Effect of pinealectomy on photoperiodic gonadal response of Indian palm squirrel, Funambulus pennanti

1987 ◽  
Vol 65 (4) ◽  
pp. 833-836 ◽  
Author(s):  
C. Haldar-Misra ◽  
M. Srivastava
Keyword(s):  
Pineal Gland ◽  
Experimental Period ◽  
Short Photoperiod ◽  
Gonadal Activity ◽  
Reproductive Axis ◽  
Testicular Regression ◽  
Long Photoperiod

The role of the pineal gland in mediating the effects of photoperiod on the reproductive axis is not well established in tropical mammals. Indian palm squirrels (Funambulus pennanti) were exposed to experimental long (16L:8D) and short (6L:18D) photoperiods. It was observed that the testes regressed in response to short photoperiod, while during the long photoperiod the gonads were active. When squirrels were maintained for a long experimental period (130 days) under the short photoperiodic schedule (6L:18D), gonadal regrowth eventually occurred even though the photoperiod was the same one that initially induced testicular regression. Pinealectomized animals maintained the gonadal activity even in short photoperiod, suggesting that the effect of photoperiod is mediated through the pineal gland.

CIRCA-ANNUAL RHYTHMS OF PROLACTIN SECRETION IN EWES AND THE EFFECT OF PINEALECTOMY

1980 ◽  
Vol 84 (1) ◽  
pp. 83-89 ◽  
Author(s):  
C. J. MUNRO ◽  
K. P. McNATTY ◽  
L. RENSHAW
Keyword(s):  
Plasma Concentration ◽  
Pineal Gland ◽  
Seasonal Variations ◽  
Reproductive Tract ◽  
Plasma Concentrations ◽  
Prolactin Secretion ◽  
Transitional Period ◽  
Short Photoperiod ◽  
Winter Period ◽  
Long Photoperiod

Changes in the plasma concentration of prolactin in intact, pinealectomized, shampinealectomized, ovariectomized and hysterectomized ewes were investigated over a period of 11 months. The concentrations of prolactin were consistently low (<20 ng/ml) during the winter months (short photoperiod) in the intact, sham-pinealectomized, ovariectomized and hysterectomized animals. In contrast, the concentrations of prolactin were consistently raised (> 50 ng/ml) during the summer months (long photoperiod) in the same groups. During the transitional period from winter to summer the concentrations of prolactin were correlated with the reproductive status of the animals. In the pregnant animals, the prolactin concentrations increased from low values during pregnancy to high values at parturition. During lactation, the concentrations of prolactin in these animals remained high, although they were lower than those found subsequently during the summer months when the ewes were no longer lactating. In the non-pregnant ewes (i.e. the ovariectomized and hysterectomized animals), the prolactin concentrations increased more gradually during the transitional period from winter to summer than was the case in the parturient animals. In the pinealectomized ewes, the plasma concentrations of prolactin were raised throughout the year, irrespective of whether the animals were pregnant, lactating or in anoestrus. In these animals, the only occasion when prolactin concentrations were consistently low was during the mid-winter period, although they were also low at times during the period of oestrous activity. It was concluded that the circa-annual pattern of prolactin concentrations in ewes is primarily determined by the photoperiod, and that the pineal gland in the ewe is an important translator of the photoperiod. Parturition and suckling have important, but secondary, influences. Moreover, it was concluded that the secretions from the reproductive tract and the seasonal variations in temperature normally have little influence by themselves on the circa-annual rhythm of prolactin.

The role of estrogen and progesterone in the regulation of reproductive behaviour in female ring doves (Streptopelia risoria) under long vs. short photoperiods

1976 ◽  
Vol 54 (9) ◽  
pp. 1409-1422 ◽  
Author(s):  
N. R. Liley
Keyword(s):  
Hormone Treatment ◽  
Reproductive Behaviour ◽  
Egg Laying ◽  
Nest Building ◽  
Short Photoperiod ◽  
Streptopelia Risoria ◽  
Ring Doves ◽  
Long Photoperiod ◽  
Marked Tendency

