Old and new tools to study human brain physiology: Current state, future directions and implications for metabolic regulation

The chronic effect of cortisol on orchestrating cerebral blood flow and brain functional connectivity: evidence from Cushing's disease

BACKGROUND

Cortisol has long been considered to play a crucial role in the pathogenesis of stress-related disorders. Cushing's disease (CD) provides an excellent "hyperexpression model" to investigate the chronic effects of cortisol on brain physiology and cognition. Previous studies have shown that cortisol is associated with neurophysiological alterations in animal models, which has also been examined by neural activity and cerebral blood flow (CBF) in human studies. However, the manner in which cortisol affects the coupling between brain activity and metabolic demand remains largely unknown.

METHODS

Here we used functional magnetic resonance imaging and arterial-spin-labeling imaging to investigate neurophysiological coupling by examining the ratio of CBF and functional connectivity strength (FCS) in 100 participants (47 CD patients and 53 healthy controls).

RESULTS

The results showed that CD was associated with lower CBF-FCS coupling predominantly in regions involving cognitive processing, such as the left dorsolateral prefrontal cortex and precuneus, as well as greater CBF-FCS coupling in subcortical structures, including the bilateral thalamus, right putamen, and hippocampus (P < 0.05, false discovery rate corrected). Moreover, regions with disrupted CBF-FCS coupling were associated with cortisol dosage and cognitive decline in CD patients.

CONCLUSIONS

Together, these findings elucidate the effect of cortisol excess on cerebral microenvironment regulation and associated cognitive disturbances in the human brain.

Reversibility of cerebral blood flow in patients with Cushing's disease after surgery treatment

BACKGROUND AND OBJECTIVES

Cushing's disease (CD) patients have metabolic abnormalities in the brain caused by excessive exposure to endogenous cortisol. However, the reversibility of brain metabolism of CD patients after treatment remains largely unknown.

METHODS

This study recruited 50 CD patients seeking treatment and 34 matched normal controls (NCs). The patients were treated with Transsphenoidal Adenomectomy (TSA) and reexamined 3 months later. Cerebral blood flow (CBF) of the patients was assessed using 3D pseudo-continuous arterial spin labelling (PCASL) imaging before the treatment and at the 3-month follow-up and were compared with CBF measure of the NCs using a whole-brain voxelwise group comparison method. For remitted patients, their CBF measures and hormone level measures, including adrenocorticotropic hormone (ACTH), 24-hour urinary free cortisol (24hUFC) and serum cortisol, were compared before and after the treatment. Finally, a correlation analysis was carried out to explore the relationship between changes of CBF and hormone level measures of the remitted CD patients.

RESULTS

After the treatment, 45 patients reached remission. Compared with the NCs, the CD patients before the treatment exhibited significantly reduced CBF in cortical regions, including occipital lobe, parietal lobe, superior/middle/inferior temporal gyrus, superior/middle/inferior frontal gyrus, orbitofrontal cortex, precentral gyrus, middle/posterior cingulate gyrus, and rolandic operculum, as well as significantly increased CBF in subcortical structures, including caudate, pallidum, putamen, limbic lobe, parahippocampal gyrus, hippocampus, thalamus, and amygdala (p < 0.01, false discovery rate corrected). For the remitted patients, the change in CBF before and after the treatment displayed a spatial pattern similar to the difference between the NCs and the CD patients before the treatment, and no significant difference in CBF was observed between the NCs and the remitted CD patients after the treatment. The changes of 24hUFC were significantly correlated with the changes of averaged CBF within the subcortical region in the remitted patients (p = 0.01).

CONCLUSIONS

Our findings demonstrate that the brain metabolic abnormalities of CD patients are reversible when their hormone level changes towards normal after surgery treatment.

GnRH Deficient Patients With Congenital Hypogonadotropic Hypogonadism: Novel Genetic Findings in ANOS1, RNF216, WDR11, FGFR1, CHD7, and POLR3A Genes in a Case Series and Review of the Literature

Background: Congenital hypogonadotropic hypogonadism (CHH) is a rare genetic disease caused by Gonadotropin-Releasing Hormone (GnRH) deficiency. So far a limited number of variants in several genes have been associated with the pathogenesis of the disease. In this original research and review manuscript the retrospective analysis of known variants in ANOS1 (KAL1), RNF216, WDR11, FGFR1, CHD7, and POLR3A genes is described, along with novel variants identified in patients with CHH by the present study. Methods: Seven GnRH deficient unrelated Cypriot patients underwent whole exome sequencing (WES) by Next Generation Sequencing (NGS). The identified novel variants were initially examined by in silico computational algorithms and structural analysis of their predicted pathogenicity at the protein level was confirmed. Results: In four non-related GnRH males, a novel X-linked pathogenic variant in ANOS1 gene, two novel autosomal dominant (AD) probably pathogenic variants in WDR11 and FGFR1 genes and one rare AD probably pathogenic variant in CHD7 gene were identified. A rare autosomal recessive (AR) variant in the SRA1 gene was identified in homozygosity in a female patient, whilst two other male patients were also, respectively, found to carry novel or previously reported rare pathogenic variants in more than one genes; FGFR1/POLR3A and SRA1/RNF216. Conclusion: This report embraces the description of novel and previously reported rare pathogenic variants in a series of genes known to be implicated in the biological development of CHH. Notably, patients with CHH can harbor pathogenic rare variants in more than one gene which raises the hypothesis of locus-locus interactions providing evidence for digenic inheritance. The identification of such aberrations by NGS can be very informative for the management and future planning of these patients.