Circadian Clock Proteins and Melatonin Receptors in Neurons and Glia of the Sapajus apella Cerebellum

Abstract

Oscillations of brain proteins in circadian rhythms are important for determining several cellular and physiological processes in anticipation of daily and seasonal environmental rhythms. In addition to the suprachiasmatic nucleus, the primary central oscillator, the cerebellum shows oscillations in gene and protein expression. The variety of local circuit rhythms that the cerebellar cortex contains influences functions such as motivational processes, regulation of feeding, food anticipation, language, and working memory. The molecular basis of the cerebellar oscillator has been demonstrated by “clock gene” expression within cells of the cerebellar layers. Genetic and epidemiological evidence suggests that disruption of circadian rhythms in humans can lead to many pathological conditions. Despite this importance, data about clock gene and protein expression in the cerebellum of diurnal (day-active) species, specifically primates, is currently poorly explored, mainly in regard to cellular identity, as well as the relationship with other molecules also involved in cerebellar functions. These studies could contribute to clarification of the possible mechanisms behind cerebellar rhythmicity. Considering that calcium binding proteins (CaBPs) play crucial roles in preserving and modulating cerebellar functions and that clock gene expression can be controlled by afferent projections or paracrine circadian signals such as the hormone melatonin, the present study aimed to describe cellular identities, distribution patterns and day/night expression changes in PER1, PER2, CaBPs, and MT1 and MT2 melatonin receptors in the cerebellar cortex of a diurnal primate using conventional fluorescence and peroxidase-antiperoxidase immunocytochemical techniques. PER1 and PER2 immunoreactive (IR) cells were observed in the Purkinje cells of the cerebellum, and MT1 and MT2 receptors were localized around Purkinje cells in the Pj layer in Bergmann cells. This identity was confirmed by the S100β-IR of these cells. The highest expression of PER seen in the daytime analysis coincided with the highest expression of melatonin receptors. CaBPs showed day/night morphological and density changes in the cerebellar cortex. The presence of the same temporal variations in the expression of PER in the Pj neurons and in MT1 and MT2 receptors in Bergmann cells indicates a possible relation between these cells during the rhythmic processing of the cerebellum, in addition to the CaBP temporal morphological and density changes.

Circadian regulation of membrane physiology in neural oscillators throughout the brain

“…Arrhythmic animals with SCN lesions, however, no longer exhibit rhythmic clock gene expression, suggesting that the SCN and cerebellum have a hierarchical relationship (Rath et al., ). As there are no direct connections from the SCN to the cerebellum, the mechanism by which circadian rhythmicity in the cerebellum is entrained to the SCN or the LD cycle is unknown; however, several studies have hypothesized some form of hormone signaling (Guissoni Campos et al., ; Mendoza et al., ; Mordel et al., ). Interestingly, clock gene expression is localized to granule cells and Purkinje cells in mice (Rath et al., ).…”

“…Interestingly, clock gene expression is localized to granule cells and Purkinje cells in mice (Rath et al., ). In primates, however, PER1/2‐ir is expressed in the Purkinje cell layer (the primary output of the cerebellum), but not the granule or molecular cell layers, with higher expression during the day (ZT 10) compared to the night (ZT 19; Guissoni Campos et al., ). Bmal1 deletion specifically in granule cells renders expression of the majority of clock genes arrhythmic; however, circadian locomotor behavior is not significantly changed (Bering, Carstensen, & Rath, ).…”

Effects of Melatonin on Neurobehavior and Cognition in a Cerebral Palsy Model of plppr5−/− Mice

“…Luciana Pinato’s study showed that cerebellar can synthesize melatonin as a response to inflammation ( 23 ). Guissoni Campos, L. M. et al reported that the effects of melatonin on cerebellum may be related to sensorimotor and neuroprotection ( 60 ). It should be mentioned that melatonin is a neuroprotective drug when cerebellar cells are attacked.…”

Melatonin receptors and Per1 expression in the inferior olivary nucleus of the Sapajus apella monkey

“…The lack of rhythmicity does not rule out these receptors like targets in treating diseases involving the ION ( Stankov et al, 1994 ; Fraschini et al, 1999 ). Previously, these receptors had already been described in the cerebellum, another area known to be involved in motor control ( Mazzucchelli et al, 1996 ; Guissoni Campos et al, 2018 ). The presence of these receptors in this nucleus reinforces the possible melatonin participation in controlling circadian phenomena subserving motor performance ( Stankov et al, 1994 ), in addition to other functions already described ( Reiter et al, 2012 ; Cipolla-Neto et al, 2014 ).…”

“…Besides this, little was described as melatonin receptors and their relationship with clock genes in brain areas related to motor functions. Both receptors and clock genes were found in the cerebellum ( Guissoni Campos et al, 2018 ), where the maximal expression of melatonin receptors was found to coincide with that of Per proteins, base nuclei, and the substantia nigra ( Uz et al, 2003 , 2005 ; Christiansen et al, 2016 ).…”