Female ring doves held under long (16 h per day) or short (8 h per day) photoperiods were treated daily for 15 days with saline, estrogen, or progesterone, alone or in combination. Seven days after the start of hormone therapy females were placed with reproductively active males for 4 h per day for 9 days. There was no difference in egg-laying, courtship, and nest-building by control birds under the two photoregimes.Ovarian follicles remained small in all birds receiving hormone treatment. Oviducts of birds receiving progesterone alone remained small in the short-photoperiod group, but at long photoperiods oviducts became enlarged. Estrogen stimulated oviduct growth at both photoperiods. The combined hormone treatment resulted in considerably greater oviduct development than estrogen alone, and in this case the oviducts of birds under long photoperiod were significantly heavier than those of short-photoperiod birds.Female soliciting and nest-building activity remained low in progesterone-treated females under short photoperiod, but increased rapidly under long photoperiod. Birds treated with estrogen and estrogen and progesterone performed considerable soliciting and nest-building. There was a marked tendency for birds under long-photoperiod conditions to be more active in nest-oriented behaviour. Copulatory behaviour by the female (begging and sexual crouch) occurred infrequently in all hormone-treated birds.

Effects of photoperiod, pinealectomy and castration on body weight and daily torpor in Djungarian hamsters (Phodopus sungorus)

1985 ◽  
Vol 106 (3) ◽  
pp. 367-375 ◽  
Author(s):  
P. M. Vitale ◽  
J. M. Darrow ◽  
M. J. Duncan ◽  
C. A. Shustak ◽  
B. D. Goldman
Keyword(s):  
Body Weight ◽  
Pineal Gland ◽  
Body Weight Loss ◽  
Phodopus Sungorus ◽  
Daily Torpor ◽  
Weight Changes ◽  
Reproductive Axis ◽  
Testicular Regression ◽  
Autumn And Winter ◽  
Short Days

ABSTRACT During the autumn and winter Djungarian hamsters (Phodopus sungorus) exhibit regression of the gonads, development of a white winter pelage, loss of body weight and daily torpor. These seasonal events are largely regulated by changes in photoperiod. The present experiments were designed to examine the role of the testes and the pineal gland in photoperiodically induced daily torpor and body weight loss. Hamsters displayed a loss of body weight and daily torpor when exposed to a short-day photoperiod in a cold environment, but these phenomena did not occur in hamsters exposed to long days and cold. Testicular regression is probably a precondition for the display of torpor, since daily torpor was almost totally inhibited in hamsters which were exposed to short days and in which testosterone was administered from subcutaneous silicone elastomer implants. Nevertheless, decreased testosterone secretion alone is not a sufficient condition for induction of daily torpor, since torpor was rarely observed in hamsters exposed to long days, even after castration. In addition to decreased testicular activity, the pineal gland is also involved in establishing conditions for torpor. Thus, pinealectomy prevented the display of torpor by castrated hamsters exposed to short days. Body weight changes were also found to be influenced by both testicular hormone and pineal activity. These observations indicate that the pineal gland is involved, as a part of the photoperiodic mechanism, in regulating a variety of physiological events and that some of these actions of the pineal are independent of its extensively described actions on the reproductive axis. J. Endocr. (1985) 106, 367–375

Naloxone-induced secretion of LH in the male Syrian hamster: modulation by photoperiod and gonadal steroids

1985 ◽  
Vol 106 (2) ◽  
pp. 243-248 ◽  
Author(s):  
A. C. Roberts ◽  
M. H. Hastings ◽  
N. D. Martensz ◽  
J. Herbert
Keyword(s):  
Syrian Hamster ◽  
Serum Testosterone ◽  
Opiate Receptor ◽  
Gonadal Steroids ◽  
Endogenous Opiates ◽  
Serum Lh ◽  
Testicular Regression ◽  
Lh Release ◽  
Long Photoperiod

ABSTRACT The role of endogenous opiates in the regulation of photoperiodically induced testicular regression was studied in the male Syrian hamster. In reproductively active hamsters exposed to a long photoperiod (LD; 16 h light: 8 h darkness) or to short days (SD; 8 h light: 16 h darkness) for 20 weeks or to SD after pinealectomy, administration of naloxone, a competitive opiate receptor antagonist, at doses of 2·5–20 mg/kg, significantly increased serum LH concentrations. In marked contrast, these doses of naloxone did not produce any change in LH levels in reproductively quiescent hamsters exposed to SD for 8 weeks. The influence of gonadal steroids on the LH response to naloxone was studied in hamsters castrated or castrated and implanted s.c with a capsule containing testosterone. Naloxone did not induce LH release in castrated hamsters maintained in LD or in SD, but this response was restored in LD but not SD when serum testosterone concentrations were maintained at levels similar to those observed in intact reproductively active hamsters. These results show that inhibition of reproduction by the photoperiod prevents naloxone-induced LH release in the male hamster. This lack of response to naloxone is not due, however, to the lower testosterone titres present in these animals compared with reproductively active animals. Responsiveness to naloxone can be restored when the animal is rendered insensitive to the inhibitory photoperiod either by removal of the pineal gland or by induction of photorefractoriness by extended exposure to SD. J. Endocr. (1985) 106, 243–248

