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

Unique effects of sham-pinealectomy [intracranial surgery (IS)] which include reduced functional activity of the adrenal gland and suppressed circadian rhythms of the adrenal medulla, and which are reversed by pinealectomy, have been reported in rodents. To clarify the mechanisms, we investigated whether or what changes occur in pineal functional activity after IS. Sixty-six male rats of normal and IS groups were used at 50 days of age. The pineal gland was first examined by quantitative electron microscopy. The Sudan III-stained lipid droplet content of the pinealocytes and plasma melatonin level were then investigated using the same animals. In IS rats, the lipid droplet content of the pinealocytes decreased in both the dark and light phases 14 days after surgery. Mean volumetric ratio of nucleus, nucleolus, and mitochondria tended to increase in IS rats. The mean plasma concentration of melatonin showed apparent day-night changes, but no significant changes because of IS, 36 h and 14 days after surgery. But in the dark phase 14 days after surgery, plasma melatonin levels showed increased dispersion of values (P < 0.04). Thus, after IS the lipid content of pinealocytes showed changes not closely related to those of plasma melatonin level. From these and other results it is speculated that IS effects are dissimilar to usual stress responses, that day-night rhythms of functional activities of the pineal and adrenal medulla are differently controlled, and that pineal gland-dependent IS effects are most probably induced by changed sensitivity/states of target mechanisms to the pineal hormone melatonin.

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.

Surgical anatomy of the nuchal muscles in the posterior cervicothoracic junction: significance of the preservation of the C7 spinous process in cervical laminoplasty.

STUDY DESIGN: An anatomic study investigated the attachment of the nuchal muscles to the spinous process. OBJECTIVE: To investigate the anatomic details of the attachment of the nuchal muscles to the spinous process, and which muscles are spared, and to what extent, when the C7 spinous process is preserved in the cervical laminoplasty. SUMMARY OF BACKGROUND DATA: In previous studies, it was reported that the incidence of postoperative axial pain was lower in C3-C6 laminoplasty than in C3-C7 laminoplasty, emphasizing the effectiveness of the former procedure where discission of the nuchal muscles that are attached to the C7 spinous process is avoided. However, there have been no detailed anatomic studies of the attachment of the nuchal muscles to the spinous process at the cervicothoracic junction. METHODS: The anatomy of the speculum rhomboideum of the trapezius, rhomboideus minor, rhomboideus major, serratus posterior superior, splenius capitis, and splenius cervicis to the spinous processes of the cervicothoracic junction were studied using 50 cadavers. RESULTS: The possibility of total discission of the speculum rhomboideum of the trapezius was 0% with C3-C6 laminoplasty and 18% with C3-C7 laminoplasty. More than 50% preservation of the speculum rhomboideum of the trapezius is possible in 72% in C3-C6 laminoplasty and 16% in C3-C7 laminoplasty. In C3-C7 laminoplasty, the possibility of partial preservation of the rhomboideus minor, serratus posterior superior, and splenius capitis at the spinous process was 0%, 66%, and 29%, respectively. The rhomboideus major in 16% and the splenius cervicis in 56% could be completely preserved without partial discission of the muscle attachment. On the other hand, in C3-C6 laminoplasty, the muscles that were spared without complete discission of the muscular attachment at the spinous process were the rhomboideus minor in 35%, the serratus posterior superior in 100% and the splenius capitis in 67%. The rhomboideus major in 76% and the splenius cervicis in 80% were completely spared without partial discission of the muscular attachment. CONCLUSION: The current study confirmed that C3-C6 laminoplasty in which the C7 spinous process is preserved reduces invasion of the nuchal muscles.

A qualitative and quantitative electron microscopic study of differences in adrenomedullary adrenaline cells between golden hamsters and rats, with special reference to the Golgi apparatus.

Ultrastructural features of adrenomedullary adrenaline (A) cells in golden hamsters and rats were investigated qualitatively and quantitatively with special reference to the Golgi apparatus. The A cells displayed a characteristic follicular arrangement, with each cell showing structural polarity in hamsters, but not apparently in rats. In hamsters, the Golgi apparatus of A cells was larger (t-test: P<0.001) and more frequently showed large and complexly organized structures (chi(2)-test: P<0.005) compared with that of rats. Quantitative analysis of the Golgi apparatus revealed differences in the size and numerical density of Golgi vesicles in relation to the animal species and region. Two-way analysis of variance (ANOVA) confirmed species difference in the size of coated vesicles (P<0.005) and interaction between species and region concerning the size of smooth-clear vesicles (P<0.01) and numerical density of granular vesicles (P<0.05). One-way ANOVA revealed regional differences in the size and numerical density of smooth-clear vesicles in rats and hamsters (P<0.01 approximately 0.001), and in the numerical density of coated vesicles in hamsters (P<0.05). Data were further analyzed by Tukey-Kramer's method. These and other reported results suggest that, in hamster A cells, the Golgi apparatus has different structural, molecular, and functional mechanisms which are at least partly related to the distinct cellular polarity and higher concentration of peptide hormones in secretory vesicles, and that in rat A cells, in contrast, loading secretory vesicles with A during the post-Golgi stage is predominant. In conclusion, the Golgi apparatus in hamster A cells shows markedly different ultrastructural features compared with that in rat A cells.

