The invagination complex in nerve endings on adrenomedullary adrenaline cells: quantitative ultrastructural description, and analysis of changes with time-of-day and their modification by sham-surgery and pinealectomy

An electron microscopic study on nerve endings on adrenomedullary adrenaline cells in golden hamsters: position, size and changes due to pinealectomy

Effects of sham-pinealectomy and pinealectomy on preganglionic nerve endings on adrenomedullary adrenaline cells were investigated electron microscopically. Adult male golden hamsters from the normal, sham-pinealectomy and pinealectomy groups maintained under 24 h light-dark cycle and constant temperature were used at 28 days after surgery. From conventional electron microscopic specimens, montage photographs made of the adrenaline cell region at a magnification of x 11,000 were used for qualitative and quantitative electron microscopic analyses in 14 animals in each experimental group. The preganglionic nerve endings were localized mainly in the following three sites: the basal lamina part, the follicular lumen-junctional intercellular part, and the adrenaline cell-invaginated part. In the latter two parts, nerve endings and fibers had no envelope frequently, and in the former two parts, nerve endings sometimes showed the invagination complex. The frequency of nerve endings was highest in the follicular lumen-intercellular part, next highest in the basal lamina part and lowest in the A cell-invaginated part. The frequency of nerve endings in the basal lamina part was lower in the pinealectomy group than in the sham-pinealectomy group (P < 0.021), and those in the other two parts showed opposite changes, more evidently in the A cell-invaginated part. Nerve ending profiles in the adrenaline cell-invaginated part--which displayed a more rounded shape--increased in size in the pinealectomy group (longer diameter: P < 0.04; shorter diameter: P < 0.05). In conclusion, preganglionic nerve endings in the adrenal medulla of the golden hamster show differential morphological changes following PX depending on the intracellular part of A cells.

Rough endoplasmic reticulum in the adrenaline and noradrenaline cells of the adrenal medulla: effects of intracranial surgery and pinealectomy

Adrenal medullas in 53-day-old rats of the nonoperated (NO) group (n = 31), the sham-operated (SPX) group (n = 35) and the pinealectomized (PX) group (n = 38) were examined electron microscopically 14 days after surgery. Cell profiles showing solitarily and sparsely distributed rough endoplasmic reticulum (RER) were most frequent in the PX group (daily mean: 66.9%, 427/638), less in the NO (56.0%, 336/600), and least in the SPX (48.5%, 297/612) in adrenaline (A) cells (chi 2-test: P less than 0.001), while most frequent in the NO group (68.8%, 340/494), less in the PX (64.3%, 303/471), and least in the SPX (57.4%, 256/446) (P less than 0.005) in noradrenaline (N) cells. Individual variation was less in A cells than in N cells. Cell profiles showing a large accumulation of RER was more frequent in A cells (NO:8.5%, SPX:13.1%, PX:7.7%) than in N cells (NO:2.8%, SPX:4.5%, PX:4.7%) (controls: P less than 0.001). Sham pinealectomy increased a large accumulation of RER in A cells (P less than 0.02) and a small aggregation of RER in N cells (P less than 0.005) with opposite effects of pinealectomy (P less than 0.005, P less than 0.025). Pinealectomy decreased a small aggregation of RER without effects of sham pinealectomy in A cells (P less than 0.001).

CONCLUSIONS

(1) Accumulation or aggregation of RER in adrenomedullary chromaffin cells was influenced from the pineal gland either as or without effects of intracranial surgery, and (2) RER in adrenomedullary chromaffin cells showed differences due to cell types.

Effects of pinealectomy on the mitotic activity of adrenomedullary chromaffin cells in relation to time of day

The frequency of mitoses of adrenaline (A) cells and noradrenaline (N) cells in the adrenal medulla of nonoperated (NO), sham-operated (SPX), and pinealectomized (PX) male, 53-day-old Holtzman rats (n = 133) was investigated by means of light microscopy. Animals were killed at eight time points during a standardized 24-h light-dark (12:12) cycle 14 days after surgery. Mitotic indices (n/1,000) were determined in sections of adrenal medulla fixed with glutaraldehyde and OsO4. Overall frequency of mitoses was extremely low (mitotic index: 0.73 = 115/157,223). Daily mean mitotic index was maximum in A cells (0.83) and minimum in N cells (0.52) of PX group but did not show statistically significant differences between cell types or experimental groups. Neither cell type in NO animals showed 24-h changes in mitotic index, but cells in SPX animals did, with highest value in the late dark phase and lowest in the late light phase, when values of two cell types were combined (P less than 0.01-0.001). In PX animals, mitotic index followed a similar but more distinct 24-h change in A cells (P less than 0.009), but not in N cells, resulting in different time-of-day changes between two types of cells (P less than 0.01-0.05). The mitotic index was higher in PX than in control (NO and SPX) animals in the middark phase (P less than 0.05) and lower in operated (SPX and PX) than in nonoperated (NO) animals from late light to the early dark phase, suggesting that the latter was possibly due to a residual effect of the surgery. These results are consistent with the interpretation that the pineal has an inhibitory action on A cells and may coordinate the two types of cells in their mitotic activity, especially in the middark phase of the daily cycle.

