Factors impacting Catecholamines in Caregivers of Patients with Dementia

Background: Caregivers of dementia patients have significantly higher levels of serum IL-6 and CRP compared to non-caregivers, and the accumulation of everyday stressors reportedly promotes the induction of inflammatory markers. However, few studies have identified factors that affect catecholamine levels in caregivers who experience a combination of physical and mental stress from caregiving.Purpose: This study aimed to identify physical factors that impact catecholamine levels in caregivers of dementia patients.Methods: Participants were elderly caregivers living together with elderly Alzheimer’s-type dementia patients. We performed logistic regression analysis, with levels of adrenaline, noradrenaline, and dopamine (indicators of catecholamine) as dependent variables.Results: Caregiver BMI had a significant impact on adrenaline levels (OR: 0.792; 95%CI: 0.654-0.960) and noradrenaline levels (OR: 1.210; 95%CI: 1.009-1.451), whereas age had a significant impact on dopamine levels (OR: 1.162; 95%CI: 1.019-1.324).Discussion: While caregiver BMI significantly impacted adrenaline and noradrenaline levels, the mechanism underlying these relationships is unclear. One possibility is that obesity (BMI) and a rise in sympathetic nerve activity contributed to hypertension. Our findings suggest that chronic stress in elderly caregivers may potentially impair the dopaminergic activation system in the brain.Conclusion: There is a need to identify factors which increase BMI in caregivers. Future studies aimed at gaining a better understanding of the lifestyle habits of caregivers and intervention studies aimed at reducing their BMI are warranted.

Mercury in the human adrenal medulla could contribute to increased plasma noradrenaline in aging

Plasma noradrenaline levels increase with aging, and this could contribute to the sympathetic overactivity that is associated with essential hypertension and the metabolic syndrome. The underlying cause of this rise in noradrenaline is unknown, but a clue may be that mercury increases noradrenaline output from the adrenal medulla of experimental animals. We therefore determined the proportion of people from 2 to 104 years of age who had mercury in their adrenal medulla. Mercury was detected in paraffin sections of autopsied adrenal glands using two methods of elemental bioimaging, autometallography and laser ablation-inductively coupled plasma-mass spectrometry. Mercury first appeared in cells of the adrenal medulla in the 21–40 years group, where it was present in 52% of samples, and increased progressively in frequency in older age groups, until it was detected in 90% of samples from people aged over 80 years. In conclusion, the proportion of people having mercury in their adrenal medulla increases with aging. Mercury could alter the metabolism of catecholamines in the adrenal medulla that leads to the raised levels of plasma noradrenaline in aging. This retrospective autopsy study was not able to provide a definitive link between adrenal mercury, noradrenaline levels and hypertension, but future functional human and experimental studies could provide further evidence for these associations.

Giant secretory multifocal adrenal myelolipoma: a diagnostic dilemma

A 38-yearr-old man presented with erectile dysfunction and infertility. On examination, he was hypertensive and detected to have a left flank mass. Blood investigations were unremarkable except raised serum noradrenaline levels. Imaging revealed multiple well-defined fat-containing hypodense lesions in left suprarenal area with largest one measuring 14×16 cm, suggestive of left adrenal myelolipoma. Diagnostic dilemma was posed due to discordance between clinical, biochemical and imaging findings. Left adrenal mass resection was planned keeping the possibility of pheochromocytoma. However, histopathology revealed it to be adrenal myelolipoma. Hypertension was resolved in the postoperative period and serum noradrenaline levels were normalised. Final diagnosis of a secretary adrenal myelolipoma was made, which is an extremely rare entity

Differential encoding of signals and preferences by noradrenaline in the anuran brain

