cells support the amplitude and regularity of these pulses, possibly as part of a positive feedback loop involving GABA or glutamate.

Usage: Saporin conjugates were injected into the arcuate nucleus. Kiss-SAP (kisspeptin54-SAP) was diluted to 700 ng/μL in PBS immediately before use. In preliminary work to test the effectiveness of Kiss-SAP, a single unilateral injection (1 μL of 700 ng/μL) of this conjugate was made in the preoptic area of 3 ewes. The contralateral side was used as control and either received no injections or Blank-SAP (1 μL of 700 ng/μL) (IT-21).

Related Products: NKB-SAP (Cat. #IT-63), Blank-SAP (Cat. #IT-21)

Nestor CC, Merkley CM, Lehman MN, Hileman SM, Goodman RL (2023) KNDy neurons as the GnRH pulse generator: Recent studies in ruminants. Peptides 164:171005. doi: 10.1016/j.peptides.2023.171005 PMID: 36990389

Objective: This publication aims to summarize and provide an overview of recent studies investigating the role of KNDy neurons as the pulse generator for gonadotropin-releasing hormone (GnRH) release in ruminants.

Summary: Recent studies in ruminants, specifically sheep and cows, have investigated the role of KNDy neurons in driving the pulsatile release of GnRH. These studies have demonstrated the rhythmic electrical activity of KNDy neurons, coinciding with the pulsatile secretion of GnRH in ewes, suggesting their central role as the pulse generator. Additionally, the expression patterns of genes related to KNDy neurons and GnRH pulsatility have been examined in cows, revealing variations throughout the estrous cycle and indicating a potential involvement of KNDy neurons in regulating GnRH release in this species. These findings contribute to our understanding of reproductive physiology in ruminants and have implications for both animal and human reproductive health.

Related Products: NKB-SAP (Cat. #IT-63)

Goodman RL, He W, Lopez JA, Bedenbaugh MN, McCosh RB, Bowdridge EC, Coolen LM, Lehman MN, Hileman SM (2019) Evidence that the LH surge in ewes involves both neurokinin B–dependent and –independent actions of kisspeptin. Endocrinology 160(12):2990-3000. doi: 10.1210/en.2019-00597

Objective: To determine if NKB is involved in the RCh of the ewe in the LH surge.

Summary: NKB signaling in the RCh increases kisspeptin levels critical for the full amplitude of the LH surge in the ewe, but kisspeptin release occurs independently of retrochiamatic area (RCh) input at the onset of the surge to initiate GnRH secretion.

Usage: Bilaterial injections in the RCh of either NK3-SAP or Blank-SAP.

Related Products: NKB-SAP (Cat. #IT-63), Blank-SAP (Cat. #IT-21)

Sakata D, Uruno T, Matsubara K, Andoh T, Yamamura K, Magoshi Y, Kunimura K, Kamikaseda Y, Furue M, Fukui Y (2019) Selective role of neurokinin B in IL-31–induced itch response in mice. J Allergy Clin Immunol 144(4):1130-1133. doi: 10.1016/j.jaci.2019.06.031

Objective: To examine the physiological significance of neurokinin B in IL-31–induced itch sensation.

Summary: IL-31–induced scratching was unaffected by intrathecal injection of Nppb-SAP. In contrast,treatment with Bombesin-SAP reduced IL-31–induced scratching. Neurokinin B acts upstream of GRP to transmit IL-31–induced itch sensation.

Usage: Intrathecal injection

Related Products: Bombesin-SAP (Cat. #IT-40), Nppb-SAP (Cat. #IT-69), Blank-SAP (Cat. #IT-21), NKB-SAP (Cat. #IT-63)

Krajewski-Hall SJ, Miranda Dos Santos F, McMullen NT, Blackmore EM, Rance NE (2019) Glutamatergic neurokinin 3 receptor neurons in the median preoptic nucleus modulate heat-defense pathways in female mice. Endocrinology 160(4):803-816. doi: 10.1210/en.2018-00934

Objective: To characterize the thermoregulatory role of MnPO NK3R neurons in female mice.

Summary: Study suggests that KNDy neurons modulate thermosensory pathways for heat defense indirectly via a subpopulation of glutamatergic MnPO neurons that express NK3R.

Usage: Mice were bilaterally injected with 10 ng NK3-SAP in 100 nL PBS (n = 14) or blank-SAP (n = 8) in the preoptic area adjacent to the MnPO.

Related Products: NKB-SAP (Cat. #IT-63), Blank-SAP (Cat. #IT-21)

Goodman RL, Lopez JA, Bedenbaugh MN, Connors JM, Hardy SL< Hileman SM, Coolen LM, Lehman MN (2018) Evidence that the LH surge in ewes involves both neurokinin B-dependent and -independent actions of kisspeptin. Neuroscience 2018 Abstracts 773.20 / YY14. Society for Neuroscience, San Diego, CA.

Summary: It is generally recognized that kisspeptin plays a key role in induction of the LH surge in sheep and we have reported evidence that neurokinin B (NKB) does so as well. Specifically, disrupting NKB signaling in the retrochiasmatic area (RCh) using either an antagonist to its receptor, NK3R, or lesions of NK3R-containing neurons in the RCh with a saporin conjugate (NK3-SAP) reduced the amplitude of the estrogen-induced LH surge by 50%. Because a KISS1R antagonist (p271) also produced a 50% decrease in surge amplitude, we hypothesized that these two systems are organized in series with NKB actions in the RCh stimulating kisspeptin release. If this is the case, then the combination of NK3R lesions and a KISS1R antagonist should produce the same inhibition as either treatment alone. This experiment tested this prediction using a 2 x 2 design. Breeding season ewes were ovariectomized and immediately given an estradiol (E) implant sc and two progesterone implants (CIDRs) intravaginally that produced luteal phase levels of these steroids. Ewes then received bilateral injections of either NK3-SAP (n=6) or Blank-SAP (n=5) into the RCh. Three weeks later, an artificial follicular phase was produced by inserting four 3 cm long E implants 24 hrs after CIDR removal and either saline or p271 was infused into the lateral ventricle for 16-24 hrs after E implantation; LH was monitored every 2-4 hrs for two days. CIDRs were then reinserted and the protocol repeated in a cross-over design so that all ewes received saline and p271 treatment. In Blank-SAP ewes, p271 decreased the peak of the LH surge from 61.2 ± 7.6 to 27.4 ± 4.6 ng/mL and delayed it 8 hrs (from 26.5 ± 0.5 to 34.1 ± 1.2 hrs post E implantation). The NK3-SAP injections alone decreased the peak of the LH surge to 29.7 ± 10.7 ng/mL compared to Blank-SAP, but the peak was not further inhibited by p271 in these NK3-SAP-treated ewes (24.4 ± 1.4 ng/mL). However, p271 delayed the peak of the LH surge (from 28.8 ± 1.2 to 34.8 ± 2.1 hrs post E implantation) in the ewes injected with NK3-SAP. Based on these results, we propose that kisspeptin has two roles in the LH surge in ewes: it initiates the surge independent of NKB signaling in the RCh, and maintains LH secretion during the surge by a NKB-dependent system.

Related Products: NKB-SAP (Cat. #IT-63), Blank-SAP (Cat. #IT-21), Custom Conjugates