Effects of female sex hormones on responses to CGRP, acetylcholine, and 5-HT in rat isolated arteries

O-GlcNAc impairs endothelial function in uterine arteries from virgin but not pregnant rats: The role of GSK3β

Increased O-Linked β-N-acetylglucosamine (O-GlcNAc) is observed in several pathologies, and unbalanced O-GlcNAcylation levels favor endothelial dysfunction. Whether augmented O-GlcNAc impacts the uterine artery (UA) function and how it affects the UA during pregnancy remains to be elucidated. We hypothesized that glucosamine treatment increases O-GlcNAc, leading to uterine artery dysfunction and this effect is prevented by pregnancy. Pregnant (P) and non-pregnant (NP) Wistar rats were treated with glucosamine (300 mg/kg; i.p.) for 21 days. Concentration response-curves (CRC) to acetylcholine (in the presence or absence of L-NAME) and sodium nitroprusside were performed in UAs. In NP rats, glucosamine treatment increased O-GlcNAc expression in UAs accompanied by decreased endothelium-dependent relaxation, which was abolished by L-NAME. Endothelial nitric oxide synthase (eNOS) activity and total Akt expression were decreased by glucosamine-treatment in NP rats. Further, NP rats treated with glucosamine displayed increased glycogen synthase kinase 3 beta (GSK3β) activation and O-GlcNAc-transferase (OGT) expression in the UA. P rats treated with glucosamine displayed decreased O-GlcNAc in UAs and it was accompanied by improved relaxation to acetylcholine, whereas eNOS and GSK3β activity and total Akt and OGT expression were unchanged. Sodium nitroprusside-induced relaxation was not changed in all groups, indicating that glucosamine treatment led to endothelial dysfunction in NP rats. The underlying mechanism is, at least in part, dependent on Akt/GSK3β/OGT modulation. We speculate that during pregnancy, hormonal alterations play a protective role in preventing O-GlcNAcylation-induced endothelial dysfunction in the UAs.

Menstrual migraine: what it is and does it matter?

The diagnostic criteria of menstrual migraine (MM), migraine related to menstruation and pure menstrual migraine, are placed in the appendix of the International Classification of Headache Disorders and are still primarily considered as research criteria that need validation. Although there is a great wealth of knowledge about the neurobiological processes underlying MM and its symptoms, the mechanisms by which an attack starts during the menstrual cycle remain baffling, and the disease is still undertreated. In this narrative review, we aim to summarize recent data on pathophysiology, epidemiology, burden of disease and treatment of MM. The vast majority of the literature focuses on the relationship between MM and hormonal factors. The role of falling in estrogen levels is believed to increase the susceptibility of blood vessels to prostaglandins, which have been implicated in neurogenic inflammation. Moreover, fluctuations of ovarian steroid hormone levels modulate calcitonin gene-related peptide in the trigeminovascular system. In addition, it has been observed that gonadal hormones modulate cortical spreading depression susceptibility in animal models. Sex hormone influences on MM affect not only the frequency and severity of headache attack but also its treatment. Understanding the mechanisms that contribute to neuroendocrine vulnerability in some women and some menstrual cycles may yield possible marker of the disease opening treatment options specifically targeting MM. An increased interest for future research on the subject will further elucidate how to manage this debilitating type of migraine.

Gender aspects of CGRP in migraine

Background

Migraine is two to three times more prevalent in women than in men, but the mechanisms involved in this gender disparity are still poorly understood. In this respect, calcitonin gene-related peptide (CGRP) plays a key role in migraine pathophysiology and, more recently, the functional interactions between ovarian steroid hormones, CGRP and the trigeminovascular system have been recognized and studied in more detail.

Aims

To provide an overview of CGRP studies that have addressed gender differences utilizing animal and human migraine preclinical research models to highlight how the female trigeminovascular system responds differently in the presence of varying ovarian steroid hormones.

