Palm Squirrel Research Articles

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.

Suppression of annual testicular development in Indian Palm squirrel, Funambulus pennanti by 8 hr temporal relationship of serotonin and dopamine precursor drugs.

Daily injections of 5-HTP (5-hydroxytryptophan, serotonin precursor) and L-DOPA (L-Dihydroxyphenylalanine, dopamine precursor) given 8 hour apart inhibited normal testicular growth in seasonally breeding Indian Palm Squirrel, Funambulus pennanti leading to complete gonadal atrophy, which was maintained till the end of the study. HCG administration induced higher degree of gonadal development but, when the two treatments (HCG + 8 hr relationship of 5-HTP and L-DOPA) were given simultaneously no significant difference was observed compared to control. Results indicate that induced suppression of gonadal function in a fashion similar to seasonal regression leading to non-breeding condition is the consequence of specific phase relationship (8 hr) between serotonergic and dopaminergic activities and not due to Serotonin or dopamine alone. This suggestion gets support from the finding that gonadal condition of squirrels receiving only 5-HTP (5-HTP control) or L-DOPA (DOPA control) was not different from control and exhibited normal testicular growth. It also seems that neurotransmitter precursor drugs given 8 hr apart possibly inhibited the activity of neuroendocrine-gonadal axis since this effect was overpowered by stimulatory effect of gonadotrophin. The findings strongly support the hypothesis that specific phase relation of circadian serotonergic and dopaminergic oscillations account for seasonal reproductive conditions.

Elimination of testicular regression by 12-hr temporal relationship of serotonergic and dopaminergic activity in Indian Palm Squirrel,Funambulus pennanti

Specific temporal relationship (12-hr) of serotonin and dopamine activity was induced by precursor drugs (5-HTP and L-DOPA) in Indian Palm Squirrel Funambulus pennanti during testicular regression phase. This treatment established breeding condition unlike control, which experienced complete atrophy of testes and accessory sex organs. It is obvious that seasonal testicular regression of Indian Palm Squirrel can be eliminated by 12 hr relation of 5-HTP and L-DOPA, which is not a pharmacological effect but actually is an alteration of seasonality in this annually breeding subtropical mammal. It may be concluded that specific phase relation (12-hr) between circadian serotonergic and dopaminergic oscillations may induce breeding condition in regressing gonad of Indian Palm Squirrel during post-reproductive phase of annual gonadal cycle. It is also suggested that inspite of the different environmental factors (photoperiod, humidity etc.) used by different species to time their annual reproduction, basic regulatory mechanism of seasonality appears to be the same, i.e., temporal synergism of neurotransmitter activity.

Ecofactors and effect of pinealectomy in regulation of seasonal testicular cycle in the Indian palm squirrel,Funambulus pennanti

Abstract The Indian palm squirrel, Funambulus pennanti showed a seasonal testicular cycle characterized by a short period of sexual quiescence with arrest of spermatogenesis in November when daylength and temperature were decreasing. The period of sexual recrudescence started from December when daylength and temperature were minimal and humidity was changing. The testes remained sexually active during rest of the annum. The accessory sex organs as judged by their weight and fructose level in seminal vesicle, acid phosphatase activity in prostate gland and glycerylphosphoryl choline in epididymis followed the pattern of testes. An inverse relationship between the pineal and testes weight was observed. The pinealectomized squirrels (after 60 days) presented an active testes throughout the year. It may be suggested that in the absence of the pineal the squirrels were unable to respond to environmental cues, and thus maintained themselves sexually active. Due to differential threshold level of testosterone for the accessory sex organs, pinealectomy had no effect on the prostate gland and seminal vesicle while epididymal weight and its glycerylphosphoryl choline content were higher in pinealectomized animals. The above results indicate that the pineal gland of this tropical rodent mediates the environmental information for the regulation of its annual testicular cyclicity.

