scholarly journals Neurokinin 3 Receptor Immunoreactivity in the Septal Region, Preoptic Area and Hypothalamus of the Female Sheep: Colocalisation in Neurokinin B Cells of the Arcuate Nucleus but not in Gonadotrophin-Releasing Hormone Neurones

2010 ◽  
Vol 22 (1) ◽  
pp. 1-12 ◽  
Author(s):  
M. Amstalden ◽  
L. M. Coolen ◽  
A. M. Hemmerle ◽  
H. J. Billings ◽  
J. M. Connors ◽  
...  
Keyword(s):  
B Cells ◽  
Arcuate Nucleus ◽  
Preoptic Area ◽  
Neurokinin B ◽  
Releasing Hormone ◽  
Septal Region ◽  
Gonadotrophin Releasing Hormone ◽  
Neurokinin 3 Receptor ◽  
Female Sheep

scholarly journals Prenatal Testosterone Treatment Leads to Changes in the Morphology of KNDy Neurons, Their Inputs, and Projections to GnRH Cells in Female Sheep

Endocrinology ◽  
2015 ◽  
Vol 156 (9) ◽  
pp. 3277-3291 ◽  
Author(s):  
Maria Cernea ◽  
Vasantha Padmanabhan ◽  
Robert L. Goodman ◽  
Lique M. Coolen ◽  
Michael N. Lehman
Keyword(s):  
Feedback Control ◽  
Arcuate Nucleus ◽  
Preoptic Area ◽  
Neurokinin B ◽  
Medial Basal Hypothalamus ◽  
Synaptic Inputs ◽  
Prenatal Testosterone ◽  
Peptide Expression ◽  
Kndy Neurons ◽  
Female Sheep

Prenatal testosterone (T)-treated ewes display a constellation of reproductive defects that closely mirror those seen in PCOS women, including altered hormonal feedback control of GnRH. Kisspeptin/neurokinin B/dynorphin (KNDy) neurons of the arcuate nucleus (ARC) play a key role in steroid feedback control of GnRH secretion, and prenatal T treatment in sheep causes an imbalance of KNDy peptide expression within the ARC. In the present study, we tested the hypothesis that prenatal T exposure, in addition to altering KNDy peptides, leads to changes in the morphology and synaptic inputs of this population, kisspeptin cells of the preoptic area (POA), and GnRH cells. Prenatal T treatment significantly increased the size of KNDy cell somas, whereas POA kisspeptin, GnRH, agouti-related peptide, and proopiomelanocortin neurons were each unchanged in size. Prenatal T treatment also significantly reduced the total number of synaptic inputs onto KNDy neurons and POA kisspeptin neurons; for KNDy neurons, the decrease was partly due to a decrease in KNDy-KNDy synapses, whereas KNDy inputs to POA kisspeptin cells were unaltered. Finally, prenatal T reduced the total number of inputs to GnRH cells in both the POA and medial basal hypothalamus, and this change was in part due to a decreased number of inputs from KNDy neurons. The hypertrophy of KNDy cells in prenatal T sheep resembles that seen in ARC kisspeptin cells of postmenopausal women, and together with changes in their synaptic inputs and projections to GnRH neurons, may contribute to defects in steroidal control of GnRH observed in this animal model.

scholarly journals Evidence of a Role for Kisspeptin and Neurokinin B in Puberty of Female Sheep

Endocrinology ◽  
2012 ◽  
Vol 153 (6) ◽  
pp. 2756-2765 ◽  
Author(s):  
Casey C Nestor ◽  
Amanda M.S. Briscoe ◽  
Shay M. Davis ◽  
Miro Valent ◽  
Robert L. Goodman ◽  
...  
Keyword(s):  
Arcuate Nucleus ◽  
Preoptic Area ◽  
Age Groups ◽  
Neurokinin B ◽  
Genetic Studies ◽  
Cell Numbers ◽  
Puberty Onset ◽  
Lh Secretion ◽  
Female Sheep ◽  
Close Contacts

