Quantitative Ultrastructural Analysis of Differences in Exocytosis Number in Adrenomedullary Adrenaline Cells of Golden Hamsters Related to Time of Day, Pinealectomy, and Intracellular Region

Abstract

This research analyzed differences mainly in the incidence of exocytotic figures in adrenaline cells (A-cells) in pinealectomized (PX), sham-operated (SPX), and non-operated (NO) adult male golden hamsters, with the aim of determining whether these parameters change with the time of day and following pinealectomy, and whether intracellular regional differences exist in such changes. Animals acclimated to a standardized light:dark (LD) 12:12 photoperiod were sacrificed at 11 h after the onset of light (L-11h) and 1 h after the onset of darkness (D-1h) (8 animals/group/time) at 28 days postoperation. The adrenal medullas were examined and analyzed morphometrically by electron microscopy. The number of exocytoses per unit length (NEL) and the exocytosis index (a rough index of the number of exocytoses per cell) were measured in PF (perivascular-space-facing) and non-PF plasma membranes. NEL increased from L-11h (NO: 0.040 +/- 0.010, mean +/- SE) to D-1h (0.078 +/- 0.012) in all three experimental groups (ANOVA: P less than 0.005), showing over fourfold higher levels in PF than in non-PF membranes. NEL in PF membranes in PX animals showed higher levels than those in NO and SPX animals (P less than 0.025), but in non-PF membranes, no differences owing to time of day or surgery were seen. Exocytosis indices were (1) higher at D-1h than at L-11h in all three experimental groups (P less than 0.005), (2) similar in PF and non-PF membranes in control groups, and (3) higher in PF membranes in the PX group than in either non-PF membranes or PF membranes in control groups. In conclusion, the exocytosis number in A cells changes in relation to time of day, rising in early dark phase, and its rise following pinealectomy can be seen only in PF membranes.

Quantitative Cytological Analysis of Functional Changes in Adrenomedullary Chromaffin Cells in Normal, Sham‐Operated, and Pinealectomized Rats in Relation to Time‐of‐day: II. Nuclear‐Cytoplasmic Ratio, Nuclear Size, and Pars Granulosa of Nucleolus

“…Unique effects of sham operations like those reported by us in the adrenal medulla [Kachi et al, 1979[Kachi et al, , 1980a[Kachi et al, ,b, 1984[Kachi et al, , 1985a were also seen in the present study, especially evident as dampening of 24-h rhythmic changes in the nuclear size and as suppressive effects on the frequency of granulated nucleoli. Concerning the size of nuclei of the adrenomedullary cells, Weiss et al [ 19801 reported that lesions in the lateral hypothalamus or in the lateral mamillary nuclei resulted in a decrease in nuclear size.…”

“…We previously reported 24-h rhythmic changes in some quantitative morphological features of nucleoli in A-and N-cells, exocytosis in A-cells and nerve endings on A-and N-cells in Holtzman rats and Golden Hamsters and effects of pinealectomy and/or sham-operations on them [Kachi, 1983;Kachi et al, 1979Kachi et al, , 1980aKachi et al, ,b, 1984Kachi et al, , 1985a. In the present study, we further investigated quantitatively the nuclear-cytoplasmic (N/P) ratio, nuclear size, and the pars granulosa of the nucleolus of the adrenomedullary A-and Ncells, using the same specimens as used in the previous studies.…”

Exocytosis in the antral gastrin cells of mouse, rat, and guinea pig after stimulation by carbamylcholine

“…Morphological evidence of exocytosis is difficult to capture in many endocrine and neuronal cells, because this process is probably very rapid and the granular contents may be immediately dispersed on their release. Many exocytotic figures have been reported in the adrenal chromaffin cells of the hamster, and convincing evidence of exocytosis has been demonstrated (Dinner 1967;Benedeczky and Somogyi 1975;Nagasawa 1977;Kachi et al 1985). This may reflect an unusual slowness of the process in the hamster, thereby allowing its detection by routine chemical procedures.…”

Exocytosis in Pheochromocytoma Cells after Exposure to a High Concentration of Potassium

“…1967;Benedeczky and Somogyi. 1975;Nagasawa, 1977;Kachi et al, 1985]. We first observed the clear evidence of exocytosis in the PC 12 cells after 1-min exposure to a high concentration of potassium medium.…”