Conclusions

Gender differences are evident in migraine. Several studies indicate that fluctuations of ovarian steroid hormone (mainly estrogen) levels modulate CGRP in the trigeminovascular system during different reproductive milestones. Such interactions need to be considered when conducting future animal and human experiments, since these differences may contribute to the development of gender-specific therapies.

Heteroreceptors Modulating CGRP Release at Neurovascular Junction: Potential Therapeutic Implications on Some Vascular-Related Diseases

Calcitonin gene-related peptide (CGRP) is a 37-amino-acid neuropeptide belonging to the calcitonin gene peptide superfamily. CGRP is a potent vasodilator with potential therapeutic usefulness for treating vascular-related disease. This peptide is primarily located on C- and Aδ-fibers, which have extensive perivascular presence and a dual sensory-efferent function. Although CGRP has two major isoforms (α-CGRP and β-CGRP), the α-CGRP is the isoform related to vascular actions. Release of CGRP from afferent perivascular nerve terminals has been shown to result in vasodilatation, an effect mediated by at least one receptor (the CGRP receptor). This receptor is an atypical G-protein coupled receptor (GPCR) composed of three functional proteins: (i) the calcitonin receptor-like receptor (CRLR; a seven-transmembrane protein), (ii) the activity-modifying protein type 1 (RAMP1), and (iii) a receptor component protein (RCP). Although under physiological conditions, CGRP seems not to play an important role in vascular tone regulation, this peptide has been strongly related as a key player in migraine and other vascular-related disorders (e.g., hypertension and preeclampsia). The present review aims at providing an overview on the role of sensory fibers and CGRP release on the modulation of vascular tone.

Calcitonin gene-related peptide: physiology and pathophysiology

Calcitonin gene-related peptide (CGRP) is a 37-amino acid neuropeptide. Discovered 30 years ago, it is produced as a consequence of alternative RNA processing of the calcitonin gene. CGRP has two major forms (α and β). It belongs to a group of peptides that all act on an unusual receptor family. These receptors consist of calcitonin receptor-like receptor (CLR) linked to an essential receptor activity modifying protein (RAMP) that is necessary for full functionality. CGRP is a highly potent vasodilator and, partly as a consequence, possesses protective mechanisms that are important for physiological and pathological conditions involving the cardiovascular system and wound healing. CGRP is primarily released from sensory nerves and thus is implicated in pain pathways. The proven ability of CGRP antagonists to alleviate migraine has been of most interest in terms of drug development, and knowledge to date concerning this potential therapeutic area is discussed. Other areas covered, where there is less information known on CGRP, include arthritis, skin conditions, diabetes, and obesity. It is concluded that CGRP is an important peptide in mammalian biology, but it is too early at present to know if new medicines for disease treatment will emerge from our knowledge concerning this molecule.

Expression of the small conductance Ca²⁺-activated potassium channel subtype 3 (SK3) in rat uterus after stimulation with 17β-estradiol

Preterm births accounts for roughly 9% of all births worldwide and can have detrimental or even lethal consequences for the infant. However to develop new treatment that will lower the rate of preterm births, more knowledge is required on the factors contributing to the contraction and relaxation of the myometrium. The small conductance Ca²⁺-activated potassium channel subtype 3 (SK3) has been identified in the myometrium of several species including humans, mice and rats, but with great inter species variation of the expression pattern and regulation. The aim of this study was to investigate the expression of SK3 in the uterus of rats stimulated with 17β-estradiol and progesterone in order to get an in depth understanding of the rat uterine SK3. Using immunohistochemistry SK3 was localized to the glandular and luminal endometrial lamina epitheliali. Furthermore, a weak signal was observed in the myometrium. Using Western blot the protein level of SK3 was found to increase in uteri from animals treated with 17β-estradiol, an effect that was not reflected at the mRNA level. The levels of mRNA for SK3 were significantly lower in the uterus of 17β-estradiol-treated animals than in the uterus of ovariectomized animals. We conclude that the SK channels are present in the endometrial epithelium, and possibly also in the myometrium of the rat uterus. Furthermore, the hormonal effect on SK3 caused by 17β-estradiol includes divergent regulation at mRNA and protein levels.