Puberty onset in female sheep is marked by a decrease in estradiol-negative feedback, allowing for the increase in GnRH and LH pulses that heralds the first ovulation. Based on recent genetic studies in humans, two possible neuropeptides that could promote puberty onset are kisspeptin and neurokinin B (NKB). Our first experiment determined whether the NKB agonist, senktide, could stimulate LH secretion in prepubertal ewes. A second study used prepubertal and postpubertal ewes that were intact or ovariectomized (OVX) to test the hypothesis that expression of kisspeptin and NKB in the arcuate nucleus increased postpubertally. For comparison, kisspeptin and NKB expression in age-matched intact, and castrated males were also examined. In experiment 1, the percentage of ewes showing an LH pulse immediately after injection of senktide (100 μg, 60%; 500 μg, 100%) was greater than that for water-injected controls (experiment 1a, 25%; experiment 1b, 20%). In experiment 2, kisspeptin-positive cell numbers in the arcuate nucleus increased after puberty in intact females and were increased by OVX in prepubertal but not postpubertal ewes. Changes in kisspeptin cell numbers were paralleled by changes in kisspeptin-close contacts onto GnRH neurons in the medial preoptic area. NKB cell numbers did not differ significantly between intact prepubertal and postpubertal ewes but increased with OVX in both age groups. NKB fiber immunoreactivity was greater in postpubertal than in prepubertal intact ewes. In age-matched males, kisspeptin and NKB cell numbers increased with castration, but decreased with age. These results support the hypothesis that kisspeptin is a gatekeeper to female ovine puberty and raise the possibility that NKB may also play a role, albeit through different means.

scholarly journals Arcuate nucleus kisspeptin response to increased nutrition in rams

2019 ◽  
Vol 31 (11) ◽  
pp. 1682 ◽  
Author(s):  
S. E. Rietema ◽  
P. A. R. Hawken ◽  
C. J. Scott ◽  
M. N. Lehman ◽  
G. B. Martin ◽  
...  
Keyword(s):  
Arcuate Nucleus ◽  
Preoptic Area ◽  
Pulse Generator ◽  
Pulse Frequency ◽  
Nutritional Supplementation ◽  
Environmental Cues ◽  
Dorsomedial Hypothalamus ◽  
Gonadotrophin Releasing Hormone ◽  
Kndy Neurons

Rams respond to acute nutritional supplementation by increasing the frequency of gonadotrophin-releasing hormone (GnRH) pulses. Kisspeptin neurons may mediate the effect of environmental cues on GnRH secretion, so we tested whether the ram response to nutrition involves activation of kisspeptin neurons in the arcuate nucleus (ARC), namely kisspeptin, neurokin B, dynorphin (KNDy) neurons. Rams were given extra lupin grain with their normal ration. Blood was sampled before feeding, and continued until animals were killed for collection of brain tissue at 2 or 11h after supplementation. In supplemented rams, LH pulse frequency increased after feeding, whereas control animals showed no change. Within the caudal ARC, there were more kisspeptin neurons in supplemented rams than in controls and a higher proportion of kisspeptin cells coexpressed Fos, regardless of the time the rams were killed. There were more Fos cells in the mid-ARC and mid-dorsomedial hypothalamus of the supplemented compared with control rams. No effect of nutrition was found on kisspeptin expression in the rostral or mid-ARC, or on GnRH expression in the preoptic area. Kisspeptin neurons in the caudal ARC appear to mediate the increase in GnRH and LH production due to acute nutritional supplementation, supporting the hypothesised role of the KNDy neurons as the pulse generator for GnRH.

