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C Haldar

Publications and source records attributed to C Haldar.

At least 37 records · Page 2Linked to original sources
PubMed1996

Harderian gland function of Indian tropical palm squirrel, Funambulus pennanti.

The Harderian gland (HG) of the Indian palm squirrel, F. pennanti, is composed of acini of a single type of simple columnar cells with uniform-sized lipid droplets and porphyrin (P) in the lumen. Morphologically it presented no sexual dimorphism except for the HG weight which revealed that males are acyclic. Circadian study of Harderian gland porphyrin (HG-P), plasma melatonin, (aMT) and testosterone showed a characteristic two peak cyclicity. In females, HG, HG-P and pineal gland weight, and plasma aMT presented an annual inverse relation. Circadian study in females only exhibited a two peak cyclicity of HG-P, plasma aMT, and estradiol. Pinealectomy (PX) and harderianectomy (HGX) revealed increased HG weight and gonad weight in males. Gonadectomy (GX), on the other hand, had no effect on HG in males. PX in females brought almost a similar effect as noted for males, but HGX had no effect on ovarian weight. GX, interestingly, reduced HG weight and P concentration. Daily evening (4:30-5:00) administration of aMT and 5-methoxytryptamine (5-MT) in males reduced HG weight and HG-P content only in aMT-treated male and female squirrels, thereby suggesting that HG-P is perhaps negatively regulated by pineal gland production and vice versa. Injections of gonadotropin and steroids during the sexually inactive phase showed no effect on HG-P content in both sexes. Short photoperiod (SP) in both sexes stimulated pineal weight without affecting HG weight, while long photoperiod (LP) increased HG-P but reduced the plasma aMT level again without affecting HG-P content. Continuous dark (CD) decreased HG-P, whereas continuous light was ineffective without effecting HG weight in both sexes. In conclusion, HG in this rodent is functionally an important gland having diverse physiological effect in both sexes sometimes with a very clear HG-pineal-gonad relationship.

5-Methoxytryptamine↗
PubMed1996

Diurnal variations in circulating estradiol, testosterone, melatonin and harderian gland porphyrin concentration in Indian palm squirrel, Funambulus pennanti.

A two-peak cyclicity in the plasma level of melatonin, estradiol/testosterone and Harderian porphyrin was noted in F. pennanti. An inverse relationship of Harderian porphyrin with plasma melatonin and a direct relation of it with plasma estradiol/testoserone level were also observed, suggesting that the variation of Harderian, porphyrin concentration may be under the control of both, circulating melatonin and gonadal steroids.

Animals↗
PubMed1993

Ontogeny, circadian rhythm pattern, and hormonal modulation of 5 alpha-dihydrotestosterone receptors in the rat pineal.

Some physiological parameters of pineal 5 alpha-dihydrotestosterone receptor in the rat such as ontogeny, circadian rhythm pattern, and its modulation by various neuropeptides and neurotransmitters which have profound influences on the pineal hormone melatonin were examined. Pineal 5 alpha-dihydrotestosterone receptors measured at different ages of the animal revealed that on day 10 both cytosolic receptor (CR) and nuclear receptor (NR) levels were high. With growth and development both groups of receptors declined and during puberty started again to rise. During adulthood both receptors were high; however, NR rose further with full maturation. Both groups of receptors showed circadian rhythmicity. While the CR was significantly higher at 6.00 h than at any time point through 24 h, the NR peaked at 18.00 h when the difference between both groups was maximum. Castration caused significant increment of NR. Treatment of castrated animals with a low dose of testosterone propionate (0.25 mg) significantly stimulated both receptor groups, while treatment with a high dose (2.5 mg) failed to do so. Treatment with various substances such as antiandrogen, opioids, neuropeptides, and neurotransmitters significantly modulated the pineal androgen receptor population: cyproterone acetate and monosodium glutamate suppressed CR; growth hormone releasing hormone increased NR; growth hormone release inhibiting hormone had no significant effects on either group of receptors; exogenous melatonin and norepinephrine increased NR; beta-endorphin increased only NR, but methionine enkephalin stimulated both, and epithalamine had no significant effects on either group of receptors, but thymosin alpha 1 increased NR.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Photoperiodic response of pineal-thyroid axis of the female Indian palm squirrel, Funambulus pennanti.

Effect of short (SP: 10 L: 14 D: Light: Dark) and long (LP: 14 L: 10 D) photoperiod was tested on pineal-thyroid axis in a tropical seasonally breeding rodent F. pennanti during sexually regressive phase of reproduction. SP reduced thyroid weight and plasma thyroxine (T4) as well as increased melatonin (aMT) while pinealectomy (Px) prevented such an effect of SP. LP and Px plus LP had no significant effect on thyroid activity when compared with their respective controls. These results suggest that SP stimulated pineal activity which increased the concentration of aMT, hence inhibited thyroid gland activity. However, the plasma aMT concentration under LP regime had no significant difference from controls, as the ambient photoperiodic length (13.6 hr) was almost similar to the experimental one (14.0 hr). It is suggested that being innervated from the same ganglion (SCG) which conveys photic stimuli to the pineal gland, the thyroid gland like the pineal is also under the influence of photoperiodic responses. Further pineal/melatonin also influences thyroid function indirectly.

