Differences between adrenomedullary adrenaline and noradrenaline cells: quantitative electron-microscopic evaluation of their differential cellular association with supporting cells

Quantitative differences in cellular association of adrenomedullary chromaffin cells with other types of cells, mainly supporting cells, were studied. Adrenaline (A) and noradrenaline (NA) cells were compared. Electron micrographs (12000 x) of profiles of A and NA cells, bordering against other types of cells, were used for quantitative evaluation. Supporting cells constituted the majority of the non-chromaffin cell types. Occurrence frequencies of chromaffin cells contiguous with other types of cells were: (1) higher for A cells (68.9%, 199/289) than for NA cells (11.0%, 34/309) in case of small contact regions (chi 2-test: P < 0.001), and (2) higher for NA cells (68.3%, 211/309) than for A cells (9.7%, 28/289) in case of extended contact regions (P < 0.001). In conclusion, the extent of cellular association with supporting cells was remarkably lower in A cells than in NA cells. Such an arrangement is likely to be appropriate for the extensive, homogeneous control and amplified response characteristic of A cells, and for the close range, complex control and more diverse responses characteristic of NA 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.

Changes with darkness in regional brain 5-hydroxytryptamine and 5-hydroxyindole acetic acid: local differences with pinealectomy, sham surgery, and melatonin

Brain regional 5-HT (5-hydroxytryptamine) and 5-HIAA (5-hydroxyindole-3-acetic acid) concentrations in male LE rats at three times were measured by a fluorescence method, to evaluate effects of intracranial surgery and administration of melatonin on the changes in these compounds during the first part of the dark phase of the daily cycle in a fixed 12:12 L:D photoperiod. Early surgical pinealectomy or a similar but sham intracranial surgery, led to delay in darkness-associated fall in frontal cortical and striatal 5-HT. A single melatonin injection two hours before darkness, reversed this effect in frontal cortex but not striatum. Melatonin's specification of action in this experiment is interpreted as residing in specific timing of release and/or administration, rather than in either a fixed or general basis neurochemically.

Effects of thyroid hormone on light/dark melatonin synthesis and release by young and maturing rat pineal glands in vitro

Synthesis and release of melatonin were studied in pineal explants from 14- (young) and 60-day-old ('maturing') male Long-Evans rats with or without added thyroid hormone, triiodothyronine (T3), at or near physiological levels and under light and dark conditions. Incubation for 6 hr (1200-1800) was in a synthetic medium; melatonin was measured by radioimmunoassay (RIA). In light, T3 increased melatonin levels in pineal and medium of cultures from either young or maturing animals. In dark, T3 decreased melatonin levels in the pineals of either age, but was without significant effect on levels in the medium. Since it is known from other work that 14-day-old rat pineal glands do not yet have a complete sympathetic innervation system, it is here doubly evident that T3 can modulate directly pineal synthesis and release of melatonin, and may not depend upon a mature sympathetic innervation. Light in the studied conditions was permissive from the stimulatory action of T3 on pineal synthesis and release of melatonin in vitro.

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.

Developmental changes in hypothalamic melatonin levels of male rats

Hypothalamic melatonin levels of Long-Evans male rats were studied at three ages (25, 55-60 and 90 days), at four times of the day in the autumn (6:00, 12:00, 18:00 and 24:00), and at two times (12:00 and 24:00) in the spring using radiommunoassay. Melatonin levels increased markedly at noon at 55-60 days of age, compared with the levels at the same time of the day at 25 and 90 days. This increase persisted in autumn and spring. The 24-hr pattern in hypothalamic melatonin was the inverse of that in the pineal, with the levels at noon higher than those at midnight. This pattern was detectable at 25 days of age although the difference in melatonin between 12:00 and 24:00 hr was not great. The day/night difference was prominent by 55-60 days of age and disappeared by adulthood (90 days). This 24-hr pattern was similar in spring and autumn in the three ages studied. Although in the 55-60-day-old group the melatonin ratio (noon/midnight) was the same in autumn and spring, the absolute levels of melatonin in spring were significantly lower. The findings are consistent with the general concept of a modulatory role of melatonin in control of hypothalamo-hypophyseal GnRH and gonadotropin function, and the timing of the developmental maturation of this neuroendocrine axis. Demonstration of the mechanism of melatonin's action at the hypothalamic level will be facilitated by further definition of quantitative developmental changes.