ABSTRACTSocial preferences enable animals to selectively interact with some individuals over others. One influential idea for the evolution of social preferences is that preferred signals evolve because they elicit greater neural responses from sensory systems. However, in juvenile plains spadefoot toad (Spea bombifrons), a species with condition-dependent mating preferences, responses of the preoptic area, but not of the auditory midbrain, mirror adult social preferences. To examine whether this separation of signal representation from signal valuation generalizes to other anurans, we compared the relative contributions of noradrenergic signalling in the preoptic area and auditory midbrain of S. bombifrons and its close relative Spea multiplicata. We manipulated body condition in juvenile toads by controlling diet and used high pressure liquid chromatography to compare call-induced levels of noradrenaline and its metabolite MHPG in the auditory midbrain and preoptic area of the two species. We found that calls from the two species induced different levels of noradrenaline and MHPG in the auditory system, with higher levels measured in both species for the more energetic S. bombifrons call. In contrast, noradrenaline levels in the preoptic area mirrored patterns of social preferences in both S. bombifrons and S. multiplicata. That is, noradrenaline levels were higher in response to the preferred calls within each species and were modified by diet in S. bombifrons (with condition-dependent preferences) but not S. multiplicata (with condition-independent preferences). Our results are consistent with a potentially important role for preoptic noradrenaline in the development of social preferences and indicate that it could be a target of selection in the evolution of condition-dependent social preferences.

Pharmacological evidence for the implication of noradrenaline in effort

The trade-off between effort and reward is one of the main determinants of behavior and its alteration is at the heart of major disorders such as depression or Parkinson’s disease. Monoaminergic neuromodulators are thought to play a key role in this trade-off, but their relative contribution remains unclear. Rhesus monkeys (Macaca mulatta) performed a choice-task requiring a trade-off between the volume of fluid reward and the amount of force to be exerted on a grip. In line with a causal role of noradrenaline in effort, decreasing noradrenaline levels with systemic clonidine injections (0.01mg/kg) decreased exerted force and enhanced the weight of upcoming force on choices, without any effect on reward sensitivity. Computational modeling demonstrated that NA acted on a single hidden variable, which affected both choices (as a variable of decision) and force production (as a driving force). Thus, our data strongly support noradrenaline’s implication in effort processing.

Strategies to Treat Chronic Pain and Strengthen Impaired Descending Noradrenergic Inhibitory System

Gabapentinoids (gabapentin and pregabalin) and antidepressants (tricyclic antidepressants and serotonin noradrenaline reuptake inhibitors) are often used to treat chronic pain. The descending noradrenergic inhibitory system from the locus coeruleus (LC) to the dorsal horn of the spinal cord plays an important role in the analgesic mechanisms of these drugs. Gabapentinoids activate the LC by inhibiting the release of γ-aminobutyric acid (GABA) and inducing the release of glutamate, thereby increasing noradrenaline levels in the spinal cord. Antidepressants increase noradrenaline levels in the spinal cord by inhibiting reuptake, and accumulating noradrenaline inhibits chronic pain through α2-adrenergic receptors in the spinal cord. Recent animal studies, however, revealed that the function of the descending noradrenergic inhibitory system is impaired in chronic pain states. Other recent studies found that histone deacetylase inhibitors and antidepressants restore the impaired noradrenergic descending inhibitory system acting on noradrenergic neurons in the LC.

Evaluation of human pineal gland acetylserotonin O-methyltransferase immunoreactivity in suicide: A preliminary study

Disorders of the serotonergic system are especially known to be present in the neurobiology of suicidal behavior. Studies investigating melatonin levels show that changes in pineal gland functions may also play a role in the pathogenesis of suicide. However, to our knowledge, there are no studies evaluating the activity of pinealocytes responsible for melatonin synthesis in suicide. This preliminary study aimed to investigate the relationship among pinealocyte, acetylserotonin O-methyltransferase (ASMT) immunoreactivity, and suicide. Samples of pineal gland, cerebrospinal fluid, blood, and urine were obtained from 21 suicide and 21 non-suicide cases on which medicolegal autopsies were performed. Expression of ASMT in human pineal gland was evaluated by immunohistochemical methods. A scoring system was used to define the anti-ASMT-positive staining in the sections. Enzyme-linked immunosorbent assays were employed to assess serum and cerebrospinal fluid melatonin levels and blood and urine noradrenaline levels. The ASMT-immunopositive pinealocyte count was observed to be lower in suicide cases compared to the non-suicide cases. With the exception of two cases (with moderate staining), all graded scores were 3 (strong staining) in non-suicide group, whereas scores were 1 (mild staining) or 2 (moderate staining) in the suicide group. Melatonin levels in the blood were lower among the suicide victims. These results support decreased pineal gland activity in suicide. However, further studies are needed to assess whether these changes are related to a psychiatric disorder.