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

Adrenaline(A)- and noradrenaline(N)-cells in the adrenal medulla of nonoperated (NO), sham-operated (SO), and pinealectomized (PX) male rats (n = 125) were investigated by quantitative electron and light microscopy. Animals were killed at eight time points during a standardized 24-h, light-dark (12:12) cycle 14 days after surgery. Nuclear-cytoplasmic (N/P) ratios, diameters of nuclei, and the frequency of nucleoli showing a large amount of pars granulosa (granulated nucleoli), were the primary characteristics studied. Major findings include the following: 1) The frequency of low N/P ratios over a 24-h period tended to be higher in PX animals than in controls in A-cells, as shown in large cell profiles (P less than 0.02); but such a tendency was not apparent in N-cells. Daily mean nuclear diameters were similar among the three experimental groups. 2) The 24-h changing pattern of phase relations in the frequency of low N/P ratio and nuclear size differed between A- and N-cells in NO and SO but not in PX animals. 3) The frequency of granulated nucleoli in A-cells was much higher in PX animals than in NO and SO animals throughout a 24-h period (P less than 0.018), especially from the late light to early dark phase (P less than 0.003), and higher in A-cells than in N-cells generally (P less than 0.0009). Pinealectomy thus caused increases in the cytoplasm and in the pars granulosa of the nucleolus in many A-cells; changes in N-cells were less apparent. This suggest a disturbed balance and coordination between A- and N-cell systems of adrenal medulla following pinealectomy.

Quantitative cytological analysis of functional changes in adrenomedullary chromaffin cells in normal, sham-operated, and pinealectomized rats in relation to time of day: III. Nuclear density

The sizes of adrenaline (A) and noradrenaline (N) cells in the adrenal medulla of nonoperated (NO), sham-operated (SPX), and pinealectomized (PX) male rats (n = 126) were investigated by quantitative light microscopy. Animals were killed at eight time points during a standardized 24-h, light-dark (12:12) cycle 14 days after surgery. Nuclear densities were measured in semithin sections of epon-embedded specimens, initially fixed with glutaraldehyde and OsO4. Major findings are as follows. 1) The mean size of adrenomedullary A cells throughout 24 h (P less than 0.001), especially in the dark phase (P less than 0.001) but not in the light phase, was larger in PX animals than in NO and SPX animals. There were no statistically significant differences in the size of N cells among the three experimental groups in either the dark phase or the light phase. 2) The sizes of A and N cells showed time-of-day changes in the NO and the SPX animals but not in the PX animals. The temporal relationship of 24-h changes in the cell size tended to be different between A and N cells in the NO and the SPX animals but not in the PX animals. 3) The cell size was apparently larger in A cells than in N cells in each experimental group. Pinealectomy thus caused hypertrophy of A cells, especially in the dark phase, but not apparently hypertrophy of N cells. Concerning the pinealectomy effects in relation to the time of day, the results support the hypothesis of pineal action being phase-tuning and coordinating of at least some circadian systems.

Influence of age and splanchnic nerve on the action of melatonin in the adrenomedullary catecholamine content and blood glucose level in the avian group