Lower tryptophan:phenylalanine ratios in culture media increase medium: pineal melatonin ratios in early dark but not late light phase

Pineals from male Long-Evans rats (60-65 days old; adapted to a 0700-1900 photoperiod) were cultured for 6 h either in light (1200-1800) or in dark (1800-2400). The objective was to ascertain the effects of tryptophan (trp) and phenylalanine (phe) levels and ratios in the culture medium on melatonin levels in the pineals and their respective media. Total culture (pineal + medium) melatonin levels, determined by RIA, were similar under all conditions. However, in cultures during the early dark phase (1800-2400) lower trp:phe ratios in the medium led to lower pineal:medium ratios of melatonin content. In cultures during the late light phase (1200-1800) the trp:phe ratio had little impact on the pineal:medium distribution of melatonin. Trp:phe ratio rather than absolute level of either amino acid appeared responsible for this effect. Functionally this means that during early dark phase, but not late light phase, movement of melatonin from cultured pineal to medium is progressively facilitated by lower trp:phe ratios. It remains to be determined to what extent darkness per se and/or endogenous pineal rhythmic mechanisms have a permissive role in the action of trp:phe ratio on pineal melatonin release. A melatonin compartmentalization/release effect of these or other amino acids, or their ratios, has not been reported previously and may possibly contribute to mechanisms for melatonin's transport or release at night.

Spontaneous continuous release of spermatozoa and its predawn surge in male passerine birds

Spontaneous, continuous release of morphologically normal spermatozoa occurs in males of species of passerine (order Passeriformes) birds that were examined. It was demonstrated and studied quantitatively in temporarily captive and isolated house sparrows and house finches by means of repetitive cloacal lavages and extraction of excreta. It is suggested that this phenomenon could be exploited to facilitate comparative and quantitative evaluations of release of spermatozoa in relation to diverse environmental, physiological, and social factors.

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)

Double isotopic method using dansyl chloride for the determination of GABA in rat C6 astrocytoma cell cultures

Methods are described for the quantitative measurement of GABA in culture. The method can be adapted to any amino acid or dansyl-chloride-reactive species. The sensitivity and selectivity of the procedure result from the double isotopic design in which (14C)-labeled internal standard was added to the samples before reaction with (3M)-labeled dansyl chloride. Values obtained by ion-exchange amino acid analysis of cultures agree closely with the values obtained by the double isotopic method. This method is sensitive enough to measure GABA intracellularly and the condition medium.

Effects of melatonin implants on structures and behaviors of the house finch (Carpodacus mexicanus) eye

This study aimed to determine the extraretinal effects of melatonin upon the eyes of an avian species, the House Finch (Carpodacus mexicanus). Twelve birds (full-grown, second-year males) each received a Silastic tubing intraperitoneal implant, six containing melatonin (average release = 24 micrograms/d/bird; = M birds) and six being empty (= C birds). Microscopic study of pupillary and palpebral behaviors during the final week demonstrated lesser pupillary diameters and interpalpebral distances in M birds under all test conditions. These effects could have diminished mean light levels reaching parts of the retina. Characteristics of the relative miosis and ptosis of M birds resemble signs in some CNS disorders, such as altered inhibition of the Edinger-Westphal nucleus, and especially lesions in, or lowered activity of, higher sympathetic centers (a subtype of Horner's syndrome). Weights of eyes and their parts were the same in M and C birds, contrasting with previously reported results from male Golden Hamsters, possibly due to species differences and/or preexperimental attainment of full growth in the finches. Effects of melatonin on pupillary and palpebral behaviors, demonstrated here for the first time, foster caveats for simplistic experimental designs and interpretations with melatonin when sensory-neural-behavioral interactions are affected. Quantitative changes in pupillary and palpebral behaviors may, nevertheless, provide a window for monitoring central actions of melatonin in living test subjects in chronic studies.

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.

Quantitation of ultrastructural twenty-four-hour changes in pineal nuclear dimensions

An ultrastructural stereological analysis was made of the nucleus in pinealocytes of 28 male Fischer rats sampled at seven times in a light:dark 12:12 photoperiod cycle. Comparisons of the data from the seven times, in relation to daily means, showed variations in mean nuclear cross-sectional surface area of +/- 16%, and in mean nuclear perimeter of +/- 10%. Peaks in both nuclear dimensions occurred at the middle of the light period and were coincident with the presence of elaborate nuclear configurations and deep indentations. At 2330 and 0430 (1 and 6 h after lights off) nuclear folding was generally less complex. Mitochondria were found in close association with the nuclear folds. Forty percent of nucleoli were marginated at all of the sampling times, except at 1130 (1 h after lights on) and at 2330 (1 h after lights off), when 50% and 35%, respectively, were marginated.

Seasonal changes in glycogen level and size of pinealocytes of the white-footed mouse, Peromyscus leucopus: a semiquantitative histochemical study

Glycogen level in and size of pinealocytes of the feral, white-footed mouse Peromyscus leucopus, were studied by a semiquantitative histochemical method to determine whether seasonal changes exist in them under natural conditions, what temporal pattern they exhibit, and whether 24-hour changes in these parameters exist in different seasons, as shown in the laboratory dd-mice. Marked seasonal changes were seen in both glycogen levels and nuclear densities (ANOVA p less than 0.005). The size of pinealocytes at 09:00 to 10:00 showed one peak (and nadir) seasonal change, with the smallest size in winter (December and February) and a larger size in warmer seasons, with the maximum value in July. Glycogen level in pinealocytes at 09:00 to 10:00 showed bimodal seasonal changes, with lower levels in fall and spring and higher levels in winter and summer. In fall, a circadian trend in glycogen level in pinealocytes was seen, with a higher level at the end of the light period. In winter, the glycogen levels were very high at 09:00, 13:00, 17:00, and 21:00 examined and showed dampening of time-of-day differences. On the other hand, the size of pinealocytes followed a time-of-day change (P less than 0.005), being largest at 13:00 and smallest at 21:00. Thus, marked changes in quantitative structure and chemical activities, suggesting changes in functional activity, in pinealocytes were noted especially in severe, cold winter.

