scholarly journals Sex-dimorphic neuroestradiol regulation of ventromedial hypothalamic nucleus glucoregulatory transmitter and glycogen metabolism enzyme protein expression in the rat

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Md. Main Uddin ◽  
Mostafa M. H. Ibrahim ◽  
Karen P. Briski
Keyword(s):  
Protein Expression ◽  
Glycogen Synthase ◽  
Metabolic Stress ◽  
Glycogen Metabolism ◽  
Female Rats ◽  
Hypothalamic Nucleus ◽  
Energy Yield ◽  
Intact Male ◽  
Energy Deficiency ◽  
Ventromedial Hypothalamic Nucleus

Abstract Background Ventromedial hypothalamic nucleus (VMN) gluco-regulatory transmission is subject to sex-specific control by estradiol. The VMN is characterized by high levels of aromatase expression. Methods The aromatase inhibitor letrozole (LZ) was used with high-resolution microdissection/Western blot techniques to address the hypothesis that neuroestradiol exerts sex-dimorphic control of VMN neuronal nitric oxide synthase (nNOS) and glutamate decarboxylase65/67 (GAD) protein expression. Glycogen metabolism impacts VMN nNOS and GAD profiles; here, LZ treatment effects on VMN glycogen synthase (GS) and phosphorylase brain- (GPbb; glucoprivic-sensitive) and muscle (GPmm; norepinephrine-sensitive) variant proteins were examined. Results VMN aromatase protein content was similar between sexes. Intracerebroventricular LZ infusion of testes-intact male and ovariectomized, estradiol-replaced female rats blocked insulin-induced hypoglycemic (IIH) up-regulation of this profile. LZ exerted sex-contingent effects on basal VMN nNOS and GAD expression, but blocked IIH-induced NO stimulation and GAD suppression in each sex. Sex-contingent LZ effects on basal and hypoglycemic patterns of GPbb and GPmm expression occurred at distinctive levels of the VMN. LZ correspondingly down- or up-regulated baseline pyruvate recycling pathway marker protein expression in males (glutaminase) and females (malic enzyme-1), and altered INS effects on those proteins. Conclusions Results infer that neuroestradiol is required in each sex for optimal VMN metabolic transmitter signaling of hypoglycemic energy deficiency. Sex differences in VMN GP variant protein levels and sensitivity to aromatase may correlate with sex-dimorphic glycogen mobilization during this metabolic stress. Neuroestradiol may also exert sex-specific effects on glucogenic amino acid energy yield by actions on distinctive enzyme targets in each sex.

scholarly journals Norepinephrine Regulation of Ventromedial Hypothalamic Nucleus Astrocyte Glycogen Metabolism

2021 ◽  
Vol 22 (2) ◽  
pp. 759
Author(s):  
Karen P. Briski ◽  
Mostafa M. H. Ibrahim ◽  
A. S. M. Hasan Mahmood ◽  
Ayed A. Alshamrani
Keyword(s):  
Alternative Energy ◽  
Glycogen Synthase ◽  
Glycogen Metabolism ◽  
Receptor Expression ◽  
Hypothalamic Nucleus ◽  
Control Structures ◽  
Ventromedial Hypothalamic Nucleus ◽  
Glycogen Reserve ◽  
Noradrenergic Modulation ◽  
The Brain

The catecholamine norepinephrine (NE) links hindbrain metabolic-sensory neurons with key glucostatic control structures in the brain, including the ventromedial hypothalamic nucleus (VMN). In the brain, the glycogen reserve is maintained within the astrocyte cell compartment as an alternative energy source to blood-derived glucose. VMN astrocytes are direct targets for metabolic stimulus-driven noradrenergic signaling due to their adrenergic receptor expression (AR). The current review discusses recent affirmative evidence that neuro-metabolic stability in the VMN may be shaped by NE influence on astrocyte glycogen metabolism and glycogen-derived substrate fuel supply. Noradrenergic modulation of estrogen receptor (ER) control of VMN glycogen phosphorylase (GP) isoform expression supports the interaction of catecholamine and estradiol signals in shaping the physiological stimulus-specific control of astrocyte glycogen mobilization. Sex-dimorphic NE control of glycogen synthase and GP brain versus muscle type proteins may be due, in part, to the dissimilar noradrenergic governance of astrocyte AR and ER variant profiles in males versus females. Forthcoming advances in the understanding of the molecular mechanistic framework for catecholamine stimulus integration with other regulatory inputs to VMN astrocytes will undoubtedly reveal useful new molecular targets in each sex for glycogen mediated defense of neuronal metabolic equilibrium during neuro-glucopenia.

