PRELIMINARY OBSERVATIONS ON THE REPRODUCTIVE EFFECTS OF THE PINEAL GLAND IN BLINDED, ANOSMIC MALE RATS

VGF (nonacronymic) is a 68-kDa protein encoded by the homonymous gene, which is expressed abundantly at the hypothalamus and has been involved in the control of metabolism and body weight homeostasis. Different active peptide fragments are generated from VGF, including TLQP-21. Circumstantial evidence has suggested that VGF might also participate in the control of reproduction. Yet its mechanisms of action and the eventual role of specific VGF-derived peptides on the hypothalamic-pituitary-gonadal (HPG) axis remain unknown. Herein we report a series of studies on the reproductive effects of TLQP-21 as evaluated in male rats by a combination of in vivo and in vitro analyses. Central administration of TLQP-21 induced acute gonadotropin responses in pubertal and adult male rats, likely via stimulation of GnRH secretion, as documented by static incubations of hypothalamic tissue. In addition, in pubertal (but not adult) males, TLQP-21 stimulated LH secretion directly at the pituitary level. Repeated central administration of TLQP-21 to pubertal males subjected to chronic undernutrition was able to ameliorate the hypogonadotropic state induced by food deprivation. In contrast, chronic administration of TLQP-21 to fed males at puberty resulted in partial desensitization and puberty delay. Finally, in adult (but not pubertal) males, TLQP-21 enhanced hCG-stimulated testosterone secretion by testicular tissue in vitro. In summary, our data are the first to document a complex and multifaceted mode of action of TLQP-21 at different levels of the male HPG axis with predominant stimulatory effects, thus providing a tenable basis for the (direct) reproductive role of this VGF-derived peptide.

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Morphometric features of rat pinealocytes in conditions of chronic ethanol intoxication

Reports of Morphology ◽

10.31393/morphology-journal-2021-27(1)-03 ◽

2021 ◽

Vol 27 (1) ◽

pp. 17-22

Author(s):

V.V. Pshychenko ◽

V.S. Cherno

Keyword(s):

Pineal Gland ◽

Morphological Changes ◽

Alcohol Intoxication ◽

Morphometric Parameters ◽

Chronic Ethanol ◽

Male Rats ◽

Control Group ◽

Ethanol Intoxication ◽

Chronic Ethanol Intoxication ◽

Experimental Group

Ethanol has chronobiological effects, which are associated with inhibition of melatonin synthesis and secretion and disruption of the sleep-wake cycle. Ethanol is known to cause sleep fragmentation due to frequent awakenings, prolong wakefulness, and reduce the duration of the slow sleep phase. At the same time, changes in the morphology of the pineal gland under chronic exposure to ethanol remain poorly studied. Of particular interest are changes in the basic morphometric parameters of pinealocytes, because they are a marker of the functional state of the pineal gland. The aim of the study was to morphometrically study the features of morphological changes in rat pinealocytes in the physiological norm and in chronic ethanol intoxication. To achieve this goal, we used 20 laboratory male rats: a control group and an experimental group. The control group was under standard vivarium conditions. For the experimental group, alcohol intoxication was modeled by injecting a 40% ethanol solution at the rate of 12 mg/kg of body weight intragastric 4 times a day. The morphometric parameters of pinealocytes were studied on day 30 from the start of the study. According to the results of morphometric measurements, a significant increase in the parameters of light pinealocytes and a decrease in the parameters of dark cells were established. It was determined that the average values of the cytoplasm area of light pinealocytes increase by 54.55% (p<0.05), the area of the nucleus increases by 61.32% (p<0.05), and the area of the nucleolus by 32.84% (p<0.05) compared with the control group. The area of the cytoplasm of dark pinealocytes decreases by 27.2% (p<0.05), and the area of the nucleus by 37.33% (p<0.05). Changes in the ratio of light and dark pinealocytes were also noted. An increase in the number of active light cells by 8.17% was found. The detected morphometric changes indicate high functional activity of cells, which has a compensatory nature in response to apoptosis of pinealocytes.

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Reproductive effects of prenatal exposure to 5-bromo-2′-deoxyuridine on male rats

Reproductive Toxicology ◽

10.1016/s0890-6238(96)00195-5 ◽

1997 ◽

Vol 11 (1) ◽

pp. 37-45 ◽

Cited By ~ 9

Author(s):

Tetsuji Nagao ◽

Yoshiaki Saito ◽

Chiaki Watanabe ◽

Kiyoshi Imai

Keyword(s):

Prenatal Exposure ◽

Male Rats ◽

Reproductive Effects

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Leptin, neuropeptide Y (NPY), melatonin and zinc levels in experimental hypothyroidism and hyperthyroidism: relation with melatonin and the pineal gland

Hormone Molecular Biology and Clinical Investigation ◽

10.1515/hmbci-2018-0009 ◽

2018 ◽

Vol 0 (0) ◽

Author(s):

Abdulkerim Kasım Baltaci ◽

Rasim Mogulkoc

Keyword(s):