Increases in volume, fluid content, and lens weight of eyes following systemic administration of melatonin

Melatonin's effects were studied in male golden hamsters (Mesocricetus auratus) distributed among five surgical groups (nonoperated, sham-pinealectomized, sham-pinealectomized plus black plastic shielding of the pineal region, pinealectomized, and pinealectomized plus black plastic shielding of the pineal region) and three injection groups (vehicle only, 25 micrograms melatonin, and 2,500 micrograms melatonin). Injections (s.c.) were daily for 28 d at L11 to L11.75 in a (light:dark) L:D 14:10 artificial photoperiod. Animals (N = 112) were killed and dissected on the day after the last injection (at 55-65 d of age). None of the surgical procedures affected weights of eyes or their parts, nor did they influence the effects of administered melatonin on the eyes. Melatonin caused an increase in absolute and relative eye weight and an increase in fluid content of intraocular space. The magnitudes of these effects were positively related to melatonin dose. These same eyes had a progressively lower weight of nonlenticular tissues with low to high doses of melatonin, probably in relation to greater fluid content, and suspected increase in intraocular pressure. Lens wet and dry weights were significantly greater in animals receiving melatonin, but only at the high dose. These actions of melatonin are likely to be direct and are shown to not require the presence of the pineal. Experiments of other designs are suggested in order to determine whether the effects of the low, near physiological, dose of melatonin represent physiological actions of endogenous melatonin, synthesized and released within the eye. However, effects of large doses of melatonin on the eye are still noteworthy in relation to interpretation of experiments employing such dosages, and of disease states involving changes in intraocular pressure.

Effects of melatonin and control injections on pineal serotonin and norepinephrine: afternoon injections lower serotonin levels thirty-six percent at light-dark transition

Pineal weight and serotonin (5-HT) and norepinephrine (NE) contents were studied in male Sprague-Dawley rats that were maintained under controlled light:dark conditions (LD 14:10; lights on 0700-2100) and that received daily subcutaneous injections of either melatonin (20 micrograms in 0.1 ml per animal) or the same volume (0.1 ml) of vehicle alone, at one of two times (0800-0900 or 1800-1900). Animals were sacrificied at four times (1000, 1400, 2000, or 2300) on the day after the last of the 7 consecutive d of injection. Pineal glands were quickly weighed and then frozen for 5-HT and NE assay by the Maickel and Miller extraction and fluorescence methods. Pineal NE content showed differences related to time of day, in confirmation of early work. But no effects attributable specifically to melatonin were found. Melatonin also failed to affect pineal 5-HT content significantly. But injection of either melatonin or vehicle at 1800-1900 led to a reduction in 5-HT content averaging 36% when sampled at either 2000 or 2300, and in comparison with animals injected at 0800-0900. It is suggested that a stresslike or zeitgeberlike effect of injections within a critical period at the end of the daily light phase can cause an earlier-than-normal daily fall in pineal 5-HT content.

Low molecular weight pineal and cerebral fractions affecting insulin secretion in vitro

Studies were performed to examine the effects of various fractions of pineal gland origin upon rates of immunoreactive insulin release during short-term incubations of pancreatic islets from pinealectomized rats. Fractions of cerebral cortex were employed in control incubations. An ultrafiltrate of pineal extracts containing materials of molecular weight less than or equal to 1000 daltons stimulated insulin release while fractions of greater molecular weight were without effect. The stimulation of insulin release observed with the lower molecular weight pineal fraction was seen with both nonstimulatory (2 mM) and stimulatory (10 and 30 mM) medium glucose concentrations, but was abolished in the presence of 2,4-dinitrophenol (200 microM). Upon further fractionation of the low molecular weight pineal extract, fractions I (estimated molecular weight range 700-1000 daltons) and 11 (estimated molecular weight range 180-700 daltons) exhibited comparable stimulatory effects upon islet insulin release: similar effects were observed with cerebral cortical fractions in these molecular weight ranges. However, pineal fraction III (estimated molecular weight range less than 180 daltons) exhibited a striking inhibitory effect upon rates of insulin release compared to cerebral cortical fraction III. Potassium, dopamine, norepinephrine and epinephrine concentrations in both pineal and cortical tissue fractions were similarly low. We conclude that insulinotropic constituent(s) of similar molecular weight occur in pineal gland and cerebral cortex, and that the pineal insulinotropic activity stimulates active insulin secretion by the islets independently of concomitant stimulation by glucose; however, lower molecular weight insulinostatic constituent(s) are notable only in the pineal. It is suggested that mild hyperinsulinemia seen in pinealectomized rats under some circumstances may occur as a result of loss of the pineal insulinostatic factor(s).