Patterns of preoptic–hypothalamic neuronal activation and LH secretion in female sheep following the introduction and withdrawal of novel males

2019 ◽  
Vol 31 (11) ◽  
pp. 1674
Author(s):  
Penny A. R. Hawken ◽  
Jeremy T. Smith ◽  
Trina Jorre de St Jorre ◽  
Tammi Esmaili ◽  
Christopher J. Scott ◽  
...  
Keyword(s):  
Neural Activity ◽  
Arcuate Nucleus ◽  
Preoptic Area ◽  
Ventromedial Nucleus ◽  
Neural Activation ◽  
Lamina Terminalis ◽  
Neuronal Activation ◽  
Neuroendocrine Response ◽  
Lh Secretion ◽  
Female Sheep

The neuroendocrine response of female sheep to a novel male involves neural activation in the hypothalamus. However, if males are removed, the gonadotrophic signal declines, so the neural activity is likely to change. We examined Fos-immunoreactive (IR) cells in hypothalamic tissues from seasonally anovulatory female sheep exposed to males for 2 or 6h, or for 2h followed by 4h isolation from males. Control females were killed in the absence of male exposure. Male introduction increased LH secretion in all females; male removal was associated with a reduction only in mean and basal LH concentrations. Females exposed to males for 2h had more Fos-IR cells in the arcuate nucleus (ARC), ventromedial nucleus of the hypothalamus (VMH) and organum vasculosum of the lamina terminalis (OVLT) than control females. Fos-IR cells in the preoptic area (POA) were only greater than in control females after 6h exposure to a male. Removal of males decreased the number of Fos-IR cells in the ARC, VMH and OVLT, but not in the POA. Thus, hypothalamic neural activation and LH secretion in female sheep are stimulated by males and decline after male removal. However, activation in the POA persists after removal and may explain the incomplete decline in the LH response.

329. IS THERE VARIATION IN THE LEVEL OF INPUT OF KISSPEPTIN TERMINALS ONTO GnRH NEURONS ACROSS THE EQUINE OESTROUS CYCLE?

2010 ◽  
Vol 22 (9) ◽  
pp. 129
Author(s):  
C. J. Scott ◽  
C. A. Setterfield ◽  
A. Caraty ◽  
S. T. Norman
Keyword(s):  
Arcuate Nucleus ◽  
Preoptic Area ◽  
Reproductive Function ◽  
Oestrous Cycle ◽  
Gnrh Neurons ◽  
Gonadotrophin Releasing Hormone ◽  
Potential Interactions ◽  
Lh Secretion ◽  
The Brain ◽  
Dual Label

Kisspeptin (KP) plays a key role in reproductive function including the regulation of gonadotrophin releasing hormone (GnRH) and luteinising hormone (LH) secretion in many species but little is known about its role in the mare. In this study, we examined the location of KP-producing neurons in the brain of the mare, their potential interactions with GnRH neurons, and temporal changes in their expression across the oestrous cycle. Mares (n = 3/group) were killed at oestrus (just prior to ovulation), mid-dioestrus, and late dioestrus and the head was perfusion fixed with paraformaldehyde, and hypothalamus collected. Coronal sections (40 μm) were used for dual-label immuno-stained for KP & GnRH. The majority of KP-immunoreactive (-ir) neurons were located in the arcuate nucleus/median eminence (especially mid and caudal regions), and periventricular nucleus. There was a trend (P = 0.09) towards increasing numbers of KP-ir neurons across the cycle. GnRH-ir neurons, located primarily in the arcuate nucleus (especially mid arcuate), as well as the preoptic area, did not change in number across the cycle. Numerous interactions between KP and GnRH neurons were observed, primarily in the arcuate nucleus; KP fibres interacting with GnRH cell bodies, fibre-fibre interactions between KP and GnRH, and GnRH fibres interacting with KP cell bodies. Overall we found KP inputs to 32% of GnRH-ir cells, but the number of these interactions did not vary across the oestrous cycle. This study has confirmed the reciprocal innervation between KP & GnRH neurons in the mare. Although we did not detect variation in the degree across the oestrous cycle this may reflect the sample size issues inherent to equine research.

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