Effects of sympathicolytic and sympathomimetic drugs on pineal ultrastructure in the domestic pig

Abstract

The effects of a 4-day administration of two sympathicolytic (alpha-methyl-p-tyrosine, propranolol) and three sympathicomimetic (clorgyline, isoproterenol, dobutamine) drugs on the ultrastructure of the pineal gland in the domestic pig were examined. The morphological changes in the pinealocytes of the experimental groups mainly concerned cytoplasmic dense bodies, primary lysosomes, multivesicular bodies, dense core vesicles, and smooth endoplasmic reticulum. These structures seemed to be under direct or indirect control by the adrenergic nervous system. The relative volume of dense bodies in pinealocyte perikarya increased after administration of alpha-methyl-p-tyrosine as well as propranolol and decreased on treatment with clorgyline. The decrease in the relative volume of primary lysosomes in pinealocyte perikarya was noted in pigs treated with clorgyline and isoproterenol. The number of multivesicular bodies in pinealocyte perikarya decreased after administration of alpha-methyl-p-tyrosine. The numerical density of dense core vesicles in pinealocyte perikarya increased after treatment with clorgyline. Administration of isoproterenol and clorgyline resulted in the presence of wide cisterns of smooth endoplasmic reticulum. Narrow cisterns of this form of endoplasmic reticulum and lamellar whorls were observed after treatment with alpha-methyl-p-tyrosine in pinealocytes with large dense bodies. The presence of multilamellar structures was a characteristic feature of the pinealocytes of pigs treated with isoproterenol and dobutamine. Administration of alpha-methyl-p-tyrosine and clorgyline resulted in the appearance of pinealocytes which differed in number, size, and structure of dense bodies.

Adrenergic Activation of Melatonin Secretion in Ovine Pineal Explants in Short-Term Superfusion Culture Occurs via Protein Synthesis Independent and Dependent Phenomena

“…The adrenergic stimulation had no effect on AA-NAT activity measured using 10 mM of tryptamine, but the increase in activity was noted in the assay performed at 0.1 and 1 mM of this substrate. The regulation of the pineal hormone secretion solely via protein synthesis independent mechanism is probably related to the specific subcellular organization of pig pinealocytes [44, 45] and it is reflected in the diurnal patterns of plasma melatonin level [46, 47]. …”

Adrenergic control of pinealocyte chondriome – an in vitro study

“…The results of pharmacologic studies are less conclusive. The administration of amiflamine (MAO-A inhibitor), a drug which increases the content of endogenous NE (Oxenkrug et al 1991), to immature pigs increased the relative volume of mitochondria in pinealocytes , whereas a similar treatment with clorgyline (another MAO-A inhibitor) has no effect on the relative volume of mitochondria in these cells (Lewczuk and Przybylska-Gornowicz 1997). Changes in mitochondria in pig pinealocytes were not observed after the intravenous administration of isoproterenol, dobutamine, propranolol, and α-methyl-p-tyrosine (Lewczuk and Przybylska--Gornowicz 1997).…”

“…A point count analysis (Weibel 1979) was employed, as characterized in detail in our previous work (Lewczuk and Przybylska-Gornowicz 1997), to estimate the relative volume (expressed as the percent of cytoplasm of pinealocyte perikaryon) and the numerical density of mitochondria (expressed as the number of mitochondria per 60 μm 2 ). The percentages of mitochondria occurring in the form of small isolated particles or complexes (networks and extended filaments) were also determined.…”

Diagnosis and Management of Pineal Germinoma: From Eye to Brain

“…The pineal gland is in contact with the pineal recess and dorsal supraspinal recess containing the choroid plexus of the third ventricle. 15 While Vollrath in 1981 describes 6 anatomical variants of pineal gland have been identified in mammals based on shape, spatial relationship to the third ventricle, and parenchymal continuity, 16 variants Type A -in which the pineal gland is round or oval, proximal to the posterior edge of the diencephalon, and often in the vicinity of the third ventricle in contact with cerebrospinal fluid -and Type ABC -in which the pineal gland is elongated into a rod-shape and extending more towards the cerebellum -are most common in humans. 15,16 The pineal has a ventro-caudal relationship to the upper aperture of the cerebral aqueduct, where anterior extension of the germinoma can result in hydrocephalus by blocking the aqueduct.…”