Prevention by pinealectomy of short-photoperiod-induced ultrastructural changes in the hamster harderian gland.код для вставкиСкачать
THE ANATOMICAL RECORD 210:449-452 (1984) Prevention by Pinealectomy of Short-Photoperiod-lnduced Ultrastructural Changes in the Hamster Harderian Gland DENNIS P. DIIORIA AND MATHEW J. NADAKAVUKAREN Biological Sciences Department, Illinois State University, Normal, IL 61 761 ABSTRACT Harderian gland ultrastructure was examined at biweeky intervals for 16 weeks after either pinealectomy or sham-operation of male and female hamsters kept in 1L:23D and 14L:10D photoperiods. Female characteristics such as membrane formations and extensive smooth endoplasmic reticulum appeared in the males kept under short photoperiod conditions. Similarly, male characteristics such as the tubular clusters appeared in the glands of females kept in the short photoperiod. When male and female hamsters were pinealectomized and exposed to the short photoperiod, the glands in each sex retained the characteristics typical of that sex. Atrophy of the testes and uteri was also observed in the sham-operated hamsters maintained under short photoperiods, but not in the pinealectomized animals. The changes observed in the Harderian glands and reproductive organs of hamsters kept in the short photoperiod were not observed in the hamsters maintained in the long photoperiod. The photoperiod-induced ultrastructural changes in the hamster Harderian glands are most likely due to changes in hormonal levels brought about by the regression of reproductive organs and can be prevented by pinealectomy. In a n ultrastructural study of the hamster Harderian gland, Bucana and Nadakavukaren (1972) identified a number of differences between the sexes, the major difference being the presence of tubular clusters in the male gland and the absence of these in the female. Extensive dilated smooth endoplasmic reticulum, Golgi, and concentric lamellar formations are characteristics of the female gland. Previous studies have also indicated that the sexual dimorphism of the hamster Harderian gland is influenced by steroid hormones andor gonadotropins. Castration of the male hamster resulted in the gradual appearance of female characteristics in the Harderian glands (Woolley and Worley, 1954; Hoffman, 1971; Clabough and Norvell, 1973; Payne et al., 1977; Lin and Nadakavukaren, 1979). The development of the female characteristics was prevented when the castrated males were given daily injections of testosterone propionate (Hoffman, 1971; Payne et al., 1977; Lin and Nadakavukaren, 1979) or blinded at the time of castration (Hoffman, 1971; Clabough and Norvell, 1973). The Harderian glands of blinded female hamsters were shown to have lowered levels of porphyrin and cellular char- 0 1984 ALAN R. LISS, INC. acteristics which are normally found in the male gland (Clabough and Norvell, 1974). The conversion of the female Harderian gland to a male type was prevented by pinealectomy a t the time of blinding (Clabough and Norvell, 1974). Sun and Nadakavukaren (1980) reported that the Harderian glands of female hamsters developed male characteristics when the animals were treated daily with testosterone propionate. Recently Nadakavukaren and Lin (1983) demonstrated that the Harderian glands of male hamsters exposed to short photoperiods developed female characteristics and vice versa. Data presented in this paper demonstrate that pinealectomy can prevent the short-photoperiod-induced changes in the Harderian glands of golden hamsters. MATERIALS AND METHODS Sexually mature male and female golden hamsters (Mesocricetus auratus Waterhouse), raised from a stock originally purchased from Con Olson Company, Inc., Madison, WisconReceived August 8, 1983; accepted May 21, 1984. Address reprint requests to M.J. Nadakavukaren, Biological Sciences Department, Illinois State University, Normal IL 61761. 450 D.P. DIIORIA AND M.J. NADAKAVUKAREN sin, USA, were maintained in either a short photoperiod, 1:23 (lights on at 0800 hours, off at 900 hours), or a long photoperiod 14:lO (lights on a t 0800 hours, off at 2200 hours) a t 25°C. The groups of animals under the short photoperiod were either pinealectomized or sham-operated, while two similar groups were maintained under the long photoperiod. Each group consisting of 18 animals was housed separately with food and water given ad libitum. Both pinealectomized and sham-operated male and female hamsters from each photoperiod were killed by decapitation every 2 weeks, beginning a t 4 weeks after exposure to experimental conditions and ending at 16 weeks. The Harderian glands were removed and fixed for electron microscopy according to Bucana and Nadakavukaren (1972). Pinealectomy was performed by a combined method of Hoffman and Reiter (1965) and Kuszak and Rodin (1976) while the hamsters were anesthetized with sodium pentobarbital (0.18 ml i.p./lOO-gm body weight). Sham-operations were performed in the same manner as pinealectomies except that the pineal glands were not removed. RESULTS The Harderian glands of the