Showing papers on "Pinealectomy published in 1971"

Pineal Function in Sparrows: Circadian Rhythms and Body Temperature

Abstract: Deep body temperature of the house sparrow, Passer domesticus, was monitored continuously by radio telemetry. Pinealectomy abolished the normal circadian rhythm of body temperature in constant darkness, and significantly altered the amplitude of body temperature rhythms entrained to light cycles. The body temperature minima of pinealectomized birds never fell as low as those of unoperated birds regardless of the light conditions; the temperature maxima of both normal and pinealectomized birds were higher in light than in darkness. In sparrows the pineal organ is essential to the normal function of the biological clock controlling both activity and body temperature rhythms and may be directly involved in thermoregulation.

Relative efficacy of pinealectomy, hypothalamic and amygdaloid lesions in advancing puberty.

Abstract: To evaluate the comparative accelerating effects on puberty individually reported to be produced by pinealectomy (P), anterior-basal hypothalamic lesions (ABH) and bilateral amygdaloid lesions (AMYG), these operations were performed on 4-day-old rats according to a design based on random numbers, which also included corresponding sham-operated animals. All rats were reared in diurnal lighting and the females sacrificed on the day of vaginal opening. Both the P and ABH rats matured at essentially the same time (32–33 days), and earlier than their respective shams, Psh and ABHsh; the latter 2 and the amygdaloid shams (AMYGsh) did not reveal any essential difference in age at maturation (41–42 days). However, the AMYG rats matured even later (61 days) than the AMYGsh rats. These results of amygdaloid lesioning are contrasted with those of another experiment in which amygdaloid lesioning of 18- to 20-day-old female rats accelerated puberty. The possible reasons for these divergent findings are discussed and i...

Effects of Pinealectomy on the Testicular Function of the Adult Male Duck

Abstract: The effects of pinealectomy on the weight, the in vitro biosynthesis of steroids and the testosterone content of the duck testis (Anas platyrhinchos) were studied during an annual cycle. In control animals the testicular weight increased up to 12 times from the nonbreeding to the breeding season. Progesterone-4-14C was metabolized to 17α-hydroxypregn-4-en- 3,20-dione, androstenedione, testosterone, 5αpregnane- 3,20-dione, 5α-androstane-3,17-dione, 20α-hydroxypregn-4-en-3-one and 17α,2Oα-dihydroxypregn- 4-en-3-one. Pregnenolone-4-14C was converted to the same products plus progesterone, 3β, 17α-dihydroxypregn-5-en-20-one and dehydroepiandrosterone. All the enzymatic activities were localized in the microsomal fractions. The in vitro percent conversion of both substrates was higher during the non-breeding season, with the exception of the 20α-reduced metabolites. There was a close correlation between the evolution of the testicular weight and the testosterone content of the testis, which varied from 87 ± 7 ...

Central and peripheral neural pathways necessary for pineal function in the adult female rat.

Abstract: Reproductive involution produced by surgical removal of the olfactory bulbs and of the eyes from adult female rats was prevented by pinealectomy, superior cervical ganglionectomy or by bilateral trans

Pineal Regulation of Growth Hormone Synthesis and Release in Blinded and Blinded-Anosmic Male Rats

