Showing papers on "Pinealectomy published in 1977"

Circadian organization in lizards: the role of the pineal organ.

Abstract: After pinealectomy, the iguanid lizard Sceloporus olivaceus exhibits a "splitting" of the circadian activity rhythm into two components, marked changes in the period of the rhythm, or arrhythmicity. These effects are consistent with either of two hypotheses: (i) The pineal organ is a coupling device between circadian oscillators in a multioscillator system, or (ii) the pineal organ is itself a master oscillator, which entrains other circadian oscillators and imposes its frequency upon them.

A new technique of pinealectomy for adult rats

Abstract: A new technique of pinealectomy for rats is described which brings the pineal into view of the experimenter facilitating its removal and also allows for completely parallel sham operations.

Pinealectomy and photoperiod influence testicular development in the Djungarian hamster.

Abstract: One of the most effective economical and environmentally acceptable forms of agricultural pest control consists of built-in resistance or immunity of the host plant toward potential predators. By establishing the nature of host-plant resistance, one may hope to facilitate the selection of crops possessing immunity of this sort. Sunflower moth (Homoeosoma electellum, H.) is a major pest of sunflower (Helianthus annus, L.) an increasingly important crop in the United States. Sazyperov [1] and Kiewnick [2] have suggested that the resistance of sunflower seed to damage by European sunflower moth (H. nebulella, H.) is associated with the presence of phytomelanin or \"armored layer\" in the seed coat which becomes recognizable after chromic-acid treatment [2, 3]. The term \"armored layer\" implies physical resistance to penetration of the seed coat by the larvae. Correlation between the presence of a phytomelanin layer and reduced larval damage was also reported in the United States [3]. We find evidence that host-plant resistance to the sunflower moth (H. electellum) is caused by chemical factors. We have observed that sunflower-moth larvae in their first and second instars feed mostly on florets of the host plant. As the larvae grow, they proceed to attack the immature seeds. On occasions some larvae do penetrate the seeds of resistant varieties, although the damage is less severe for them than for susceptible varieties. The penetrabilities of immature sunflower seeds from both resistant and susceptible varieties, measured by a tensile tester, are not significantly different. On the other hand the young larvae died within a week after being fed on a synthetic diet [4, 5] containing 5% ofhexane extract from florets of a resistant variety (H 2135) while normal development occurred with larvae fed on a diet containing 20% of the extraction residue. Liquid chromatography (silica gel) of this extract yielded two fractions which inhibited larval growth. Crystallization gave two isomeric diterpenoid acids (Fig. 1) which were shown to be the previously described trachyloban-19-oic (I) and ( ) kaur16-en19-oic (II) acids by comparison with published data [5, 6]. Quantitative GLC analysis (1.8 m OV-17 at 200~ of I and II as methyl esters indicated that dried sunfower florets maycontain in some cases over 5 % in combined amount of these compounds. This result depends upon the maturity of the floret as well as the particular variety of sunflower, and tests are underway to correlate levels of I and II with field resistance to moth damage.

Effects of pinealectomy on pituitary gonadotrophs, pituitary gonadotropin potency and hypothalamic gonadotropin releasing activity in Notemigonus crysoleucas

Abstract: The effects of pinealectomy on pituitary gonadotrophs, pituitary gonadotropin potency and hypothalamic gonadotropin releasing activity were examined in the cyprinid teleost, Notemigonus crysoleucas, exposed to various photoperiod-temperature regimes. In fish exposed to a long photoperiod-warm temperature regime, pinealectomy resulted in a decrease in gonadal activity, in hypothalamic gonadotropin releasing activity and an increase in pituitary gonadotropin potency. Fewer gonadotrophs were present in the pituitary of sham operated fish than in the pituitary of pinealectomized fish. Ovarian development was more rapid in sham operated than in pinealectomized fish exposed to a long photoperiod–low temperature regime. Pituitary gonadotropin activity was also greater in shams than in pinealectomized fish. A short photoperiod-warm temperature regime retarded ovarian development in N. crysoleucas. Pinealectomy reversed this trend. Gonadotrophs made up a greater area of the pituitary in pinealectomized fish than in shams under these conditions. Gonadotropin potency of the pituitary and hypothalamic gonadotropin releasing activity were also greater in pinealectomized fish than in shams. The area of the pituitary occupied by gonadotrophs was greater in pinealectomized than in sham operated animals maintained on a short photoperiod-low temperature regime. Pituitary gonadotropin activity was also greater in pinealectomized fish as compared to shams. Pituitary gonadotropin potency varies diurnally in animals maintained on both short and long photoperiods; the rhythm of variation differs depending on photoperiod. Pinealectomy alters the diurnal rhythm of pituitary gonadotropin potency in animals exposed to both long and short photoperiods. It is concluded that pinealectomy has a pronounced effect on reproductive activity in N. crysoleucas. The effects of pinealectomy on reproduction vary with photoperiod, but are mediated via the hypothalamus and pituitary. In fish exposed to long daylengths the pineal favours reproductive activity, but the epiphysis retards reproductive processes in animals maintained on short photoperiods.