A single intraperitoneal (IP) melatonin injection (0.5 mg/100 g body wt.) caused an increase in norepinephrine (NE) fluorescence and elevation of NE content in newly-hatched pigeons (Columba livia), but a reduction of NE fluorescence and depletion of NE content in the adrenal medulla of newly-hatched crows (Corvus splendens) after 0.5 h of treatment. In contrast, in adults melatonin caused increase in NE fluorescence and elevation of NE content only in the parakeet (Psittacula krameri). Half an hour of IP melatonin treatment (0.5 mg/100 g body wt.) induced release of epinephrine (E) from the adrenal medulla of newly-hatched pigeon and parakeet. In contrast, in the adults melatonin caused more than a two-fold increase in E in the pigeon, and a significant increase in the crow. Single IP melatonin injection (0.5 mg/100 g body wt.) caused hypoglycemia in the newly-hatched parakeet and adult pigeon, and hyperglycemia in newly-hatched pigeon after 0.5 h of treatment. Melatonin failed to regulate glucose homoeostasis in newly-hatched and adult crow. Splanchnic denervation of the left adrenal gland was performed in the adult pigeon. The right adrenal served as the innervated gland. Melatonin-induced modulation of catecholamines following a single IP injection (0.5 mg/100 g body wt.) revealed significant increases in NE fluorescence and NE content at 4 and 12 h after treatment in the denervated gland only, which gradually approached normal levels 9 days after treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of melatonin on adrenomedullary dopamine-beta-hydroxylase activity in golden hamsters: evidence for pineal and dose dependencies

Pineal influence in the control of adrenomedullary function in golden hamsters was investigated by examining changes in adrenal dopamine-beta-hydroxylase (DBH) activity following pinealectomy, either alone or in combination with melatonin administration. Adult males acclimated to an LD 14:10 photoperiod were distributed in five experimental groups: intact controls (NO), sham-pinealectomized (S), sham-pinealectomized with black plastic shielding of the pineal region, pinealectomized (PX), and pinealectomized with the operated region shielded. Animals representing all of these groups were injected (between L11 and L11.75) with either vehicle, or a low dose (25 micrograms) or a high dose (2,500 micrograms) of melatonin daily for 28 days, after which they were killed, and the adrenals were collected for assay of DBH activity by means of a sensitive radioenzymatic method. We found that PX + vehicle led to increased (P less than .05) adrenal DBH activity in comparison with either NO or S groups; daily 25 micrograms of melatonin resulted in lowered DBH activity in the NO group when compared with NO + vehicle (P less than .001) or S + vehicle (P less than .001) groups; PX + 25 micrograms melatonin reversed the action of 25 micrograms melatonin in the NO + 25 micrograms group; 2,500 micrograms melatonin was without effect on adrenal DBH in any of the injected surgical groups. These results show an inhibitory pineal influence on adrenal DBH activity, and that this was dose dependent.(ABSTRACT TRUNCATED AT 250 WORDS)

Quantitative ultrastructural analysis of differences in exocytosis number in adrenomedullary adrenaline cells of golden hamsters related to time of day, pinealectomy, and intracellular region

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: I. Nucleolar size

Adrenaline (A)- and noradrenaline (N)-cells in juxtacortical and central areas of adrenal medullas of nonoperated, sham-operated, and pinealectomized male rats (n = 125) were investigated by quantitative electron and light microscopy. Animals were killed at eight time points during a standardized 24-h, light-dark (12:12) cycle 14 d after surgery. Diameters of nucleoli (n = 9,600) and the nucleolar margination rate were studied chiefly by light microscopy. Major findings include the following: Twenty-four-hour changes occurred in nucleolar diameters in adrenomedullary chromaffin cells in nonoperated animals, with the peak in the late dark phase (X +/- SD, A-cells: 1.29 +/- 0.06 micron; N-cells; 1.23 +/- 0.05 micron) and the minimum in the mid-light (A-cells: 1.16 +/- 0.04 micron) or early dark (N-cells: 1.14 +/- 0.03 micron) phase. These changes were markedly dampened (diminished) in sham-operated animals. Since this dampening of time-of-day changes after sham-operations was not seen in A-cells after pinealectomy, mediation by the gland of this dampening is suggested. Pinealectomized animals showed 24-h changes in nucleolar diameters, but these changes differed from those of nonoperated controls in their temporal and phase relations. For example, there was phase advance in A-cells in the juxtacortical area and desynchronization in N-cells. Furthermore, rhythm amplitude was slightly increased in A-cells and slightly decreased in N-cells after pinealectomy. A- and N-cells differed from each other consistently and significantly in the quantitative morphology of their nuleoli and nuclei, and slightly in the patterns of their time-of-day changes in nucleolar size. Nucleolar size usually showed a tendency for a regional gradient, decreasing slightly from periphery toward the center. These observations contribute to our understanding of the chronobiology and functional relations of adrenomedullary chromaffin cells, and of the effects of pinealectomy and sham operations upon this system.