Beta-endorphin, ACTH, and catecholamine responses in chronic autonomic failure

Cell apoptosis in the testis of male rats is elevated by intervention with β-endorphin and the mu opioid receptor

β-endorphin (β-EP) is involved in the regulation of male germ cells; however, little is known about the effect of β-EP on primary germ cells via opioid receptors. In this study, we first revealed significant cell apoptosis in the testis of male rats after β-EP intervention. Subsequently, the expression of the mu opioid receptor (MOR) was detected in both Leydig cells (LCs) and spermatogonia (SGs) by fluorescence colocalization; overlapping signals were also detected in apoptotic cells. In addition, LCs and SGs were separated from the testis of male rats and primary cells were treated with β-EP; this increased the mRNA levels of MOR and was accompanied by acute cell apoptosis. Our findings provide a foundation for the further study of apoptosis in reproductive cells regulated by β-EP and the MOR receptor.

The Clash of Two Epidemics: the Relationship Between Opioids and Glucose Metabolism

PURPOSE OF REVIEW

We are currently in the midst of a global opioid epidemic. Opioids affect many physiological processes, but one side effect that is not often taken into consideration is the opioid-induced alteration in blood glucose levels.

RECENT FINDINGS

This review shows that the vast majority of studies report that opioid stimulation increases blood glucose levels. In addition, plasma levels of the endogenous opioid β-endorphin rise in response to low blood glucose. In contrast, in hyperglycaemic baseline conditions such as in patients with type 2 diabetes mellitus (T2DM), opioid stimulation lowers blood glucose levels. Furthermore, obesity itself alters sensitivity to opioids, changes opioid receptor expression and increases plasma β-endorphin levels. Thus, opioid stimulation can have various side effects on glycaemia that should be taken into consideration upon prescribing opioid-based medication, and more research is needed to unravel the interaction between obesity, glycaemia and opioid use.

The supraoptic and paraventricular nuclei in healthy aging and neurodegeneration

The supraoptic (SON) and paraventricular (PVN) nuclei of the hypothalamus undergo structural and functional changes over the course of healthy aging. These nuclei and their connections are also heterogeneously affected by several different neurodegenerative diseases. This chapter reviews the involvement of the SON and PVN, the hypothalamic-pituitary axes, and the peptide hormones produced in both nuclei in healthy aging and in neurodegeneration, with a focus on Alzheimer's disease (AD), frontotemporal dementia (FTD), amyotrophic lateral sclerosis, progressive supranuclear palsy, Parkinson's disease (PD), dementia with Lewy bodies (DLB), multiple system atrophy, and Huntington's disease. Although age-related changes occur in several regions of the hypothalamus, the SON and PVN are relatively preserved during aging and in many neurodegenerative disorders. With aging, these nuclei do undergo some sexually dimorphic changes including changes in size and levels of vasopressin and corticotropin-releasing hormone, likely due to age-related changes in sex hormones. In contrast, oxytocinergic cells and circulating levels of thyrotropin-releasing hormone remain stable. A relative resistance to many forms of neurodegenerative pathology is also observed, in comparison to other hypothalamic and brain regions. Mirroring the pattern observed in aging, pathologic hallmarks of AD, and some subtypes of FTD are observed in the PVN, though to a milder degree than are observed in other brain regions, while the SON is relatively spared. In contrast, the SON appears more vulnerable to alpha-synuclein pathology of DLB and PD. The consequences of these alterations may help to inform several of the physiologic changes observed in aging and neurodegenerative disease.

A cyclic pain: the pathophysiology and treatment of menstrual migraine

Catamenial migraine is a headache disorder occurring in reproductive-aged women relevant to menstrual cycles. Catamenial migraine is defined as attacks of migraine that occurs regularly in at least 2 of 3 consecutive menstrual cycles and occurs exclusively on day 1 to 2 of menstruation, but may range from 2 days before (defined as -2) to 3 days after (defined as +3 with the first day of menstruation as day +1). There are 2 subtypes: the pure menstrual migraine and menstrually related migraine. In pure menstrual migraine, there are no aura and no migraine occurring during any other time of the menstrual cycle. In contrast, menstrually related migraine also occurs in 2 of 3 consecutive menstrual cycles, mostly on days 1 and 2 of menstruation, but it may occur outside the menstrual cycle. Catamenial migraine significantly interferes with the quality of life and causes functional disability in most sufferers. The fluctuation of estrogen levels is believed to play a role in the pathogenesis of catamenial migraine. In this review, we discuss estrogen and its direct and indirect pathophysiologic roles in menstrual-related migraine headaches and the available treatment for women.

