Effect of magnetic field on pineal gland volume and pinealocyte size in the rat

Biological effects of rotating magnetic field: A review from 1969 to 2021

As one of the common variable magnetic fields, rotating magnetic field (RMF) plays a crucial role in modern human society. The biological effects of RMF have been studied for over half a century, and various results have been discovered. Several reports have shown that RMF can inhibit the growth of various types of cancer cells in vitro and in vivo and improve clinical symptoms of patients with advanced cancer. It can also affect endogenous opioid systems and rhythm in central nerve systems, promote nerve regeneration and regulate neural electrophysiological activity in the human brain. In addition, RMF can influence the growth and metabolic activity of some microorganisms, alter the properties of fermentation products, inhibit the growth of some harmful bacteria and increase the susceptibility of antibiotic-resistant bacteria to common antibiotics. Besides, there are other biological effects of RMF on blood, bone, prenatal exposure, enzyme activity, immune function, aging, parasite, endocrine, wound healing, and plants. These discoveries demonstrate that RMF have great application potential in health care, medical treatment, fermentation engineering, and even agriculture. However, in some cases like pregnancy, RMF exposure may need to be avoided. Finally, the specific mechanisms of RMF's biological effects remain unrevealed, despite various hypotheses and theories. It does not prevent us from using it for our good.

Magnetoreception attributed to the efficacy of light therapy

A group of specialized photoreceptors are suggested to amplify the weak interaction of the geomagnetic field with a single electron spin to the level of photon detection, resulting in a modulation of the response to light. Under exposure to rotating magnetic field, the size of pinealocytes is bigger at night than during the day in spring, but there is no day-night difference in autumn. Specialized photoreceptors are hypothesized to modulate the response of the photoreceptive system to light, and the pineal response to a magnetic stimulus, in patients with winter seasonal affective disorder (SAD). This could explain why some winter SAD patients show excessive sensitivity to light in winter.

Quantitative light microscopic study on the heterogeneity in the superficial pineal gland of the rat

BACKGROUND

The previous results regarding regional and day-night differences in pinealocyte size in rats are conflicting. The relationships between these differences and the vascularity and sympathetic innervation have scarcely been investigated.

METHODS

Wistar-King rats, kept under light/dark 12:12, were killed at midday or midnight in October. The nuclear density of pinealocytes in the superficial pineal was measured on the dorsoperipheral, dorsocentral, ventroperipheral, and ventrocentral regions at distal, middle, and proximal levels at daytime and nighttime. The total area of blood vessels per unit area at daytime and nighttime and total length of tyrosine hydroxylase (TH)-immunoreactive fibers per unit area at daytime were determined on the same regions at the same levels.

RESULTS

Pinealocyte size was larger toward the distal levels and in the periphery than in the center at any level. The area of blood vessels and length of TH fibers were also larger toward the distal levels; the former in the ventral region and the latter in the dorsal and ventral regions were larger in the periphery than in the center. Ventral pinealocytes, but not dorsal ones, showed day-night changes in size. Prominent day-night rhythms in area of blood vessels occurred in the ventral region, where TH fibers were more abundant than in the dorsal region.

CONCLUSIONS

Pinealocyte size shows the distal to proximal and peripheral to central gradients, which may be related to the differential distribution of blood vessels and sympathetic fibers. Since pinealocytes and blood vessels, showing prominent day-night changes in size, are localized in the more richly innervated regions, sympathetic fibers may play an important role in controlling these rhythms.

Regional differences in the pineal gland of the cotton rat, Sigmodon hispidus: light microscopic, electron microscopic, and immunohistochemical observations

Light microscopic, electron microscopic and immunohistochemical observations of the various portions of the pineal gland of the cotton rat (Sigmodon hispidus) were made. The volume of the proximal half occupied about 30% of the whole organ, and pinealocytes were slightly smaller in size in the proximal portion than elsewhere. The distal and intermediate portions contained few interstitial cells and numerous astrocytes, but the proximal portion lacked interstitial cells and had more abundant astrocytes than elsewhere. Astrocytes, which were immunoreactive for glial fibrillary acidic protein, mainly lined the pericapillary spaces in the distal and intermediate portions, but in the proximal portion these cells often surrounded isolated or groups of pinealocytes. In the distal and intermediate portions, abundant sympathetic fibers and less numerous non-sympathetic, peptidergic fibers were mainly localized in the pericapillary spaces; these fibers were sparsely distributed in the parenchyma close to interstitial cells or astrocytes. In the proximal portion, non-sympathetic fibers were scarce and sympathetic fibers were distributed abundantly and almost exclusively in the parenchyma. Most of the sympathetic fibers were adjacent to astrocytes and, occasionally, made specialized contact with them. Fenestrae in the capillary endothelium were numerous in the distal portion but absent in the proximal portion. Thus, marked differences in structure existed between the distal and proximal portions of the pineal gland of the cotton rat suggesting that both portions are functionally dissimilar. In addition, the present study indicates that the proximal portion of the cotton rat was well developed and showed morphological features similar to the deeply situated pineal glands of other mammals.