Inhibitory effects of central neuropeptide Y on the somatotropic and gonadotropic axes in male rats are independent of adrenal hormones

Introduction: The neuropeptide Y (NPY) in the neural circuits of the hypothalamus has a stimulating effect on reproductive activities in mammals. Kisspeptin (KiSS1) is a quintessential neurotransmitter in the reproductive axis which directly stimulates gonadotropin-releasing hormone neurons in the hypothalamus. The distribution of KiSS1 expressing cells in the pituitary was described previously. Despite earlier reports showing the KiSS1 receptor, G-protein coupled receptor 54 (GPR54) expression in the pituitary, the potential physiological roles of kisspeptin at this gland have remained obscure. Accordingly, this study investigated the role of NPY on the relative expression of Kiss1 and Gpr54 genes in the pituitary gland in male Wistar rats. Methods: In general, 20 male Wistar rats weighing 200-250 g in 4 groups (5 in each group) received saline, NPY (2.3 nM), BIBP3226 (NPY receptor antagonist, 7.8 nM), and NPY+ BIBP3226. Then, they received the simultaneous injection of these molecules through the third ventricle of the brain. Finally, the relative mean expressions of Kiss1 and Gpr54 genes in the anterior pituitary were quantitatively analyzed by the real-time polymerase chain reaction. Results: The central injection of NPY increased the relative mean expressions of Kiss1 and Gpr54 genes in the pituitary gland compared to the control group although the injection of BIBP3226 eradicated these effects. However, the gene expression of Gpr54 in the rats receiving NPY coupled with BIBP3226 in hypophysis in comparison to the group receiving only NPY demonstrated a significant reduction (P<0.05). Conclusion: Overall, the central injection of NPY stimulated the gene expression of Kiss1 and Gpr54 in the pituitary gland.

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Neuropeptide Y and Galanin Enhance the Inhibitory Effects of Clonidine on Norepinephrine Release From Medulla Oblongata of Rats

American Journal of Hypertension ◽

10.1093/ajh/3.10.800 ◽

1990 ◽

Vol 3 (10_Pt_1) ◽

pp. 800-802 ◽

Cited By ~ 6

Author(s):

Kazushi Tsuda ◽

Menek Goldstein ◽

Yoshiaki Masuyama

Keyword(s):

Neuropeptide Y ◽

Medulla Oblongata ◽

Norepinephrine Release ◽

Inhibitory Effects

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Inhibitory effects of silodosin on the bladder mechanosensitive afferent activities and their relation with bladder myogenic contractions in male rats with bladder outlet obstruction

Neurourology and Urodynamics ◽

10.1002/nau.23547 ◽

2018 ◽

Vol 37 (6) ◽

pp. 1897-1903 ◽

Cited By ~ 3

Author(s):

Naoki Aizawa ◽

Daiji Watanabe ◽

Hiroshi Fukuhara ◽

Tetsuya Fujimura ◽

Haruki Kume ◽

...

Keyword(s):

Bladder Outlet Obstruction ◽

Outlet Obstruction ◽

Male Rats ◽

Inhibitory Effects

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Effect of intranasal administration of neuropeptide Y and single prolonged stress on food consumption and body weight in male rats

Neuropeptides ◽

10.1016/j.npep.2020.102060 ◽

2020 ◽

Vol 82 ◽

pp. 102060

Author(s):

Lidia I. Serova ◽

Evelyn Hansson ◽

Esther L. Sabban

Keyword(s):

Body Weight ◽

Neuropeptide Y ◽

Food Consumption ◽

Intranasal Administration ◽

Male Rats ◽

Single Prolonged Stress ◽

Prolonged Stress

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Suppression of Basal Spontaneous Gonadotropin-Releasing Hormone Neuronal Activity during Lactation: Role of Inhibitory Effects of Neuropeptide Y

Endocrinology ◽

10.1210/en.2008-0962 ◽

2008 ◽

Vol 150 (1) ◽

pp. 333-340 ◽

Cited By ~ 31

Author(s):