Animals↗
PubMed1992

Response of CFU-GM (colony forming units for granulocytes and macrophages) from intact and pinealectomized rat bone marrow to murine recombinant interleukin-3 (rIl-3), recombinant granulocyte-macrophage colony stimulating factor (rGM-CSF) and human recombinant erythropoietin (rEPO).

The present study provides evidence, for the first time, of a role of the pineal gland in the proliferation of CFU-GM under the influence of different cytokines. The degree of colony formation in different cytokine groups was evaluated after 24 h, 3, 7 and 10 days. The colony growth in the present type of bone marrow cell cultures slows after the 10th day and ceases after the 14th day of incubation. The results show that rGM-CSF and the combination of rGM-CSF with rIl-3 and with rEPO stimulate the colony formation of granulocytes and macrophages. A 50% general reduction in the colony number was noted in the pinealectomy group. Their pattern of response to the different cytokines was similar to that of the intact group. It is suggested that the pineal activity has a physiological role in important aspects of host defence mechanisms, such as the proliferation of CFU-GM.

Animals↗
PubMed1992

Effect of the pineal gland on circadian rhythmicity of colony forming units for granulocytes and macrophages (CFU-GM) from rat bone marrow cell cultures.

The present study provides evidence that the pineal gland has a physiological role in the proliferation of colony forming units for granulocytes and macrophages (CFU-GM). A biphasic circadian rhythm of CFU-GM proliferation in rat bone marrow cell cultures (BMC) from intact animals peaking at 0600 and 1800 was observed. Pinealectomy (Px) at 1600 obliterated the circadian rhythm patterns of CFU-GM. Afternoon injections of melatonin (1630, 20 micrograms/per day for 10 days) to Px animals restored the rhythmicity. When pinealectomy was done at 0800, the morning peak remained unaltered and the colony number at 1800 was higher than that found in the afternoon Px animals. In conclusion, the pineal gland or its main hormone melatonin seems to have a regulatory role in the proliferation of CFU-GM in rat BMC. Further, the expression of the activity of CFU-GM in rat BMC depends on the time when pinealectomy is done or melatonin is substituted.

Animals↗
PubMed1992

Gonado-modulatory effects of high humidity is pineal dependent in Indian palm squirrel Funambulus pennanti (Wroughton).

F. pennanti presented a clear biphasic pineal mediated seasonal sexual cycle. This sexual cycle was essentially characterised by a very short period of sexual quiescence with an arrest of spermatogenesis during October-November. A small but clear decrease in sexual activity was also observed during March-April. This decrease in sexual activity, however, had no quantifiable effect on spermatogenesis. Sexual recrudescence was observed from December-January. The testes remained sexually active from January till September. Almost an inverse relationship was observed between pineal and testicular weight. Pinealectomy, however, prevented naturally induced gonadal regression during both the periods, i.e. September-November and February-April. Exposure of animals to high RH (80 +/- 4%) during sexually active phase induced a steep regression in testicular weight of sham-operated animals even in the presence of gonad stimulatory long photoperiod (16L:8D) and high temperature (40 degrees +/- 5 degrees C) while exposure of animals to moderate RH (65 +/- 5%) during sexual regression phase partially prevented testicular regression even in presence of inhibitory short photoperiod (11L:13D) and normal environmental temperature (30 degrees +/- 5 degrees C). Pinealectomized animals, neither exhibited testicular regression in February-March nor had involuted testes in September-October, thus, suggesting that the effect of humidity is mediated via the pineal gland.

Animals↗
PubMed1990

Annual pineal and testicular cycle in the Indian jungle bush quail, Perdicula asiatica, with reference to the effect of pinealectomy.

The annual testicular cycle of Perdicula asiatica has a single peak which appears to be under the dual influence of the environment and the pineal gland. An inverse relationship was noted between pineal gland and testicular weight cycle. Pinealectomy, after 60 days, retarded testicular growth in the progressive phase, inhibited activity of the gonad in the active phase, and accelerated gonadal regression in the regressive phase. This complete study of short-term pinealectomy effects on the annual testicular cycle of a tropical bird for the first time reflects both the essentialness of the pineal gland to the maintenance of proper testicular cyclicity under natural environment conditions and the progonadotropic nature of the pineal gland.

Animals↗
PubMed1990

Sex- and age-dependent nature of the cytoplasmic 5 alpha-dihydrotestosterone (DHT) binding site/receptor in bovine pineal gland.

