Pineal Effects on Adrenal Medulla, Area postrema and Brain Water Content in Relation to Intracranial Surgery

Abstract

We aimed to explore whether and how the pineal influences the adrenal medulla, the area postrema and the brain water content; and is influenced by sham pinealectomy (SPX) in its structures and melatonin secretion. Quantitative morphological methods were mainly used in rats and golden hamsters. Experimental results showed: (1) Pineal effects on the A cell system of the adrenal medulla were inhibitory to the synthesis and secretion of epinephrine into the perivascular space and stimulatory to the opioid synthesis, and augmented by SPX. Time-of-day changes were also influenced by SPX and PX. (2) The sizes of a part of the nuclei of nerve and glia cells in the area postrema and the brain water content increased by SPX depending on the presence of the pineal, suggesting the pineal’s stimulatory effects on these following SPX. (3) SPX caused morphological changes suggesting an increased activity of pinealocytes. However, corresponding consistent increases in plasma melatonin levels were not seen following SPX. Possible interpretations of these observations were discussed.

Interleukin-1β-Induced Increases of Plasma Catecholamine Levels in Rats: Enhancement by Superior Cervical Ganglionectomy

“…Previous electron microscopy studies showed that the pineal gland has an inhibitory effect on the adrenaline cell system of the adrenal medulla, thereby inhibiting the synthesis and secretion of adrenaline into the perivascular space [24,25]. The activity of adrenal phenylethanolamine-N-methyltransferase, which catalyzes conversion of noradrenaline to adrenaline, was reduced by melatonin in golden hamsters [26].…”

Effects of intracranial surgery on pineal lipid droplets, on other structures, and on melatonin secretion

“…Intracranial invasion can cause a marked disturbance of intracranial environment, which has a strong impact on nociceptive, autonomic, neuroendocrine, and/or emotional response networks in the central nervous system, and melatonin receptors have been shown to exist in such responsive elements of the networks (for reviews see Kachi 1987Kachi , 2007Kachi et al 1997). Thus, it seems possible that the pineal-dependent IS effects are mediated by complex mechanisms which include the central autonomic network, limbic system, and/or regulatory system of the brain circulation.…”

“…On the other hand, from various comparative studies among normal non-operated (NO), sham-pinealectomy (SX), and pinealectomy (PX) groups, a possibility has gradually emerged that SX has its own effects on structures and functions in the adrenal gland and other organs or tissues (for reviews see Kachi 1987;Kachi et al 1997). Curiously, and interestingly, SX resulted in a decrease in plasma and adrenal corticosterone (Dill 1961) and exerted inhibitory or dampening effects on the main functional structures and 24-h rhythms of adrenomedullary chromaffin cells and the preganglionic neurons innervating them (Kachi et al 1979(Kachi et al , 1985Irie and Kachi 1999; for a review see Kachi et al 1998) and stimulatory effects on opioid synthesis-related structures and immunoreactivity in adrenomedullary chromaffin cells (Kachi et al 1992(Kachi et al , 1993Kimura and Kachi 1996).…”

“…Curiously, and interestingly, SX resulted in a decrease in plasma and adrenal corticosterone (Dill 1961) and exerted inhibitory or dampening effects on the main functional structures and 24-h rhythms of adrenomedullary chromaffin cells and the preganglionic neurons innervating them (Kachi et al 1979(Kachi et al , 1985Irie and Kachi 1999; for a review see Kachi et al 1998) and stimulatory effects on opioid synthesis-related structures and immunoreactivity in adrenomedullary chromaffin cells (Kachi et al 1992(Kachi et al , 1993Kimura and Kachi 1996). SX also increased the water content of the brain (Kachi et al 1997) and reduced the blood flow through capillaries in a region, the area postrema, of the brain (Kudou et al 2001). Because these effects were often reversed by PX or constant light, SX effects were considered to be pineal-dependent.…”

“…SX is intracranial surgery (IS) which includes tissue injury, slight bleeding, and leak of the cerebrospinal fluid, and can cause changes in brain circulation and weight, pain, and unpleasantness (Edvinsson et al 1993;Ganong 2005). Thus, it seems likely that SX exerts complex effects on nociceptive, autonomic, neuroendocrine, and/or emotional response mechanisms in the brain and peripheral tissues (for reviews see Kachi 1987Kachi , 2007Kachi et al 1997). Unique SX effects may be derived from such special situations, at least in part.…”