The pinealocyte nucleolus. Ultrastructural and stereological analysis of twenty-four-hour changes

An ultrastructural and morphometric analysis was made of the nucleolar components in pinealocytes of 40 male Fischer rats sampled at eight times in an LD 12:12 photoperiod cycle. Comparisons of results from the eight times showed variation in estimated mean volume of the granular component of +/- 29%, and of the fibrillar component +/- 11%, in relation to daily means. Peaks in mean volume of total nucleolus and its granular component occurred at 1 h of light. Near maximal and minimal mean volumes of the fibrillar component both occurred during both light and dark. Fibrillar centers (nucleolar organizer regions) of different sizes were found at all sampling times. It is concluded that temporal patterns in 24-h changes in the nucleolar components are most prominent in the granular component, and are more complex than suggested by changes in total nucleolar size or mean dimensions, and than represented by a simple biphasic circadian rhythm. Examples of different stages in the migration of the granular component, and of possible sites of nucleo-cytoplasmic transfer of nucleolar material, are described.

Stimulatory effects of melatonin on ependymal epithelium of choroid plexuses in golden hamsters

Ependymal epithelial cells from the choroid plexuses (CPs) separately of lateral (I + II), IIIrd and IVth ventricles of male Golden Hamsters were studied by electron microscopy and morphometry. The 16 hamsters were distributed between three injections groups: vehicle only, 25 micrograms and 2500 micrograms melatonin (M) by subcutaneous injection daily at L11 to L11.75 in a LD 14:10 daily photoperiod. After 28 consecutive daily injections, animals were killed and the CPs were dissected, fixed and prepared for electronmicroscopy. Thirteen measures of the CP ependymal cells were made, by planimetry, morphometry or direct counting or linear measurement on the EM prints. Effects of melatonin occurred only on the cells from the lateral ventricles. Here M at high dosage caused cell swelling (averaging 50% increase in area), and other cellular changes were graded in relation to M dosage. These were increased (to 26%) in mitochondrial area per cell, and increased (to 50%) in length of apical microvilli. Since in other work the latter form a major locus of ouabain-sensitive Na+, K+-ATPase, it is suggested that M may possibly have a stimulatory effects on transport and related CSF secretory activities by these cells.

Melatonin's inhibition of pituitary, adrenal, testicular and accessory gland growth in male golden hamsters: pineal dependence and organ differences with shielding and intracranial surgery

Testes, accessory glands, pituitaries and adrenal glands from 101 male Golden Hamsters (55-65 days old) were weighed after 4 weeks of daily injections of vehicle or 25 microgram or 2500 microgram of melatonin, and 32-33 days after surgery. The surgical groups within each injection group were: (1) nonoperated (NO), (2) sham-pinealectomized (S), (3) sham-pinealectomized with black plastic shielding of the pineal region (S + Pl), (4) pinealectomized (PX), and (5) pinealectomized with black plastic shielding of the pineal region (PX + Pl). All injections were made between L11 and L11.75 in a fixed LD14:10 daily photoperiod. Absolute and relative organ weights were significantly depressed by 25 but not 2500 microgram melatonin. This effect of low dose melatonin was blocked by pinealectomy (PX, PX + Pl) in all four organ groups, but was blocked as well by the sham-operation (S, S + Pl) only in the case of the adrenal glands. Effects and organ weights in S animals were not modified in the S + Pl animals. But in vehicle-injected groups the S + Pl animals had significantly lower accessory organ weights in comparison with those of NO and S groups. These results aid in the further definition of the mechanisms of melatonin's physiological actions as a chemical mediator within neuroendocrine timing controls, and show that the mechanisms for melatonin's actions can differ in relation to eventual endpoint target tissue or organ studied.

Pineal atrophy and other neuroendocrine and circumventricular features of the naked mole-rat, Heterocephalus glaber (Rüppell), a fossorial, equatorial rodent

Quantitative aspects of the microanatomy of the pineal gland and other neuroendocrine and circumventricular structures were studied in a small, reproductively suppressed, female Naked Mole-rat from central Kenya, Africa. The atrophic pineal is the smallest in absolute size (0.002135 mm3) of any so far described in a species of rodent, and in size relative to body weight is second only to that of another tropical species. The subcommissural organ and posterior collicular recess are also relatively small and less well differentiated than those in most other examined rodent species. In contrast, the subfornical organ, OVLT and median eminence are large and well vascularized. It is concluded that the pineal in this species follows the previously described trend among rodents of relatively smaller size in species whose centers of distribution are in lower latitudes. Although the pineal is atrophic, the Naked Mole-rat still exhibits 24-hour and seasonally timed patterns of behavior and seasonal reproduction. However, in this species these events are probably cued by moisture, temperature and social factors rather than by photic information.