Recent research has justified the presumption that the pineal gland plays a role in the regulation of the gonadal system in mammals. Evidence also exists for androgen receptors in pinealocytes. In the current study, our approach has been to assess the age- and sex-dependent nature of 5 alpha-DHT receptors in bovine pineal. Although no significant difference was noted between various groups of bulls, cows, peripuberal cows, and calves (male) for pineal weight, the cytoplasmic 5 alpha-DHT binding site/receptor content in the pineal gland differed significantly. While the males had a low androgen receptor concentration in the pineal (46 fmol/pineal), the females showed the highest (442 fmol/pineal). The peripuberal females without calves and calves (male) presented a 5 alpha-DHT receptor content in between (225 fmol/pineal; 138 fmol/pineal). When the data were related to unit weight of pineal tissue, the difference still existed. It is suggested that the concentration of cytoplasmic 5 alpha-DHT receptors reflects the cellular activity and they are inversely related. Further, low cytoplasmic receptors also indicate that most of it is confined to the nuclear sites, as generally suggested for other androgen-dependent tissues. In the light of these suggestions, it is possible that lowest cytosolic 5 alpha-DHT receptor concentration in the males, in reality, reflects a higher degree of cellular function and a high concentration of the receptors in the nuclear site. Similarly, the peripuberal cows and calves perhaps have more cellular activity in the pineal than the mature cows. The current investigation, for the first time, by directly estimating the androgen receptors/binding site in the bovine pineal gland, demonstrates the sex- and age-dependent nature.

Aging↗
PubMed1989

Effect of pinealectomy on annual testicular cycle of Indian chequered water snake, Natrix piscator.

Pinealectomy for 60 days (noted every month of the year), in the tropical Indian chequered water snake. Natrix piscator, caused inhibition of testicular growth during late progressive and active phases and retarded the rate of regression during regressive phase; during sexually inactive phase the testes remain partially active. The weight of the accessory sex organs, vas deferens, and kidney (along with the renal sex segment activity) followed the same pattern as that of the testes. Thus, it may be concluded that the pineal gland of this ophidian participates in the regulation of seasonal testicular cycle, probably via the hypothalamo-hypophyseal axis, and hence the effects of pinealectomy are seasonal and a reproductive phase-dependent phenomenon.

Animals↗
PubMed1989

Effect of pinealectomy and 5-methoxyindoles on Harderian gland activity of the Indian Jungle bush quail Perdicula asiatica.

The present study reveals that the annual Harderian gland weight cycle of P. asiatica has a direct relationship with the testicular cycle and an inverse relationship with the pineal gland cycle. Pinealectomy resulted in a significant decrease of the Harderian gland weight during the recurdescence (March-May) and active (April-June) phases. Subcutaneous implantation of melatonin (aMT) and 5-methoxytryptamine (MT) brought about a significant reduction during the recrudescence and active phases whereas subcutaneous injections of aMT, MT and 5-methoxytryptophol (ML) reduced Harderian gland weight effectively during the morning as well as in the evening hours in the active and inactive phases.

5-Methoxytryptamine↗
PubMed1988

Pineal gland and humidity effects on testicular function of the Indian palm squirrel, Funambulus pennanti.

The effect of two different conditions of humidity (80 +/- 5% and 40 +/- 5%) under stimulatory photoperiod (14L/10D) and high temperature (38 +/- 2 degrees C) was studied on the testes and accessory sex organs of the Indian palm squirrel, Funambulus pennanti, during the sexually active phase. High humidity (80 +/- 5%) reduced significantly the testes weight of the sham-operated animals as compared to the controls under natural environmental conditions but had no effect on that of pinealectomized animals. Moderate humidity (40 +/- 5%) did not affect the testes of sham-operated as well as pinealectomized animals, as compared to the respective controls. The seminal and prostatic weights showed no significant difference in high or moderate humidity conditions. However, the epididymal weight of the animals exposed to high humidity was significantly reduced in sham-operated animals only. Thus, these results indicate that the pineal gland may be implicated in mediating the humidity information to control the male gonadal function in the Indian palm squirrel, Funambulus pennanti.

Animals↗
PubMed1988

Effect of melatonin and 5-methoxytryptamine administration on the testis and pineal gland activity of the fresh-water snake, Natrix piscator.

Effects of melatonin (aMT) and 5-methoxytryptamine (MT) were studied on the testicular activity cycle of the fresh-water snake, Natrix piscator. The subcutaneous implantation and the injections (morning as well as evening) of these two methoxyindoles prevented testicular recrudescence, retarded the testicular active phase, and accelerated the rate of regression of testes, while having no effect on the inactive testes. Contrary to this, these two compounds increased the pineal gland weight during different reproductive phases. These results revealed that both aMT and MT, whether they were continuously released through silastic capsule implants or administered through daily periodic injections, produced inhibitory effects on the testicular function.

5-Methoxytryptamine↗
PubMed1988

Effect of 5-methoxyindoles on testicular function of the Indian jungle bush quail Perdicula asiatica.

Melatonin (aMT) implantation during testicular inactive phase (January-March) brought an early initiation of testicular development in Perdicula asiatica. However, during the recrudescence (March-May), active (April-June), and regressive (May-July-September) phases both aMT and 5-methoxytryptamine (MT) implantation had inhibited testicular weight and activity significantly. Subcutaneous injections of aMT, MT and 5-methoxytryptophol (ML) during morning (7.30 a.m.-8.00 a.m. and evening (4.30 p.m.-5.00 p.m.) could not bring about any significant effect on the weight or activity of the testes during the inactive (January-February) phase, while inhibited testicular weight and activity during the active (May-June) phase when administered in the morning as well as in the evening hours.

5-Methoxytryptamine↗