Orofacial skin inflammation increases the number of macrophages in the maxillary subregion of the rat trigeminal ganglion in a corticosteroid-reversible manner

Inflammatory Orofacial Pain Activates Peptidergic Neurons and Upregulates the Oxytocin Receptor Expression in Trigeminal Ganglion

The majority of orofacial pain is caused by musculoskeletal and neuropathological diseases related to inflammatory processes that lead even to transcriptional alterations in the trigeminal ganglion (TG) neurons. The hypothalamic nonapeptide oxytocin has been reported to modulate nociception via binding and activating its receptor in primary sensory neurons. The purpose of this study was to analyze the gene expression of the oxytocin receptor (OTR), c-Fos, an indicator of neuronal activity, and α-calcitonin gene-related peptide (αCGRP), a characteristic neurotransmitter of the peptidergic trigeminal primary afferents in an animal model of inflammation-induced orofacial pain. Carrageenan was unilaterally injected into the vibrissal pads of male and female adult Wistar rats. RT-qPCR was performed to analyze the levels of mRNA expression in TGs 24 h after injection. The gene expression analysis revealed higher fold changes regarding the c-Fos (mean ± S.E: ♀: 3.9 ± 0.19; ♂: 3.55 ± 0.18) and αCGRP (♀: 2.84 ± 0.13; ♂: 3.39 ± 0.47) expression levels of mRNA, and a moderate rise in the expression of the OTR mRNA (♀: 1.52 ± 0.07; ♂: 1.49 ± 0.07) was observed in comparison to both vehicle(saline)-treated and untreated controls. Our results furnish evidence for inflammation-induced activation of peptidergic neurons, and it is suggested that oxytocin modulates inflammation-induced nociception by enhancing their signaling capacity due to its elevated expression in the sensory ganglion cells, thus providing new therapies for orofacial pain relief that target the OTRs.

Immunofluorescent Evidence for Nuclear Localization of Aromatase in Astrocytes in the Rat Central Nervous System

Estrogens regulate a variety of neuroendocrine, reproductive and also non-reproductive brain functions. Estradiol biosynthesis in the central nervous system (CNS) is catalyzed by the enzyme aromatase, which is expressed in several brain regions by neurons, astrocytes and microglia. In this study, we performed a complex fluorescent immunocytochemical analysis which revealed that aromatase is colocalized with the nuclear stain in glial fibrillary acidic protein (GFAP) positive astrocytes in cell cultures. Confocal immunofluorescent Z-stack scanning analysis confirmed the colocalization of aromatase with the nuclear DAPI signal. Nuclear aromatase was also detectable in the S100β positive astrocyte subpopulation. When the nuclear aromatase signal was present, estrogen receptor alpha was also abundant in the nucleus. Immunostaining of frozen brain tissue sections showed that the nuclear colocalization of the enzyme in GFAP-positive astrocytes is also detectable in the adult rat brain. CD11b/c labelled microglial cells express aromatase, but the immunopositive signal was distributed only in the cytoplasm both in the ramified and amoeboid microglial forms. Immunostaining of rat ovarian tissue sections and human granulosa cells revealed that aromatase was present only in the cytoplasm. This novel observation suggests a new unique mechanism in astrocytes that may regulate certain CNS functions via estradiol production.

α6-Containing GABAA Receptors: Functional Roles and Therapeutic Potentials

GABAA receptors containing the α6 subunit are highly expressed in cerebellar granule cells and less abundantly in many other neuronal and peripheral tissues. Here, we for the first time summarize their importance for the functions of the cerebellum and the nervous system. The cerebellum is not only involved in motor control but also in cognitive, emotional, and social behaviors. α6βγ2 GABAA receptors located at cerebellar Golgi cell/granule cell synapses enhance the precision of inputs required for cerebellar timing of motor activity and are thus involved in cognitive processing and adequate responses to our environment. Extrasynaptic α6βδ GABAA receptors regulate the amount of information entering the cerebellum by their tonic inhibition of granule cells, and their optimal functioning enhances input filtering or contrast. The complex roles of the cerebellum in multiple brain functions can be compromised by genetic or neurodevelopmental causes that lead to a hypofunction of cerebellar α6-containing GABAA receptors. Animal models mimicking neuropsychiatric phenotypes suggest that compounds selectively activating or positively modulating cerebellar α6-containing GABAA receptors can alleviate essential tremor and motor disturbances in Angelman and Down syndrome as well as impaired prepulse inhibition in neuropsychiatric disorders and reduce migraine and trigeminal-related pain via α6-containing GABAA receptors in trigeminal ganglia. Genetic studies in humans suggest an association of the human GABAA receptor α6 subunit gene with stress-associated disorders. Animal studies support this conclusion. Neuroimaging and post-mortem studies in humans further support an involvement of α6-containing GABAA receptors in various neuropsychiatric disorders, pointing to a broad therapeutic potential of drugs modulating α6-containing GABAA receptors. SIGNIFICANCE STATEMENT: α6-Containing GABAA receptors are abundantly expressed in cerebellar granule cells, but their pathophysiological roles are widely unknown, and they are thus out of the mainstream of GABAA receptor research. Anatomical and electrophysiological evidence indicates that these receptors have a crucial function in neuronal circuits of the cerebellum and the nervous system, and experimental, genetic, post-mortem, and pharmacological studies indicate that selective modulation of these receptors offers therapeutic prospects for a variety of neuropsychiatric disorders and for stress and its consequences.

Equine Penile Squamous Cell Carcinomas as a Model for Human Disease: A Preliminary Investigation on Tumor Immune Microenvironment

Penile squamous cell carcinomas (SCCs) are common tumors in older horses, with poor prognosis mostly due to local invasion and recurrence. These tumors are thought to be mainly caused by Equus caballus papillomavirus type 2 (EcPV-2). The aim of this study is to characterize the tumor immune environment (TIME) in equine penile tumors. Equine penile epithelial tumors (17 epSCCs; 2 carcinomas in situ, CIS; 1 papilloma, P) were retrospectively selected; immune infiltrate was assessed by histology and immunohistochemistry; RT-qPCR tested the expression of selected chemokines and EcPV-2 DNA and RNA. The results confirmed EcPV-2-L1 DNA in 18/20 (90%) samples. L1 expression was instead retrieved in 13/20 cases (65%). The samples showed an increased infiltration of CD3⁺lymphocytes, macrophages (MAC387; IBA1), plasma cells (MUM1), and FoxP3⁺lymphocytes in the intra/peritumoral stroma when compared to extratumoral tissues (p < 0.05). Only MAC387⁺neutrophils were increased in EcPV-2^high viral load samples (p < 0.05). IL12/p35 was differentially expressed in EcPV^high and EcPV^low groups (p = 0.007). A significant decrease of IFNG and IL2 expression was highlighted in TGFB1-positive samples (p < 0.05). IBA1 and CD20 were intratumorally increased in cases where IL-10 was expressed (p < 0.005). EpSCCs may represent a good spontaneous model for the human counterpart. Further prospective studies are needed in order to confirm these preliminary results.