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

This work describes a special ultrastructural feature, the invagination complex (IC), involving the plasma membrane of nerve endings on adrenomedullary adrenaline cells. Quantitative characteristics of the IC and their changes were studied in 122 male albino (Holtzman strain) rats in 3 surgical groups: normal (non-operated, NO) sham-operated (SO) and pinealectomized (PX), all maintained in a standardized daily photoperiod (light : dark 12 : 12 h). Animals were decapitated 14 days postsurgery and at 8 specific times during the light : dark cycle. Left adrenal glands were removed, dn strain) rats in 3 surgical groups: normal (non-operated, NO) sham-operated (SO) and pinealectomized (PX), all maintained in a standardized daily photoperiod (light : dark 12 : 12 h). Animals were decapitated 14 days postsurgery and at 8 specific times during the light : dark cycle. Left adrenal glands were removed, dn strain) rats in 3 surgical groups: normal (non-operated, NO) sham-operated (SO) and pinealectomized (PX), all maintained in a standardized daily photoperiod (light : dark 12 : 12 h). Animals were decapitated 14 days postsurgery and at 8 specific times during the light : dark cycle. Left adrenal glands were removed, dissected and prepared for electron microscopy. In section profiles the diameter of each IC was usually 0.12-0.40 micrometers, and the depth 0.2-1.0 micrometers. They were frequently seen to be located near the synaptic complex (or the active zone). Coated pits, about 50 nm wide and 60 nm deep, often opened near the bottom of the invaginations of the IC. In NO animals, relative number and depth of the ICs showed daily rhythmic changes with minimal values about 1 h after onset and maximal (acrophase) values 3--5 h later (P less than 0.02 to less than 0.005, depending on index or measure). These changes occurred 3--5 h earlier, but less apparently, in SO animals, and appeared to be more greatly modified and dampened in PX animals. Two-way analysis of variance (ANOVA) and t-tests applied to 11 kinds of indices derived from counts and measurements of the ICs, support the differences between surgical groups, at least in many instances (P less than 0.05 to less than 0.001). It is concluded that the IC is a characteristic and dynamic feature of the nerve terminals and that it may possibly have a role in such phenomena as recycling of synaptic vesicles or related membrane constituents. It is also concluded that significant time-of-day and neuroendocrine effects are demonstrable in these structures, and that the time-of-day effects shown in these chronic studies have importance in the design of acute experiments designed to further test the functional relations and importance of ICs.

Pineal effects on metabolism and glucose homeostasis: evidence for lines of humoral mediation of pineal influences on tumor growth

Results from animal experiments support the hypothesis that pineal gland function can influence some aspects of tissue metabolism and glucose homeostasis. Evidence of pineal effects on particular endocrine and sympatheto-adrenal targets contributes to an understanding of indirect routes by which pineal activity can possibly affect the growth and activity of some kinds of tumors, in part through nutrient and metabolic effects in the tissue environment of the tumor cells.

Experimental and spontaneous pineal tumors: findings relating to endocrine and oncogenic factors and mechanisms

Pineocytomas have been induced in a high percentage of hamsters inoculated intracerebrally within 24 hours after birth with particular strains of a human papovavirus. Studies on biochemical and ultrastructural charactertistics and transformation of such experimentally induced pineal tumors have led to important conclusions and implications: (1) Many of the differentiated pineocytoma cells contained organelles and related structures that are characteristic of hamster pineocytes, and others that are reminiscent of possible phylogenetic precursors, including pineal photoreceptor cells. (2) An inverse relationship was noted between degree of cytological differentiation and level of hydroxyindole-O-methyltransferase (HIOMT) activity in the pineocytomas. (3) It is therefore apparent that even when pineal tumor formation leads to great increase in pinealocyte-like cells, their enzymatic capacity for synthesis fo melatonin, and possibly of other humoral products, may be only 4 to 7% of that of normal pinealocytes if they are of a relatively less differentiated type. A number of important and basic questions are accessible and remain to be investigated via experimental pineocytomas, such as: (1) nature and significance of cytological interactions within the pineal; (2) probable occurrences, correlations and transformations of other pineal biosynthetic and hormonal processes; (3) degree and nature of environmental (photic, circadian and circannual factors) and physiologic controls; and (4) kinds of modifications of pineal-related functions.