Effects of blinding, pinealectomy and superior cervical ganglionectomy on free thyroxine index of male golden hamsters.

Abstract: Blinding young male golden hamsters led to a depression of the plasma free thyroxine index after an 8 week period. Removal of either the pineal gland or the superior cervical ganglia of blind hamsters reversed the effects of blinding on free thyroxine index. No significant effects were observed 2 weeks after treatment. Previously reported effects of blinking, and removal of the pineal gland or the superior cervical ganglia on testicular weight were confirmed. A similar mechanism of pineal inhibition of thyroid function and gonadal function is suggested.

Endocrine effects of the pineal gland and neutralization of circulating melatonin and N-acetylserotonin.

Abstract: Adrenocortical function was studied in rats after shampinealectomy, pinealectomy, or immunization against melatonin and N-acetylserotonin (NAS). Pineals were stimulated to increase melatonin synthesis by blinding or exposure to 23 h of darkness daily. Blinding elevated morning corticosterone levels without altering the corticosterone response to novelty stimulation. Among blinded animals, pinealectomy partially reversed and immunization completely reversed the elevations in morning steroid levels. Exposure to short daily photoperiods flattened the diurnal corticosterone rhythm. Pinealectomy did not affect morning corticosterone levels but reduced evening corticosterone levels. More importantly, immunization resulted in reduced corticosterone levels throughout the diurnal cycle. These findings suggest that melatonin and (or) NAS may be involved in the regulation of resting diurnal adrenocortical function.

Effects of neutralization of circulating melatonin and N-acetylserotonin on plasma prolactin levels.

Abstract: The effect of pinealectomy or immunization against melatonin (Mel) and N-acetylserotonin (NAS) on plasma prolactin (Prl) levels was studied in rats following pineal stimulation induced by blinding or exposure to short photoperiods (1 h light and 23 h darkness daily). Blinding alone or together with pinealectomy or immunization did not alter resting Prl levels or the response to novelty stimulation. Exposure to short photoperiods flattened the diurnal Rrl rhythm seen in control rats kept in 12 h of light and 12 h of darkness daily. Pinealectomy slightly lowered Prl levels but did not affect the diurnal rhythm. Immunization caused a significant reduction in Prl levels, although the diurnal Prl rhythm persisted. These data suggest that Mel and/or NAS may be involved in the maintenance of basal Prl levels.

Gonadal Function in Underfed Rats: I. Effect of Pineal Gland and Constant Light on Maturation and Fecundity

Abstract: Rats were underfed from birth to determine the effects of chronic food deprivation on gonadal function. Pups were allowed to nurse for 12 h out of 24 untilthey were weaned. Thereafter,they received 50 percent of the daily amount of food consumed by controls. Besides being underfed, animals were also pinealectomized and/or maintained in constant light. Although delayed, vaginal opening occurred in all underfed groups. Two or three extended estrous cyclesoccurred aftervaginalopening, then the animals became anestrus; however, cycling was restored when they were placed in constant light or with a male. Despite irregularestrous cycles in underfed females, they copulated, became pregnant and gave birth to littersof normal size and composition. Similarly, underfed males impregnated fed females. Continuous illumination or pinealectomy stimulated compensatory hypertrophy in the remaining ovary afterhemiovariectomy both in ratsunderfed from birth and in starved adults which had achieved normal growth prior to underfeeding; however, the lattertreatment was not as effectiveas the former. It did, however, increase ovarian weight prior to surgery. The adverse effects of underfeeding on reproductive function may be due to physiologic alteration resulting in a new pattern of control, rather than simply a reduced rate or lack of function due to less available energy, since the gonads may be stimulated to renewed activity by environmental or surgical manipulations.