Proliferation, apoptosis, and number of Sertoli cells in the Syrian hamster during recrudescence after exposure to short photoperiod†‡

2019 ◽  
Vol 102 (3) ◽  
pp. 588-597 ◽  
Author(s):  
Jesús Martínez-Hernández ◽  
Vicente Seco-Rovira ◽  
Ester Beltrán-Frutos ◽  
Concepción Ferrer ◽  
María Isabel Serrano-Sánchez ◽  
...  
Keyword(s):  
Syrian Hamster ◽  
Normal Population ◽  
Similar Rate ◽  
The Other ◽  
Short Photoperiod ◽  
Control Group ◽  
Bright Field ◽  
Testicular Regression ◽  
Testicular Recrudescence ◽  
Long Photoperiod

Abstract The Sertoli cell (Sc) has been described as a quiescent cell once the animal has reached sexual maturity. Syrian hamster is an animal that displays testicular regression due to short photoperiod, during which process germ cells and Sc are removed through apoptosis. The aim of this work was to investigate histochemically whether the spontaneous testicular recrudescence processes after exposure to a short photoperiod lead to an increase in Sc proliferative activity in order to restore the normal population. Three spontaneous recrudescence groups were established: initial (IR), advanced (AR), and total (TR) recrudescence, which were compared with animal undergoing the regression process (mild: MRg, strong: SRg, and total: TRg) and animals in long photoperiod (Controls). Histological sections were submitted to histochemical techniques for detecting apoptotic and proliferative Sc with bright-field and fluorescence microscopy. For each group, the proliferative Sc index (PScI) and apoptotic Sc index (AScI), and the total number of Sc were obtained. The results revealed the existence of Vimentin+/TUNEL+ as well as Vimentin+/PCNA+ cells. The PScI was significantly higher in TRg and IR than in the other groups. The AScI was only significantly higher in MRg and SRg with respect to the other groups. The total number of Sc increased among TRg, IR, and AR, reaching values similar to those of the Controls. In conclusion, the increase in Sc proliferation from final regression and recrudescence, accompanied by a similar rate of apoptosis to the Control group, is the cause of the restoration of the Sc population during spontaneous recrudescence.

scholarly journals Circadian regulation and molecular role of the Bsx homeobox gene in the adult pineal gland

2019 ◽  
Vol 68 (2) ◽  
Author(s):  
Mikkel B. Carstensen ◽  
Henrik Hertz ◽  
Tenna Bering ◽  
Morten Møller ◽  
Kristian Rohde ◽  
...  
Keyword(s):  
Pineal Gland ◽  
Homeobox Gene ◽  
Circadian Regulation

Seasonal changes of SP and NKA in frontal cortex, striatum and testes in the rat. Role of maternal pineal gland

Peptides ◽  
2004 ◽  
Vol 25 (6) ◽  
pp. 997-1004 ◽  
Author(s):  
N Vázquez Moreno ◽  
L Debeljuk ◽  
E Dı́az Rodrı́guez ◽  
C Fernández Alvarez ◽  
B Dı́az López
Keyword(s):  
Pineal Gland ◽  
Frontal Cortex ◽  
Seasonal Changes

Possible role of serotonin and neuropeptide Y on the disruption of the reproductive axis activity by perfluorooctane sulfonate

2015 ◽  
Vol 233 (2) ◽  
pp. 138-147 ◽  
Author(s):  
S. López-Doval ◽  
R. Salgado ◽  
B. Fernández-Pérez ◽  
A. Lafuente
Keyword(s):  
Neuropeptide Y ◽  
Perfluorooctane Sulfonate ◽  
Reproductive Axis
Sign in / Sign up

Export Citation Format

Share Document