Abstract: Removal of eyes from young male rats led to slight retardation in body weight gain, tibial length, and tail length compared with respective parameters measured in normal rats. Young rats lacking eyes and pineal glands presented body weights, tibial lengths, and tail lengths that approached normal. Pituitary levels of radio-immunoassayable growth hormone (GH) were significantly lower in blinded rats with intact pineal glands compared with levels in normal or blinded-pinealectomized rats. Plasma levels of GH tended to be lower in blinded and blinded- pinealectomized rats relative to normal levels; however, due to the wide range of GH levels in all groups, no statistically significant differences were observed. Blindness and anosmia in young male rats severely retarded body weight gain, tibial length, and tail length relative to respective parameters of normal, blinded, blinded-pinealectomized, and blinded-anosmic-pinealectomized rats. Blinded-anosmic-pineal-ectomized rats grew subnormally, with body weights equal to those of blinded rats. Plasma GH concentrations were low in blinded-anosmic rats, but due to the overlapping values, statistical significance was not attained. In general, the size of reproductive organs correlated well with inhibition of body growth, being moderately smaller in blinded rats and markedly so in blinded-anosmic rats. These differences in the size of the reproductive organs were not observed if pinealectomy was performed simultaneously with blinding and olfactory bulb removal. It is concluded that, in young male rats that are deprived of light by blinding, there is a dramatic inhibition of GH production and release by the pituitary gland. This response, like the response of the reproductive organs, is enhanced when rats are deprived of both smell and light. These phenomena only occur in the presence of the pineal gland. Therefore, the pineal gland plays an important role in these processes. It is further concluded that anosmia or perhaps non-specific surgical stress may alter GH synthesis and/or release from the pituitary gland.

Pineal Hydroxyindole-O-Methyltransferase and Gonadal Responses to Blinding or Continuous Darkness Blocked by Pineal Denervation in the Male Hamster

Abstract: Denervation of the pineal by cervical sympathectomy is equivalent to pinealectomy in blocking the testicular atrophy caused by blinding or exposure of male hamsters to constant darkness. Ganglionectom

Influence of the Pineal Gland on the Neurosecretory Activity of the Supraoptic Hypothalamic Nucleus in the Male Rat

Abstract: In male rats pinealectomized at 4–9 weeks of age and decapitated after survival periods of 2–6 weeks, the neurosecretory activity of the hypothalamic magnocellular supraoptic nucleus (SON) was studied

Effects of an aldosterone antagonist, spironolactone, on pinealectomized rats.

Abstract: The possible role of aldosterone in pinealectomy induced hypertension was studied by using daily spironolactone administration (10 mg/kg orally) from the second postoperative day. induced blood pressure elevation was Pinealectomy partly inhibited and the reduction of serum potassium concentration antagonized by spironolactone. The urine volume was increased but the excretion of sodium and potassium decreased in pinealectomized animals. These changes, too, were prevented by spironolactone administration. In spironolactone treated pinealectomized rats the sodium concentration was slightly increased in both the heart and the arterial wall. The ability of spironolactone to antagonize the pinealectomy induced hypertension and the changes in the electrolyte concentrations in plasma and urine supports our earlier suggestion of an increased aldosterone secretion in this type of hypertension in rats.

Absence of Gonadotropin-Inhibiting Substance in the Urine of Pinealectomized Rats

Abstract: A study was made to observe the influence of pinealectomy on the excretion of a gonadotropin inhibitor in the urine of male rats. Ovulation induced with PMS and HCG was not inhibited in mice which received a heated extract prepared from the urine of pinealectomized rats, whereas ovulation was inhibited in mice given a heated extract from the urine of intact and of sham-operated rats. Ovulation was also partially inhibited in mice receiving a heated extract from the urine of hypophysectomized rats. These observations suggest that the pineal may be the secreting organ of a gonadotropin inhibitor and that the pituitary may be involved in the secretion of the inhibitor in rats. (Endocrinology 88: 816, 1971)

Lack of effect of pinealectomy on ovarian function: evidence for a time-dependent action.

Abstract: SummaryThe interrelationship between the rat pineal, ovary, and hypophysis was examined utilizing organ weight, histology, RNA content, and RNA:DNA ratio as an index of synthetic activity. Six weeks post-pinealectomy, no change in ovarian function was observed utilizing the above parameters. A time-dependent action of pinealectomy on ovarian activity is postulated. Following ovariectomy a significant increase in pineal weight was seen. This suggests the existence of a feedback mechanism between the pineal and anterior pituitary similar to that of other endocrine organs.