Physiological pineal effects on female reproductive function of laboratory rats: prenatal development of pups, litter size and estrous cycle in middle age.

The present study investigates whether and how the pineal or its hormone melatonin influences female reproductive functions, namely the litter size, prenatal development of offsprings, and estrous cyclicity, especially its age-related cessation in a non-seasonal breeder, the laboratory rat. Wistar rats were maintained under a 24 h light-dark (12Lratio12D) cycle. Female rats were divided into 3 groups: non-operated (NO), sham-operated (SX), and pinealectomized (PX). Surgeries were performed in 35-40 day-old females. Starting at an age between 70 days and 7 months, female rats of all 3 groups were repeatedly mated with intact males. PX mothers more frequently delivered pups with malformations (e.g., taillessness, hydronephrosis, 7 out of 1263 pups) than control rats (0/1323; p<0.007). In the first delivery at 3 months of age, but not at later ages, PX mothers delivered more pups of lower body weight than control animals (p<0.001). Examination of vaginal smears showed that almost all female rats of the NO, SX, and PX groups had 4-day estrous cyclicity when they were young-between 60 days and 5 months of age. At an age of 17 to 18 months, most female rats of the NO and SX groups showed irregular, continuously diestrous or pseudopregnancy-like patterns, and 4-day estrous cyclicity was found in only 10% of the NO or SX animals. In contrast, about 50% of the PX rats showed 4-day estrous cyclicity at this older age (p< 0.001). Melatonin, when added to drinking water (0.4 mg/L) for 16 days during the dark phase increased the frequency of diestrous phase, except in continuously diestrous rats and very few others. This melatonin effect was strong in PX rats but relatively weak in SX rats. In conclusion, the pineal hormone appears to influence various reproductive functions and developmental processes, especially pregnancy and the timing of reproductive aging in rats. The effects of pinealectomy are more prominent at an age of 60 to 80 days (i.e., shortly after puberty) and at the beginning of the cessation of cycles in middle-aged females.

Inhibitory effects of adrenomedullary hormone on the induction and growth of fibrosarcoma by methylcholanthrene.

OBJECTIVE: Effects of adrenomedullary hormone(s) on the induction and growth of fibrosarcoma by methylcholanthrene (MC) were examined. METHODS: At 28 days of age, male Wistar rats were divided into four groups: 1) control, 2) bilateral adrenomedullectomy (Bil. AMX), 3) right AMX + left adrenomedullary autotransplantation (AMX + AMT), 4) Bil. AMX + epinephrine injection (Bil. AMX + E) groups. 14 days after surgery, MC crystals were inserted underneath the dorsal skin, and in the Bil. AMX + E group, epinephrine was injected subcutaneously, twice every week. RESULTS: The incidence of tumor at 90 days after the MC injection was 8 per 35 cases (22.9%) in the control group, 12 per 36 cases (33.3%) in the AMX + AMT group, 8 per 28 cases (28.6%) in the Bil. AMX + E group, and each value was lower compared with that of the Bil. AMX group, 24 per 34 cases (70.6 %), (P<0.001, P<0.002, P<0.005). Such differences among groups were not seen at 165 days after the injection of MC. DISCUSSION: The mechanisms of effects of AMX, AMT and/or epinephrine on the tumor incidence have been discussed with reference to tumor promotion, vascular neoplasia, etc. Since norepinephrine remaining in the blood of AMX rats was ineffective, at least it is likely that this inhibitory effect of epinephrine is mediated via the beta2-receptor. CONCLUSION: The results suggest that adrenomedullary hormone, probably epinephrine, has inhibitory effects on the induction and growth of fibrosarcoma by MC, particularly in the early stage.

Increased incidence of spontaneous malformations in pups and increased litter size from pinealectomized dams.

The aim of the present study was to clarify whether maternal pinealectomy increases: (i) the incidence of spontaneous malformations in offspring; and (ii) litter size. More than 30 female rats in each of the control groups (normal and sham-pinealectomized) and the pinealectomized group were mated repeatedly with normal male rats and pups were autopsied mostly before weaning. No malformations were seen in offspring from the normal and sham-pinealectomized groups (n = 350 and n = 736, respectively). In contrast, in offspring from pinealectomized mothers (n = 1123), spontaneous malformations were found in five (taillessness in three and unilateral hydronephrosis or large renal cyst in the other two) or maybe six (unilateral renal hypoplasia in another) pups. This increased incidence of malformations in the latter group was statistically significant (P < 0.034 or 0.017 (Fisher's exact test), respectively). The frequency of still-born cases was not higher in pups born from pinealectomized mothers. The mean litter size was larger in the pinealectomized group compared with the control groups (P < 0.005-0.001, Student's t-test) at the first delivery (at approximately 100 days of age), but was not different at later deliveries at older ages. Our results suggest that the maternal pineal hormone suppresses: (i) the incidence of spontaneous malformations in offspring until mothers reach an old age; and (ii) litter size during the reproductively maturational phase of life.