Effect of methionine, glycine and serine on serine hydroxymethyltransferase activity in rat glioma and human neuroblastoma cells

Human neuroblastoma SK-N-SH-SY5Y (5Y) and rat glioma (C6) cells were cultured with supplemental methionine, glycine, or serine for three to six days. Serine hydroxmethyltransferase (SHMT: L-serine: tetrahydrofolate 5, 10-hydroxymethyltransferase, EC 2.12.1) was assayed radiometrically in whole cell homogenates, crude supernatant fractions and crude particulate fractions. No significant changes in specific activity or cellular morphology were noted at methionine, glycine, or serine concentrations up to 16 mM. Serine concentrations of 20 and 40 mM led to significantly lower gliomal enzyme specific activities. This activity was unevenly distributed between soluble and particulate fractions, with 190 and 398 nmoles of HCHO formed per mg of protein per hour, respectively. Growth stage and time of incubation were major determinants of enzyme specific activity. C6 cells' specific activity rose slowly with increasing time in culture until cellular confluence. At this time there was a pronounced elevation in specific activity, occurring more rapidly in cells grown in 1.2 mM methionine. Intracellular amino acid analysis of C6 cells demonstrated a significant rise in methionine after four days in media containing 0.2 mM methionine. No appreciable diminution in the intracellular levels of glycine or serine occurred following incubation in excess methionine. It is concluded that SHMT-specific activity in C6 and 5Y cells is not regulated by glycine, serine, or methionine levels and that high concentrations of these amino acids (> 30 mM) are not detrimental to these cells derived from the CNS.

Adrenal and hypothalamic dopamine-beta-hydroxylase activity in the hamster: evidence for species-distinctive day-night and post-pinealectomy differences in activity

Dopamine-beta-hydroxylase (DBH) activities were measured in the adrenal gland and hypothalamus of the golden hamster (Mesocricetus auratus) by means of a sensitive radioenzymatic method. Groups of unoperated control (C), sham pinealectomized (SPX), and pinealectomized (PX) adult males were sacrificed shortly before (09:00 h) and after (11:00 h) the onset of darkness of the daily photoperiod of LD 12:12 (lights on 22:00 h to 10:00 h). In neither adrenal gland nor the hypothalamus were there any day-night changes in the C groups. Pinealectomy led to no significant differences in hypothalamic DBH activity either in light or in dark. However, intracranial surgery resulted in increased DBH activity in the adrenal gland, evident in both light and dark. Although this increase was greatest in the PX groups, intracranial surgery in SPX groups also showed a trend of increase in adrenal DBH, evident even one month after surgery. Such an increase, however, was not found in hypothalamic DBH in the same SPX groups. In both the adrenal gland and the hypothalamus, copper-sensitive endogenous inhibitors of DBH did not show any notable change in concentration, either in relation to the daily light-to-dark change or as a consequence of intracranial surgery. These and related results suggest that important interspecies variations exist in DBH activities in relation to diurnal changes, and also in control or modulation by pineal and other factors.

Effects of pinealectomy and pineal incubation medium and sonicates on insulin release by isolated pancreatic islets in vitro

The present studies were designed to investigate the mechanism of previously-reported nocturnal hyperinsulinemia in the pinealectomized rat. Isolated islets were obtained from anesthetized control, sham-pinealectomized and pinealectomized rats, with 5 rats per surgical groups, during the early dark phase of the daily lightdark cycle. Batches of 3 islets each were incubated in various combinations of 2, 10 or 30 mM glucose with control buffer, medium in which cerebral cortex or pineal glands had previously been incubated for 2 hours, or sonicates of these same tissues. Insulin released into the culture medium was measured by radioimmunoassay. A significant hypersecretion of insulin was demonstrable in the islets from the pinealectomized animals. A stimulatory effect of both pineal medium and sonicates upon insulin release was similarly observed. Neither of these effects displayed an interaction with the concentration of glucose in the islet incubation medium and they, therefore, appear to be mediated by a mechanism which operates independently of stimulation by glucose. These results indicate that the rat pineal gland can exert direct effects upon insulin release from the islets, possibly through a humoral route. Further studies are in progress to characterize the nature and mode of action of the insulinotropic agent present in and released from the pineal gland.

Circadian changes in adrenal dopamine-beta-hydroxylase activity: dependency of change at darkness onset, and the effect of pinealectomy, on animal strain and age

In a previous study we found a daily darkness- and pineal-dependent rise in adrenal dopamine-beta-hydroxylase (DBH) activity in 4-month-old S1 rats. The present investigation shows that aged (12 to 14-month-old) S1 rats do not have such a change in DBH activity. Similarly in the relatively younger (100-day-old) rats of a different (Holtzman) strain such a change was not found. Also pinealectomy did not seem to have any effect on adrenal DBH in either of these two strains of rats, young or old at times just before and after the onset of darkness. In both S1 and Holtzman rats, the concentration of copper-sensitive endogenous inhibitors of DBH remained unaltered following the surgical extirpation of pineal. Photoperiodic change from light to dark also had no significant effect on the inhibitor content in these two strains of rats. It is concluded that there are age and strain dependencies in the behavior of adrenal DBH activity at the daily onset of darkness.