TARGET AUDIENCE

Obstetricians and gynecologists, family physicians.

LEARNING OBJECTIVES

After completing this CME activity, physicians should be better able to discuss the pathophysiology of catamenial migraine, identify the risk factors for catamenial migraine among women, and list the prophylactic and abortive treatments for migraines.

Morphological substrate of autonomic failure and neurohormonal dysfunction in multiple system atrophy: impact on determining phenotype spectrum

Autonomic failure is a prominent clinical feature of patients with multiple system atrophy (MSA). Neurohormonal dysfunction is also a frequent accompaniment in patients with MSA. The determination of the pathological involvement of the autonomic neurons, which are responsible for circadian rhythms and responses to stress, provides new insight into autonomic failure and neurohormonal dysfunction in MSA. The disruptions of circadian rhythms and responses to stress may underlie the impairment of homeostatic integration responsible for cardiovascular and respiratory failures. These notions lead to the hypothesis that a pathological involvement of autonomic neurons is a significant factor of the poor prognosis of MSA. Beyond this perspective, endeavors to find the morphological phenotype that represents a predominant loss of autonomic neurons may elucidate the full spectrum of pathological involvements in MSA.

The validity of a hyperventilation test for an investigation of autonomic failure: assessment in patients with multiple system atrophy and Parkinson's disease

Although heart rate (HR) responses to hyperventilation (HV) have been used as a cardiovascular autonomic function test, autonomic involvement during HV remains uncertain. To clarify the relationship between autonomic activity and cardiovascular changes during HV, we compared cardiovascular responses during HV among subjects with different autonomic function, namely 16 patients with probable multiple system atrophy (MSA), 16 with possible MSA, 28 with Parkinson's disease (PD) and 28 healthy controls. Abnormalities of cardiovascular responses to head-up postural change and the Valsalva maneuver were definitely present in the order of probable MSA, possible MSA and PD, and abnormal HR and blood pressure (BP) responses during HV were observed in probable MSA and possible MSA, but not in PD. Unlike the significant difference in standard cardiovascular autonomic function tests, the HR and BP responses during HV were equivalent between probable and possible MSA. These findings suggest that cardiovascular control during HV may be affected not only by autonomic activity but also by other factors.

Multiple system atrophy: pathophysiology and management

Multiple system atrophy (MSA) is a sporadic neurodegenerative disorder that usually manifests when an individual is in his/her early fifties and progresses relentlessly with a mean survival of 9 years. Clinically, MSA is dominated by autonomic/urogenital failure which may be associated with either parkinsonism (MSA-P subtype) in 80% of cases or with cerebellar ataxia (MSA-C subtype) in 20% of cases. Pathologically, MSA is characterised by a neuronal multisystem degeneration and abnormal glial cytoplasmic inclusions containing alpha-synuclein aggregates. Autonomic and urogenital features of MSA should be identified early on because they can be treated effectively in many instances. In contrast, pharmacological treatment of motor features is often disappointing, except for a minority of patients with MSA-P who derive transient benefit from levodopa treatment. In the future, neurotransplantation may extend or improve the treatment response in MSA-P, but further preclinical evidence is required prior to clinical application. Neuroprotection strategies may slow down disease progression in MSA and the results of the first double-blind trial of riluzole (an inhibitor of glutamate release) in patients with MSA will be available in 2004.

Nocturnal body core temperature falls in Parkinson's disease but not in Multiple-System Atrophy

OBJECTIVE

To evaluate whether the circadian rhythm of body core temperature (CRT degrees ) can differentiate Multiple-System Atrophy (MSA) from Idiopathic Parkinson's disease (IPD).

METHODS

We evaluated 14 patients with probable MSA, seven with IPD, and eight controls. After a preliminary evaluation of cardiovascular autonomic function, rectal temperature and sleep-wake cycle were monitored continuously for 48 hours in a temperature-controlled room, at constant bed rest with controlled food intake and fixed light-dark schedule.

RESULTS

MSA patients showed cardiovascular autonomic sympathetic and parasympathetic failure. IPD had normal cardiovascular autonomic function. A 24-hour rhythm of body core temperature (BcT degrees ) was present in all subjects. IPD had CRT degrees comparable to controls. In MSA the mesor was higher and mean BcT degrees of each hour was significantly higher from 11 p.m. to 7 a.m. The analysis of mean BcT degrees during the different sleep phases showed significantly higher values during both NREM (1--2, 3--4) and REM sleep stages in MSA.