Ventromedial Hypothalamic Nucleus Glycogen Regulation of Metabolic-Sensory Neuron AMPK and Neurotransmitter Expression: Role of Lactate

2021 ◽  
Author(s):  
Khaggeswar Bheemanapally ◽  
Mostafa M.H. Ibrahim ◽  
Ayed Alshamrani ◽  
Karen P. Briski
Keyword(s):  
Nitric Oxide ◽  
Glycogen Metabolism ◽  
Female Rats ◽  
Hypothalamic Nucleus ◽  
Gamma Aminobutyric Acid ◽  
Ventromedial Hypothalamic Nucleus ◽  
Gaba Neuron ◽  
Amp Activated Protein Kinase ◽  
Corticosterone Release ◽  
Lactate Infusion

Astrocyte glycogen is dynamically remodeled during metabolic stability and provides oxidizable L-lactate equivalents during neuro-glucopenia. Current research investigated the hypothesis that ventromedial hypothalamic nucleus (VMN) glycogen metabolism controls gluco-stimulatory nitric oxide (NO) and/or gluco-inhibitory gamma-aminobutyric acid (GABA) neuron 5'-AMP-activated protein kinase (AMPK) and transmitter marker, e.g. neuronal nitric oxide synthase (nNOS), glutamate decarboxylase65/67 (GAD) protein expression. Adult ovariectomized estradiol-implanted female rats were injected into the VMN with the glycogen phosphorylase inhibitor 1,4-dideoxy-1,4-imino-D-arabinitol (DAB) before vehicle or L-lactate infusion. Western blot analysis of laser-catapult-microdissected nitrergic and GABAergic neurons showed that DAB caused lactate-reversible up-regulation of nNOS and GAD proteins. DAB suppressed or increased total AMPK content of NO and GABA neurons, respectively, by lactate-independent mechanisms, but lactate prevented drug enhancement of pAMPK expression in nitrergic neurons. Inhibition of VMN glycogen disassembly caused divergent changes in counter-regulatory hormone, e.g. corticosterone (increased) and glucagon (decreased) secretion. Outcomes show that VMN glycogen metabolism controls local gluco-regulatory transmission by means of lactate signal volume. Results implicate glycogen-derived lactate deficiency as a physiological stimulus of corticosterone release. Concurrent normalization of nitrergic neuron nNOS and pAMPK protein and corticosterone secretory response to DAB by lactate infers that the hypothalamic-pituitary-adrenal axis may be activated by VMN NO-mediated signals of cellular energy imbalance.

Inhibitory influence of the nuclei of the posterior hypothalamus on the pro-oestrous surge of LH

1984 ◽  
Vol 105 (4) ◽  
pp. 433-440 ◽  
Author(s):  
C. Beltramino ◽  
S. Taleisnik
Keyword(s):  
Posterior Hypothalamus ◽  
Female Rats ◽  
Hypothalamic Nucleus ◽  
Inhibitory Influence ◽  
Medial Basal Hypothalamus ◽  
Mammillary Bodies ◽  
Ventromedial Hypothalamic Nucleus ◽  
Hypothalamic Nuclei ◽  
Posterior Hypothalamic Nucleus ◽  
Lh Release

Abstract. The effect of transecting caudal afferents to the medial basal hypothalamus on the pro-oestrous surge of LH was studied in cyclic female rats. Rats with transverse cuts placed just in front of the mammillary bodies and caudal to the ventromedial hypothalamic nucleus showed an earlier time of onset of pro-oestrous surge of LH. Conversely, rats with transverse cuts placed 2 mm more caudally or with cuts along the lateral edges of the hypothalamus showed no altered release of LH. Advanced release of LH occurred also in rats in which the ventral premammillary nuclei or the posterior hypothalamic nuclei were bilaterally destroyed but not in those sham operated or with lesions in the dorsal premammillary nuclei. The number of ova ovulated was higher in rats bearing lesions of any of these nuclei but enhanced LH release was seen only in animals with lesions of the posterior hypothalamic nuclei. Electrochemical stimulation (anodic d.c., 100 μA, 15 s) applied at noon of pro-oestrus to the ventral premammillary nucleus, dorsal premammillary nucleus or posterior hypothalamic nucleus prevented ovulation and the preovulatory discharge of LH. It is concluded that inputs from nuclei of the posterior hypothalamus are inhibitory for LH release and could participate in determining the timing and magnitude of the pro-oestrous surge of the hormone.

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