Scopolamine produces larger antidepressant and antianxiety effects in women than in men

Some antidepressant agents generate differential benefit based on gender. Blocking cholinergic muscarinic receptors using scopolamine produces robust and rapid antidepressant effects in males and females combined. This study evaluated if males and females differ in the antidepressant response magnitude following scopolamine administration. A total of 52 male and female outpatients meeting criteria for recurrent major depressive or bipolar disorder participated in a double-blind, randomized, placebo-controlled, crossover clinical trial involving seven i.v. infusions of placebo or scopolamine (4 μg/kg). Following a single-blind placebo lead-in, participants entered either a placebo-block/scopolamine-block or a scopolamine-block/placebo-block sequence. Each block included three sessions. Clinical ratings were acquired before each infusion and included the Montgomery-Asberg Depression Rating Scale (MADRS) and the Hamilton Anxiety Rating Scale (HAM-A). A treatment group × block interaction (F=21.0, p<0.001) was observed in MADRS scores across gender, and the reduction was significant by the evaluation following the first scopolamine administration (F=8.4, p=0.006). The treatment group × block interaction was also significant in males (F=3.8, p=0.043) and females (F=35.6, p<0.001) separately. A block × gender interaction (F=7.4, p=0.009) indicated that the response magnitude was larger in women. The treatment × block interaction was significant for the HAM-A across gender (F=12.0, p<0.001), and was significant for females (F=24.9, p<0.001) but not for males (F=1.3, p=0.30). When comparing the baseline block to study end, the block × gender interaction (F=12.6, p=0.001) showed that the antianxiety response was greater in women. Men and women show a rapid antidepressant response following scopolamine, but the magnitude of response is larger in women than in men.

Age-related changes in dorsal root ganglia, circulating and vascular calcitonin gene-related peptide (CGRP) concentrations in female rats: effect of female sex steroid hormones

The aim of the present study is to investigate whether immunoreactive (I) calcitonin gene-related peptide (CGRP) content is decreased in plasma and mesenteric arteries (resistance arteries) in middle-aged rats and if so, whether sex steroid hormones enhance I-CGRP in middle-aged female rats. We also examined whether vascular CGRP receptor components, calcitonin receptor like receptor (CRLR) and receptor activity modifying protein 1 (RAMP1) are elevated by sex steroid hormones treatment in middle-aged female rats. Young adult (3 months old) and middle-aged (10-12 months old) ovariectomized rats were treated subcutaneously with estradiol-17beta (E2; 2 mg), progesterone (P4; 5 mg), E2+P4 (2 mg+20 mg) or placebo (control). Radioimmunoassay and Western blot analysis were performed to measure I-CGRP content and CGRP receptor components in dorsal root ganglia (DRG), in resistance arteries and in plasma. Immunofluorescent staining methods were employed to determine cellular localization of CRLR, RAMP1 in resistance arteries. Our data demonstrated that I-CGRP content was significantly (p<0.05) lower in the plasma and resistance arteries of middle-aged female rats compared to young controls. Both RAMP1 and CRLR were concentrated in vascular endothelium and the underlying smooth muscle cells. RAMP1 but not CRLR appeared to be decreased in middle-aged rat vasculature. Chronic perfusion of sex steroid hormones to ovariectomized rats: 1 significantly (p<0.05) elevated I-CGRP in the DRG and in the plasma, and (2) significantly elevated RAMP1 (p<0.05) but did not alter CRLR in resistance arteries. These data suggest that female sex steroid treatment enhances I-CGRP and its receptors, and thus regulate the blood pressure in aged female rats.