sham-operated male hamsters maintained in the short photoperiod showed cellular characteristics that are typical of females (Fig. 1). Such structures as membrane formations and dilated smooth endoplasmic reticulum appeared beginning with the 4-week samples. During the same period clusters of membrane-bounded tubules were also found in association with membrane formations. The Harderian glands from the pinealectomized males maintained in the short photoperiod showed no significant changes from those of the normal male hamsters (Fig. 2). The Harderian glands of sham-operated female hamsters maintained in the short photoperiod developed male cellular characteristics (Fig. 3). This primarily included membrane-bounded clusters of tubules, while typical female characteristics such as membrane formations and dilated smooth endoplasmic reticulum gradually decreased. These changes first became apparent after 8 weeks of exposure to the short photoperiod and continued until the end of the experiment. The Harderian glands taken from the pinealectomized females maintained in the short photoperiod showed no significant change from those of normal female hamsters (Fig. 4). Testicular and uterine sizes were greatly reduced after 8 weeks in hamsters that were sham-operated and exposed to the short photoperiod. This atrophy did not occur in animals that were pinealectomized. Animals which were either sham-operated or pinealectomized and then maintained in the long photoperiod did not show any significant change in their Harderian glands during the 16 weeks of the experiment. Testicular and uterine sizes remained normal in all animals that were exposed to the 14L:lOD photoperiod regardless of sham-operation or pinealectomy. DISCUSSION The data presented in this paper demonstrate that pinealectomy can prevent the short photoperiod-induced ultrastructural changes in the Harderian glands of male and female hamsters. Our observations further support the earlier suggestions that the Harderian gland is linked to the retinal-pinealgonadal axis (Wetterberg et al., 1970; Reiter and Klein, 1971; Clabough and Norvell, 1973). It is of interest to note that the changes in the Harderian gland ultrastructure also corresponded to the time when the atrophy of the reproductive organs occurred. Therefore, the ultrastructural changes may have been induced by the altered hormone(s) levels accompanying testicular and uterine atrophy. Earlier studies support this hypothesis in that the levels of testosterone, leutinizing hormone (LH) and follicle-stimulating hormone (F'SH) decreased during short-photoperiod-induced testicular atrophy in male Fig. 1. Acinar cell of sham-operated male hamster after 12 weeks of exposure to 1L:23D photoperiod showing degeneration of tubular clusters (arrow) and formation of membrane whorls typical of females. ~37,000. Fig. 2. Acinar cell of pinealectomized male hamster after 12 weeks of exposure to 1L:23D photoperiod showing many tubular clusters (arrow) typical of normal males. x40,OOO. Fig. 3. Acinar cell of sham-operated female hamster after 16 weeks of exposure to 1L.23D photoperiod showing tubular clusters which are typical of males (arrow). X 37,000. Fig. 4. Acinar cell of pinealectomized frmale hamster after 16 weeks of exposure to 1L:23D photoperiod showing extensive smooth endoplasmic reticulum, Golgi (G), and membrane formations (arrow) typical of normal females. x 37,000. PINEALECTOMY, PHOTOPERIOD AND HARDERIAN GLAND 451 452 D.P. DIIORIA AND M.J. NADAKAVUKAREN hamsters (Berndtson and Desjardins, 1974; Tamarkin et al., 1976; Turck et al., 1976). The hormonal patterns of the female hamsters with reduced uterine size induced by short photoperiod also showed daily afternoon surges of LH and FSH (Seegal and Goldman, 1975; Bridges and Goldman, 1975). In addition, previous studies from our laboratory showed that testosterone has a significant role in regulating the sexual dimorphism of the Harderian gland in the golden hamster (Lin and Nadakavukaren, 1979; Sun and Nadakavukaren, 1980). Recent data further indicate that there are receptor sites for testosterone in the hamster Harderian gland and that testosterone is metabolized by the gland (Hoh and Nadakavukaren, unpublished results). Therefore, there is strong indirect evidence to suggest that testosterone levels are more likely responsible for the observed ultrastructural changes than the levels of LH and FSH. ACKNOWLEDGMENTS We thank Dr. John L. Frehn for the internal review of this paper. LITERATURE CITED Berndtson, W.E., and C. Desjardins (1974) Circulating LH and FSH levels and testicular function in hamsters during light deprivation and subsequent photoperiod stimulation. Endocrinology, 95: 195-205. Bridges, R.S., and B.D. Goldman (1975)Diurnal rhythms in gonadotrophins and progesterone in lactating and photoperiod induced acyclic hamsters. Biol. Reprod., 13t617-622. Bucana, C.D., and M.J. Nadakavukaren (1972) Fine structure of the Hamster Harderian Gland. Z. Zellforsh., 129t178-187. Clabough, J.W., and J.E. 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