CONCLUSIONS

The physiological nocturnal fall of BcT degrees is blunted in MSA patients mainly because BcT degrees did not decrease during sleep. This CRT degrees pattern is not justified by differences in sleep structure and may reflect an impairment of central sympathetic nervous system function.

Stimulation of sympathetic activity by carbon dioxide in patients with autonomic failure compared to normal subjects

In vivo studies selectively assessing preganglionic and central autonomic nervous system activity in patients with autonomic failure have so far been limited to testing pituitary function. In animal experiments carbon dioxide (CO2) selectively stimulates central sympathetic nuclei in the ventrolateral medulla and preganglionic sympathetic neurons in the cervical trunk. This central stimulation seems to overrule less pronounced peripheral vasodilatatory effects. This study addressed the question of whether hypercapnea is a suitable challenge procedure to test preganglionic and central autonomic activity in healthy subjects and in patients with autonomic failure of preganglionic and central origin. Seven patients with multiple system atrophy (MSA) and 30 age-matched healthy volunteers underwent a protocol including a Valsalva manoeuvre (VM) under normo- and hypercapnic conditions and exposure to hypercapnea under supine resting conditions. Blood pressure (BP), heart rate (HR) and end-tidal CO2 partial pressure were measured continuously and non-invasively. In normal controls hypercapnea induced significantly higher BP values in phases II, IIe, III and IV of the VM compared to the normocapnic VM and a significant increase in BP during steady-state supine exposure compared to normocapnic baseline. HR increased significantly only after 40 s of steady-state hypercapnea during the latter challenge. In patients with MSA and autonomic failure, in whom a predominantly preganglionic lesion of the autonomic nervous system is established, no significant effects of hypercapnea on the cardiovascular parameters were found. Although this non-invasive challenge procedure cannot differentiate between pre- and postganglionic autonomic failure, exposure to hypercapnea enables the investigation of efferent autonomic activity to vasoconstrictors generated from autonomic centres in the brainstem and cervical trunk.

The insulin tolerance test and ovine corticotrophin-releasing-hormone test in episodic cluster headache. II: Comparison with low back pain patients

Hypothalamic involvement has been invoked to explain the periodicity of the cluster periods and rhythmicity of the pain attacks in cluster headache. To explore this hypothesis the ovine corticotrophin-releasing headaches sufferers during both cluster period and remission. A group of low back pain patients and healthy subjects comprised the control populations. For the o-CRH test, 7 healthy subjects, 7 low back pain patients, 6 cluster headache patients in remission, and 12 in cluster period were studied. Five healthy subjects, 7 low back pain patients, 6 cluster headache patients in remission, and 9 cluster period were administered the insulin tolerance test. Significantly increased basal cortisol levels were found in cluster headache patients in both illness phases (p < 0.0001), but not in low back pain patients. Significantly reduced cortisol response to the o-CRH test was observed in cluster headache patients in both phases compared to healthy controls (p < 0.02). A blunted ACTH and cortisol response (p < 0.0001 and p < 0.003 respectively) to the insulin tolerance test was present in cluster headache patients in both phases of the illness compared to healthy subjects and low back pain patients. On the contrary, the ACTH surge after insulin induced hypoglycemia was significantly increased in the low back pain patient group (p = 0.02). These results suggest that the altered hypothalamic-pituitary-adrenal axis responsiveness in cluster headache patients is not a consequence of the pain, and point to a central, probably hypothalamic derangement in this pathology.

The head and neck discomfort of autonomic failure: an unrecognized aetiology of headache

Information concerning the frequency, severity, character, location, duration, diurnal pattern of headache and ancillary symptoms were obtained in 25 patients with autonomic failure and 44 control subjects. Precipitating and ameliorating factors were identified. Autonomic failure patients had more head and neck discomfort than controls. Their discomfort was much more likely to localize in the occiput, nape of the neck and shoulder, compared with controls. There was a greater tendency for the discomfort to occur in the morning and after meals. It was sometimes less than 5 min in duration and was often associated with dimming, blurring, or tunnelling of vision. It was provoked by upright posture and relieved by lying down. Patients with severe autonomic failure and orthostatic hypotension often present with a posture-dependent headache or neck pain. Because the relationship of these symptoms to posture is often not recognized, the fact that these findings may signal an underlying autonomic disorder is underappreciated, and the opportunity to consider this aetiology for the headache may be missed.