Androgens and brain differentiation. Effects of testosterone on protein synthesis in neonatal rat hypothalamic and cerebral slices

Protein synthetic activity of anterior hypothalamic and neocortical brain slices from androgenized neonatal female rats was studied in vitro in an attempt to clarify the mechanism of action of testosterone on the developing hypothalamus. The short-term effects of testosterone propionate injections of the animals on the protein synthetic activity of the slices were assayed by means of incorporation of 14C-leucine into acid-insoluble protein. Although a high dose (1 mg/animal) of testosterone propionate stimulated increased incorporation in neocortical and anterior hypothalamic slices, a lower dose and other approaches failed to demonstrate a stimulation regionally specific to the anterior hypothalamus. It is concluded that if testosterone has specific stimulatory effects on protein synthesis in the anterior hypothalamus of neonatally androgenized rats, these are not readily demonstrable by methods used with other steroid target tissues.

Daily rhythmic changes in synaptic vesicle contents of nerve endings on adrenomedullary adrenaline cells, and their modification by pinealectomy and sham operations

Nerve endings on adrenaline cells in male rat adrenal medullas were investigated by quantitative electron microscopy, with sampling at 8 times during a standard light: dark (12:12) photoperiod. Number (N) per unit area of 2 vesicle types (small clear vesicle, SCV; large granular vesicle, LGV) and % of LGV per total vesicle N were determined. Normal (non-operated) animals showed a circadian rhythm (p less than 0.005) in mean SCVN and one with nearly opposite phase relations in % LGVN. Doubly sham-operated animals had a similar rhythm in %LGVN but diminished circadian change in SCVN. Pinealectomized animals had a circadian pattern in SCVN, but this differed from that of normals in having a 2nd peak, a delay or phase shift of the primary peak, and an increased amplitude of the rhythmic changes.

Cystathionine synthase in rat brain: regional and time-of-day differences and their metabolic implications

In relation to concern for probable interrelations of cystathionine synthase (CS, EC 4.2.1.21) and methionine, one-carbon, and 5-hydroxytryptamine metabolism, we have investigated tissue and time-of-day differences in CS activity in the laboratory rat under standardized conditions. Liver, kidney, and pancreas had highest CS activities; nine regions of the CNS had mean activities ranging from 4.5% (lumbosacral cord) to 24.5% (hypothalamus) of mean hepatic activity; pituitary and adrenal glands lacked detectable CS activity. Although significantly lower CS activity occurred in liver (9%, P less than 0.050) and kidney (13%, P less than 0.025) during the interval two hours before to two hours after the daily onset of darkness, no significant changes were found in hypothalamus, cerebellum, or medulla oblongata. Regional CNS differences in CS activity appeared to be without correlation in relation to published data on relative contents of 5-hydroxytryptamine, tryptophan 5-hydroxylase (EC 1.14.16.4), 5,10-Methylene reductase (N5-methyltetrahydrofolate-NAD-oxidoreductase, (EC 1.1.1.78), or 5-methyltetrahydrofolate. Therefore, among CNS regions examined, a critical deficiency in ability to metabolize a homocysteine load is considered to be unlikely under normal conditions.

Quantitative morphology and environmental responses of the pineal gland in the collared lemming (Dicrostonyx groenlandicus)

Collared lemmings from Churchill, Manitoba, and their descendants were studied in captivity to define neuroendocrine and related histophsiological characteristics and responses, particularly in relation to photic and temperature conditions. Relatively great pineal size (0.1755 +/- 0.0167 mm3, or 3.08 +/- 0.30 = pineal volume in mm3 X 10(3)/body weight in gm; N = 16) shown in this arctic rodent is consistent with the suggestion that pineal size and significance may tend to be greater in more northern (higher latitude) species. Total number of nucleated cells per pineal averaged 137,000 +/- 10,500. Pinealocytes (105,000 +/- 8,700/pineal) and other cell types were present in relative numbers typical of mammalian pineal glands, and were not numerically correlated with age, sex, or location or circumstances of birth and early postnatal life. Chronic exposure to warmer (21-27 degrees C) in comparison with colder (-9 to -6 degrees C) environments, whatever the illumination, led to greater pinealocyte activity, as shown especially by nucleolar diameter, throughout most of the nine regions of the organ analyzed cytologically (all regions combined: P less than 0.001). Increased pinealocyte activity in chronic darkness was suggested by similar evidence (P less than 0.01), but in comparison with the thermal effects, was less marked and more variable in different regions of the organ. These and other findings of this study indicate that the Dicrostonyx pineal organ is morphologically unique, relatively large in size, and cytologically responsive to environmental conditions.