Gonadal Function in Underfed Rats: II. Effect of Estrogen on Plasma Gonadotropins After Pinealectomy or Constant Light Exposure

Abstract: The effect of underfeeding on the control of plasma levels of FSH and LH was investigated in female rats after long term food deprivation. Concentrations of these hormones were measured in ovariectomized animals by radioimmunoassay, before and after injection of a single dose of estradiol. Similar measurements were made in animals which had been previously pinealectomized or exposed to continuous illumination, since such treatment partially restores activity to the quiescent reproductive tissues of rats which are maintained on a low caloric diet. While levels of plasma FSH were comparable in fed and underfed ovariectomized animals. LH was significantly lowered in the latter group. It is suggested, therefore, that the major factor contributing to reproductive dormancy in the starved animal is reduced plasma LII. This reduction was not apparently due totally to enhanced feedback sensitivity by estrogen, since it was observed in ovariectomized rats, but occurred in part through some mechanism which is sensitive to constant light exposure or pineal gland removal. Such treatment resulted in elevations of blood levels of LH, but had little effect on plasma FSH levels in underfed rats. It is therefore suggested, that energy conservation during periods of food shortage is facilitated by the establishment of control mechanisms leading to gonadal quiescence by inhibition of LH secretion. This mechanism is in part dependent upon the pineal gland for optimal function and it is potentiated by a relatively short

Persistence of circadian activity rhythms in pinealectomized European Starlings (Sturnus vulgaris)

Abstract: Surgical removal of pineal glands from adult male European Starlings (Sturnus vulgaris) does not alter circadian perch-hopping activity rhythms characteristic of this species maintained in constant darkness. The average free-running period of the activity rhythms of ten pinealectomized birds was 24.61 hours, compared to the previously reported period of 24.48 hours for intact starlings under identical conditions. These results conflict with those reported for three other passerine species in which pinealectomy abolishes circadian activity patterns. In addition, the data do not support the recently proposed model of Menaker and Zimmerman that suggests that the pineal gland is the site of the self-sustained oscillator in the circadian timing system of birds.

The role of the pineal gland in reproduction.

Abstract: The present paper presents a number of results concerning the role of the pineal gland in reproduction. It has been demonstrated that the pineal polypeptides and a substance isolated by the author from children's urine and proved to have pineal extract-like actions, administered to laboratory animals induced the following effects: 1) inhibition of the exogenous HCG stimulating effect on mouse uterus, 2) decrease in excretion of the 17-KS of both testicular and adrenal origin, 3) decrease in the testis oxygen consumption in vitro, and 4) marked decrease of the serum and testicular testosterone. Melatonin, a pineal indole, studied in parallel did not alter the above biochemical indices. Pinealectomy produced in all the cases completely opposite effects. The effects obtained with the pineal polypeptides, the urinary antisteroid substance, and melatonin are discussed.

Gonadotrophin concentrations during growth and maturation in domestic turkeys

Abstract: 1. Circulating immuno‐reactive‐luteinising hormone (LH) and follicle stimulating hormone (FSH) were measured between hatching and either 17 or 30 weeks of age in turkeys. 2. In one experiment both sexes were reared together. The pattern of changes in gonadotrophin concentration with age consisted of high LH concentrations at 3 to 8 and 16 to 19 weeks old and FSH peaks between weeks 3 and 10 and at weeks 18 and 19. 3. In two separate experiments male and female birds were reared separately for 17 weeks. In these turkeys the LH concentration was high for 3 weeks following hatching and also after 10 weeks, while FSH was elevated at weeks 10 and 15 in females and at weeks 7 and 13 in males. 4. There were lower plasma LH concentrations in turkeys which had received testosterone implants while the FSH concentration was elevated. 5. Pinealectomy in female turkeys led to increased FSH concentrations at 2 weeks but depressed FSH concentrations thereafter.

The role of the pineal gland in the regulation of LH-release in rats with different types of the anovulatory syndrome.

Abstract: The effect of different doses of testosterone propionate was investigated in provoking the development of the constant estrous anovulatory (CEA) syndrome in the rat. A direct relationship was observed between the dose of neonatally administered androgen (NA) and the percentage occurrence of this syndrome. Pinealectomy and superior cervical sympathetic ganglionectomy elicited the development of marked thecal luteinization in the NA-CEA rat, but the formation of corpora lutea was limited after these operations. The efficacy of pinealectomy and ganglionectomy in provoking luteinization was inversely related to the dose of testosterone used for neonatal androgenization. The LH-RH sensitivity of the adenohypophysis to release LH was decreased in the NA animals, as well as in the light-induced CEA syndrome (LCE), whereas it was increased in those CEA rats in which this syndrome was provoked by frontal hypothalamic deafferentation (FHD). Pinealectomy and ganglionectomy were able to elicit ovulation and luteinization in the FHD animals, but were ineffective in the LCE and high dose NA rats. The results are discussed in relation to those reported by others, in an attempt to explain the multitude of dissociated effects.