Jing Xu ◽

Melissa A. Kirigiti ◽

Michael A. Cowley ◽

Kevin L. Grove ◽

M. Susan Smith

Keyword(s):

Neuropeptide Y ◽

Neuronal Activity ◽

Fluorescent Protein ◽

Resting Membrane Potential ◽

Inhibitory Effects ◽

Gnrh Neurons ◽

Cell Current ◽

Green Fluorescent ◽

Hypothalamic Slices

Increased neuropeptide Y (NPY) activity drives the chronic hyperphagia of lactation and may contribute to the suppression of GnRH activity. The majority of GnRH neurons are contacted by NPY fibers, and GnRH cells express NPY Y5 receptor (Y5R). Therefore, NPY provides a neurocircuitry for information about food intake/energy balance to be directly transmitted to GnRH neurons. To investigate the effects of lactation on GnRH neuronal activity, hypothalamic slices were prepared from green fluorescent protein-GnRH transgenic rats. Extracellular loose-patch recordings determined basal GnRH neuronal activity from slices of ovariectomized control and lactating rats. Compared with controls, hypothalamic slices from lactating rats had double the number of quiescent GnRH neurons (14.51 ± 2.86 vs. 7.04 ± 2.84%) and significantly lower firing rates of active GnRH neurons (0.25 ± 0.02 vs. 0.37 ± 0.03 Hz). To study the NPY-postsynaptic Y5R system, whole-cell current-clamp recordings were performed in hypothalamic slices from control rats to examine NPY/Y5R antagonist effects on GnRH neuronal resting membrane potential. Under tetrodotoxin treatment, NPY hyperpolarized GnRH neurons from −56.7 ± 1.94 to −62.1 ± 1.83 mV; NPY’s effects were blocked by Y5R antagonist. To determine whether increased endogenous NPY tone contributes to GnRH neuronal suppression during lactation, hypothalamic slices were treated with Y5R antagonist. A significantly greater percentage of GnRH cells were activated in slices from lactating rats (52%) compared with controls (28%). These results suggest that: 1) basal GnRH neuronal activity is suppressed during lactation; 2) NPY can hyperpolarize GnRH neurons via postsynaptic Y5R; and 3) increased inhibitory NPY tone during lactation is a component of the mechanisms responsible for suppression of GnRH neuronal activity. Neuropeptide Y (NPY) directly hyperpolarizes GnRH neurons via postsynaptic NPY Y5 receptor. Increased inhibitory NPY tone during lactation is an important component of the suppression of GnRH neuronal activity.

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QUANTITATIVE STUDIES OF HAIR GROWTH IN THE ALBINO RAT

Journal of Endocrinology ◽

10.1677/joe.0.0160351 ◽

1958 ◽

Vol 16 (4) ◽

pp. 351-359 ◽

Cited By ~ 55

Author(s):

ELIZABETH JOHNSON

Keyword(s):

Hair Growth ◽

Female Rats ◽

Male Rats ◽

Hair Length ◽

Inhibitory Effects ◽

Albino Rat ◽

Rate Of Growth ◽

Quantitative Studies ◽

Reduced Rate ◽

Second Wave

SUMMARY 1. Spaying of female rats aged 7 weeks accelerated the passage of the second wave of hair growth. Longer hairs were produced as a result of faster growth, and the rate of loss of dead or 'club' hairs [cf. Johnson, 1958] was increased. 2. Oestradiol implanted into spayed females delayed the initiation and passage of the wave. Shorter hairs were produced by a reduced rate of growth, and loss of club hairs was inhibited. 3. Castration of male rats aged 7 weeks accelerated the passage of the second wave of growth, and implantation of testosterone slowed it down. Testosterone had no effect on the definitive length of hair produced or on the rate at which club hairs were lost. 4. Oestradiol implanted into castrated males produced the same effects as in spayed females except that it had no effect on the time of initiation of the wave. 5. Combined implantation of testosterone with oestradiol into castrated males did not off-set the inhibitory effects of the oestradiol on hair length or rate of loss of club hairs, but may have slightly speeded the hair wave.

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