Modification of plasma dopamine-beta-hydroxylase activity by adrenal and pineal extirpations, and time of day dependency of changes

Plasma level of dopamine-beta-hydroxylase (DBH; EC 1.14.2.1) activity has been considered important both as a diagnostic aid and as an indicator of temporal changes in sympathetic activity. The present study sought to evaluate the possible dependency of some phases of the circadian rhythm in plasma DBH on adrenal and pineal glands. Male Holtzman (albino) rats were shamoperated, adrenalectomized (AX), pinealectomized (PX) or both adrenalectomized and pinealectomized (AXPX) at 32-35 days of age and after acclimation to controlled conditions with a fixed, 12-h, daily photoperiod (LD 12:12). Animals were killed at selected times 15 days postoperatively, and plasma DBH was measured using a sensitive radioenzymatic method. Results from two successive experiments showed that there was significant reduction in plasma DBH in the AXPX animals, but that this was evident only during the middle of the dark phase. PX and AX alone did not bring about any change in the DBH activity at any of the two times tested. These results show that combined endocrine manipulations can alter the circulatory DBH activity level and that such changes can be evaluated only within the definition of a circadian pattern.

Effects of pinealectomy and of sham-pinealectomy on blood glucose levels in the alloxan-diabetic rat

Alloxan-diabetic male rats were used to test effects of pinealectomy (PX) and of sham-pinealectomy (SPX) on blood glucose levels at mid-dark in the daily light-dark (LD 12:12) cycle. Animals received a diabetogenic dose of alloxan 10 days postoperatively. Blood glucose was measured on days -1,1,2,3,4,5,7,10 and 15 after 8-hour fasts. Pinealectomized (PX) and non-operated (C) animals were equivalent in their hyperglycemia following alloxan. SPX animals contrastingly showed significantly less response to alloxan than did animals of the other two groups. This difference of the SPX animals was in terms of lower hyperglycemia, better maintenance of body weight and of survival. It is concluded that intracranial surgery alone (SPX) and without visible brain damage can affect mechanisms of glucose homeostasis, and that at least in some circumstances such a surgical effect is not only different from effects of surgical pinealectomy (PX), but is also probably not pineal-dependent.

Hypothalamic dopamine-beta-hydroxylase activity: fluctuations with time of day and their modifications by intracranial surgery, adrenalectomy, and pinealectomy

Hypothalamic and plasma dopamine-beta-hydroxylase [DBH, EC 1.14.2.1] activites were measured by a coupled radioenzymatic method. Animals representing five experimental groups [intact controls, adrenalectomized, pinealectomized, adrenalectomized pinealectomized, doubly sham-operated] were killed and sampled at 8 times through the 24-hr daily cycle, 15 days postoperation, and at 50-52 days of age. Hypothalamic DBH in intact control animals had statistically significant fluctuations in relation to time of day. These changes were lost or dampened in groups that had had intracranial surgery and were characteristically shifted by adrenalectomy, either alone or with pinealectomy. Plasma DBH fluctuations in the same animals resembled those in hypothalamus in some features (e.g., peak near mid-dark; shift in daily maxima and minima after adrenalectomy) and differed in others [e.g., no effect of intracranial surgery or of sham operation; adrenalectomized pinealectomized animals resembled the solely pinealectomized]. Although temporal patterns in hypothalamic DBH activity thus differed in the experimental animal groups, the daily means of hypothalamic DBH activity were similar.

Quantitative characteristics of the Feyrter cells and neuroepithelial bodies of the fetal rabbit lung in normoxia and short term chronic hypoxia

We report here quantitative data on the Feyrter (single) cells (APUD cells) and neuroepithelial bodies (grouped Feyrter cells), in the lungs of rabbit fetuses at 26, 27.5 and 29 days gestational age, during normoxia and short term chronic hypoxia. The apparent number of these cells declines during this period; we suggest that this might be due to increased hypoxemia. Moreover, the number of cells in the lungs of fetuses from short term chronically hypoxic mothers is lower than in the normoxic animals. These findings are in agreement with our previous studies in short term chronically hypoxic neonatal rabbits, and suggest that the increased hypoxemia in the fetus, caused by the induction of hypoxia in the mother, constitutes a stimulus for secretory activity of the Feyrter cells and neuroepithelial bodies (NEBs). This in turn could be part of the mechanism responsible for maintaining the pulmonary vasoconstriction due to hypoxemia. Our results from fetuses of normoxic does provide base line data on the chronological importance of the Feyrter cells and NEBs.

A radioautographic study of the neuroepithelial bodies of the lungs in fetal and neonatal rabbits

The neuroepithelial bodies (NEB's) of the lung of 29-day-old fetuses and 1-day-old rabbits, under the conditions of this study, neither take up 3H-thymidine nor undergo mitosis. Also the NEB's are not derived at these times from proliferations of other kinds of epithelial cells in the intrapulmonary airways. It is, therefore, suggested that the difference in numbers of NEB's previously observed by us, between the 29-day fetus and the 1-day-old rabbit, is due either to regranulation or acquisition of argyrophilic material by the NEB's or differentiation of other epithelial types. It is concluded that the NEB's are composed of well differentiated cells, which have a greatly reduced capacity to undergo mitosis.