Pineal Gland ◽

Neuropeptide Y ◽

Thyroid Dysfunction ◽

Hormone Receptors ◽

Thyroid Stimulating Hormone ◽

The Other ◽

Male Rats ◽

Blood Samples ◽

Experimental Animals ◽

Zinc Levels

Abstract Background Melatonin, an important neurohormone released from the pineal gland, is generally accepted to exercise an inhibitor effect on the thyroid gland. Zinc mediates the effects of many hormones and is found in the structure of numerous hormone receptors. Aim The present study aims to examine the effect of melatonin supplementation and pinealectomy on leptin, neuropeptide Y (NPY), melatonin and zinc levels in rats with hypothyroidism and hyperthyroidism. Methods This study was performed on the 70 male rats. Experimental animals in the study were grouped as follows: control (C); hypothyroidism (PTU); hypothyroidism + melatonin (PTU + M); hypothyroidism + pinealectomy (PTU + Pnx); hyperthyroidism (H); hyperthyroidism + melatonin (H + M) and hyperthyroidism + pinealectomy (H + Pnx). Blood samples collected at the end of 4-week procedures were analyzed to determine melatonin, leptin, NPY and zinc levels. Results It was found that thyroid parameters thyroid stimulating hormone (TSH), free triiodthyronine (FT3), free thyroxine (FT4), total T3 (TT3) and total T4 (TT4) decreased in hypothyroidism groups and increased in the groups with hyperthyroidism. The changes in these hormones remained unaffected by melatonin supplementation and pinealectomy. Melatonin levels rose in hyperthyroidism and fell in hypothyroidism. Leptin and NPY levels increased in both hypothyroidism and hyperthyroidism. Zinc levels, on the other hand, decreased in hypothyroidism and pinealectomy, but increased in hyperthyroidism. Conclusion The results of the study demonstrate that hypothyroidism and hyperthyroidism affect leptin, NPY, melatonin and zinc values in different ways in rats. However, melatonin supplementation and pinealectomy do not have any significant influence on the changes occurring in leptin, NPY and zinc levels in thyroid dysfunction.

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Reproductive toxicity and tissue concentrations of 3,3',4,4'-tetrachlorobiphenyl (PCB 77) in male adult rats

Human & Experimental Toxicology ◽

10.1177/096032719801700305 ◽

1998 ◽

Vol 17 (3) ◽

pp. 151-156 ◽

Cited By ~ 1

Author(s):

A S Faqi ◽

P R Dalsenter ◽

W Mathar ◽

B Heinrich-Hirsch ◽

I Chahoud

Keyword(s):

Adult Male ◽

Weight Control ◽

Reproductive Toxicity ◽

Serum Testosterone ◽

Male Rats ◽

Testis Weight ◽

Adult Rats ◽

Male Adult ◽

Reproductive Effects ◽

Investigation Period

1 The aim of this study was to ascertain the reproductive effects of PCB 77 on adult male rats and to determine its concentration in the liver and testis. Adult male rats (n=15/group) were treated subcutaneously with a singledoseof18 mg/kgbw(PC18)orwith60 mg/kg bw (PC60). The substance was dissolved in a 10 ml volume of peanut oil/kg. Control rats received the same volume of the vehicle. The reproductive effects as well as the concentration of PCB 77 in the liver and testis were investigated 1, 4 and 8 weeks after treatment. 2 In both groups, the daily sperm production (DSP; 6106) remained permanently reduced in the PC18 as well as in the PC60 groups throughout the entire investigation period (DSP week 8: control: 31+7; PC18: 22+5; PC60: 20+7). The sperm number (6106) per cauda epididymis was affected only at the 1st and 4th week after treatment (control week 1: 211+67; PC18 week 1: 135+62; PC60 week 1: 142+49). Moreover, a significant increase in the percentage of abnormal sperm was observed 4 weeks following treatment in the PC18 and PC60 groups and 8 weeks after treatment in the PC60 group. Abnormal tails were the most frequent changes observed. 3 The relative testicular and prostata weights (g) were slightly increased in the PC60 group at the 1st and 4th week following treatment (testis weight: control/I: 0.46+0.02; PC60/I: 0.51+0.03). 4 The serum testosterone concentrations and effects on testis morphology were not reported. 5 The maximum concentration of PCB 77 was detected in the liver and testis 1 week after treatment. The concentration declined 4 weeks after treatment in both organs, but still a significant amount of PCB 77 was detectable in the liver as well as in the testis 8 weeks after treatment. 6 The results demonstrate that PCB 77 affects sperm variables when applied to adult rats and that the elimination of PCB 77 in the testis parallels that of the liver.

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Diurnal rhythms of immunoreactive N-acetylserotonin and melatonin in the serum of male rats

Acta Endocrinologica ◽

10.1530/acta.0.0950571 ◽

1980 ◽

Vol 95 (4) ◽

pp. 571-576 ◽

Cited By ~ 28

Author(s):

S. F. Pang ◽

M. K. Yip ◽

H. W. Liu ◽

G. M. Brown ◽

H. W. Tsui

Keyword(s):

Pineal Gland ◽

Ethyl Acetate ◽

Diurnal Rhythm ◽

Protein Precipitation ◽

Male Rats ◽

Diurnal Rhythms ◽

Rat Serum

Abstract. Immunoreactive N-acetylserotonin and melatonin in rat serum were extracted by ethyl acetate at ≤ pH 3 and chloroform at ≥ pH 10. respectively, following protein precipitation and were quantified by radioimmunoassays. There were diurnal rhythms of N-acetylserotonin and melatonin in the serum of rats (housed in 121/12d; lights on from 06.00–18.00 h for two weeks). Serum melatonin levels at 20.00–04.00 h are higher than those at 08.00–16.00 h. Serum N-acetylserotonin levels were, however, higher at 24.00–08.00 h and lower at 12.00–20.00 h. The concentration of N-acetylserotonin in individual samples ranged from a minimum of 0.45 ng/ml at 12.00 h to a maximum of 2.78 ng/ml at 08.00 h. The diurnal study on N-acetylserotonin levels in the rat serum was repeated and a similar result was obtained. The findings of the presence of N-acetylserotonin in the rat serum and a diurnal rhythm of serum N-acetylserotonin are in keeping with the notions that N-acetylserotonin may be secreted by the pineal gland and that N-acetylserotonin may be another indole with hormonal activities.

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