Cholinergic dysfunction in Shy-Drager syndrome: effect of the parasympathomimetic agent, bethanechol

To determine the frequency, severity and organ distribution of cholinergic dysfunction in the Shy-Drager syndrome, eleven patients were prospectively studied. In addition to documenting adrenergic insufficiency, a battery of twelve tests was employed to assess cholinergic function. Six tests demonstrated pupillary, lacrimal, salivary, urinary bladder, sexual and sudomotor dysfunction in the majority of patients. Cardiac vagal function as studied by the heart rate response to deep breathing, the Valsalva manoeuvre, cold face test, apnoeic facial immersion and atropine test was affected in all patients. Oesophageal motility was abnormal in six patients. Cholinergic dysfunction in patients with the Shy-Drager syndrome was widespread but of variable severity and distribution. Subcutaneous administration of the parasympathomimetic agent bethanechol demonstrated hyperresponsiveness of lacrimal, salivary, oesophageal, bowel, bladder and sudomotor functions. It is suggested that the Shy-Drager syndrome is primarily a preganglionic cholinergic disorder with transsynaptic degeneration accounting for the development of postganglionic cholinergic as well as adrenergic dysfunction.

A review of hormonal findings in cluster headache. Evidence for hypothalamic involvement

The cause of cluster headache remains to be determined. The involvement of peripheral neurovascular structures can explain the pain and autonomic signs of a cluster attack, but not its rhythmicity. The central theory of cluster headache attributes the cyclic recurrence to involvement of the hypothalamus. To evaluate hypothalamic dysfunction a number of hormone studies have been carried out on cluster headache patients. Alterations in plasma melatonin, cortisol, testosterone, gonadotrophins, prolactin, growth hormone and thyrotropin have been documented, some only in the cluster period but others in the remission phase of the illness. We believe that the hormonal abnormalities in cluster headache support disorders of hypothalamic function.

Sex hormones and headache

A variety of evidence suggests a link between migraine and the female sex hormones. Women with migraine outnumber men by at least a 2:1 ratio and definite patterns of development and attacks are noted at menarche and throughout the period of menses, related to trimester of pregnancy, and again at menopause, although it may also regress. Hormonal replacement with estrogen can exacerbate migraine; oral contraceptives can change the character and frequency of migraine headache. This article will cover approaches to the therapy of hormone-related headaches associated with the menstrual cycle, menopause, and oral contraceptives.

The insulin tolerance test and the ovine corticotrophin-releasing hormone test in episodic cluster headache

Clinical observations indicate a central nervous system, probably hypothalamic, involvement in cluster headache pathogenesis. In order to investigate the supposed hypothalamic involvement in cluster headache, we followed the hypothalamic-pituitary-adrenal axis and autonomic responses to the insulin tolerance test and the ovine corticotrophin-releasing hormone test in episodic cluster headache patients, both during remission and during the cluster period. The study revealed increased basal cortisol levels in all cluster patients. A blunted cortisol response to ovine corticotrophin-releasing hormone, in spite of a normal ACTH surge, was subsequently found in both illness phases. These findings suggest hypothalamic-pituitary-adrenal axis hyperactivity in both cluster phases. Furthermore, reduced ACTH and cortisol responses after insulin challenge were also observed in both remission and cluster period patients; a reduced norepinephrine surge was seen only in the cluster period. Taken together, these results suggest a hypothalamic involvement in the altered neuroendocrinological and autonomic responses found in our patients.

Central and peripheral effects of arecoline in patients with autonomic failure

Increased plasma adrenalin (A) levels following arecoline in normal subjects and patients with multiple system atrophy (MSA) may result from nicotinic adrenal stimulation. Lack of this response in patients with pure autonomic failure (PAF) is consistent with peripheral sympathetic dysfunction. The mechanisms underlying diminished plasma corticotropin (ACTH) responses to arecoline may differ in patients with autonomic failure. Hypothalamic, cholinergic degeneration could prevent the response in MSA whereas patients with PAF do not manifest the normal increase in A which may be required to elicit an ACTH response. The appearance and exacerbation of tremor, vertigo, and pathological affect in the MSA group suggest that some central cholinergic receptors remain functional.

Release of vasopressin, cortisol and beta-endorphin in tetraplegic subjects in response to head-up tilt

Plasma levels of beta-endorphin, vasopressin and cortisol during head-up tilt were measured in tetraplegic patients and in normal healthy subjects. In tetraplegic patients rapid tilt from the horizontal to 30 degrees or 60 degrees head-up induced orthostatic hypotension and increased plasma levels of cortisol, beta-endorphin and vasopressin. In control subjects head-up tilt failed to alter plasma levels of these hormones. These data show that the head-up position in tetraplegics causes various endocrine reactions.