Der Einfluss der Epiphyse auf die Lokomotionsaktivität bei Ratten

Abstract: After pinealectomy adult hypoactive rats show an increased exploratory behavior, whereas adult hyperactive rats show no significant behavioral change. These data are discussed in relation to brain serotonin content.

Pineal-induced alterations in reproductive function and pituitary prolactin in the female rat: the effects of bilateral superior cervical ganglionectomy and nervi conarii transection.

Abstract: The reproductive organs of female rats subjected to blinding and and anosmia were hypotrophic while pituitary prolactin stores were markedly depressed in these animals. All of the effects of dual sensory deprivation were reversed by either superior cervical ganglionectomy or nervi conarii transection. It was concluded that both of these surgical procedures were as effective as pinealectomy in reversing the pineal-induced alterations in the reproductive physiology of the blind-anosmic female rat.

A surgical operating apparatus for fish and its use in the pinealectomy of salmonids

Abstract: A surgical operating apparatus for fish that is effective for cranial surgery is described. The fishes are secured with clamp-arms which extend against the pectoral and pelvic girdles. The head is held by a plexiglass mouthpiece, designed specifically for the fish species under investigation. The mouthpiece is also responsible for gill irrigation. The use of the apparatus for the surgical pinealectomy of salmonids is described.

Effects of precocious pinealectomy and hemicastration on pituitary and plasma LH levels in immature male rats.

Abstract: In the immature male rat (7 to 28 days of age) precocious hemicastration provokes a marked compensatory testicular hypertrophy accompanied by a significant increase in pituitary LH content, and a non-significant increase in plasma LH level. In pinealectomized and sham-pinealectomized animals, hemicastration had the same effect with some exceptions at certain ages. Pinealectomy alone causes less evident changes in pituitary LH content than hemicastration. Only a transient effect was found, which was more evident in the hemicastrated rats. Plasma LH was only increased in the pinealectomized hemicastrated rats at days 16 and 18. It is concluded that pinealectomy in immature male rats seems to have only a transient stimulatory effect on pituitary and plasma LH levels, which is more striking in hemicastrated rats. So, hemicastration seems to sensitize the animals to the effect of pinealectomy.

Blinding and pinealectomy in male hamsters: Effects of pineal indoles and P-chlorophenylalanine on testes, seminal vesicles, pituitary and adrenal glands.

Abstract: No antigonadotrophic (AGT) activity was found after injecting 5 methoxytryptophol (5 MTPH) or both serotonin and melatonin simultaneously in normal male hamsters or hamsters subjected to blinding, pinealectomy, or both surgical procedures. Treatment with these indoles did not induce changes in weights of testes, seminal vesicles, pituitary or adrenal glands. Reproductive organs in hamsters blinded by enucleation atrophied in spite of daily consumption of the vasodilator, Apresoline. Feeding of p-Chlorophenylalanine (PCPA) revealed this antagonist to be mildly toxic. PCPA seemed to interfere in the hypophyseal-adrenal axis: these hamsters lowt the most weight, pituitary glands were enlarged and some hyperactivity occurred in the hamsters.

Surgical approach for pinealectomy in the calf.

Abstract: Pinealectomy was performed on 7 calves, and a sham operation was performed on 3 calves. Two pinealectomized calves died immediately. The 5 remaining pinealectomized and 3 sham-operated control calves are presently involved in experimental studies. The surgical technique for exposure of the pineal gland was a rectangular (rostrotentorial) craniectomy between the median line and the horn bud. Removal of portions of the frontal and parietal bones, measuring 6 cm by 4 cm, provided adequate exposure. Positioning the head was important in order to gain the best access to the pineal gland. Water deprivation, hypertonic solution, elevation of the head, and hyperventilation prevented brain edema during the operation. The dura mater was sutured and glucocorticoids were administered to prevent postsurgical brain edema. Bone graft or plate was not placed over the craniectomy site. The soft tissue flap was repositioned over the dura mater and sutured in place--the periosteum and muscle comprising 1 layer and the skin a 2nd layer. Postsurgical complications were observed only in the 2 calves which died and were the result of hemorrhage and leukomalacia.