Temporal synergism of neurotransmitter affecting drugs and seasonal reproductive responses of Indian Palm Squirrel,Funambulus pennanti

Daily injections of L-dihydroxyphenylalanine (L-DOPA, dopamine precursor) given 12 hour after 5-hydroxytryptophan (5-HTP, serotonin precursor) eliminated annual testicular regression in seasonally breeding sub-tropical Palm Squirrel that undergoes seasonal changes in responsiveness to day-length and humidity. Other temporal relations (L-DOPA given 0, 4, 8, 16 and 20 hours after 5-HTP administration) decreased/delayed the rate of regression and maintained the reproductive system at intermediate level. 12-hour-relation maintained full breeding condition (maximum gonad and accessory sex organs) unlike control, which exhibited complete atrophy of primary and accessory sex organs. It seems likely that these injections entrained the circadian serotonergic and dopaminergic oscillations and the interaction/phase relation of these two systems through their many circadian expressions (neural/hormonal) accounts for the seasonal interpretation of environmental factors. It is suggested that response in the present study is not a pharmacological effect of drugs but temporal synergism of neural activities affected the seasonality of reproduction as only 12-hour-relation of 5-HTP and L-DOPA maintained breeding activity during post reproductive phase of annual gonad cycle in Palm Squirrel.

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.

Cadmium chloride-induced changes in hypothalamic 5-hydroxytryptamine, noradrenaline and dopamine levels in the Indian palm squirrel, Funambulus pennanti (Wroughton)

A single intraperitoneal injection of cadmium chloride (CdCl 2, 0.32 mg/kg body weight) was administered to 15 adult female palm squirrels ( Funambulus pennanti (Wroughton)) and the hypothalamic 5-hydroxytryptamine (5-HT), noradrenaline (NA) and dopamine (DA) levels were quantified on the 1st, 7th and 40th day. 5-HT levels significantly decreased on the 1st and 40th day but showed an increase on the 7th day. Similarly, NA levels significantly decreased after 1, 7 and 40 days of treatment, and DA levels decreased on the 1st and 7th day but insignificantly increased on the 40th day. This suggests that CdCl 2 interferes in the functioning of the hypothalamo-hypophyseal axis by impairing the hypothalamic 5-HT, NA and DA levels, which may in turn affect the physiology of the peripheral endocrine glands.

Effect of cadmium chloride on thyroid activity of the female Indian palm squirrel, Funambulus pennanti (Wroughton).

In humans, exposure to Cadmium (Cd) occurs primarily through inhalation and ingestion. Acute Cd inhalation results in pulmonary edema and respiratory tract irritation; while chronic inhalation causes fibrotic and emphysematous changes in lung tissue as well as damage of renal proximal tubules. Several workers have reviewed the toxic effects of Cd on mammals, including man. In laboratory animals Cd produced kidney damage, testicular necrosis and atrophy, brain hemorrhage, hypertension, liver damage and reduced growth. It also induced changes in the adrenal and thyroid gland in the rat. In this study, squirrels, Funambulus pennanti, were administered a single dose of CdCl/sub 2/ intraperitoneally, and their thyroid structure and radioiodine I/sup 131/ uptake were assessed.

Corrections in the names of rodent coccidia (Apicomplexa, Coccidiasina).

The following new taxonomic combinations are introduced for coccidia whose names were previously given erroneously: Dorisa bengalensis (Bandyopadhyay & Ray, 1982) n. comb. from the Indian palm squirrel Funambulus pennanti in India; Eimeria sicistae from the intestine of the birch mouse Sicista tianschanica in the USSR; E. hydrochaeri Carini, 1937 emend. from the capybara Hydrochaerus hydrochaerus in South America; Frenkelia sp. (Doby, Jeannes & Rault 1965) from the brain of the water vole Arvicola sapidus in Europe; Frenkelia sp. (Karstad, 1963) from the brain of the muskrat Ondatra zibethica in North America; Frenkelia sp. (Enemar, 1965) from the brain of the lemming Lemmus lemmus in Europe; Frenkelia sp. (Sebek, 1975) from the brain of the field mouse Apodemus flavicollis in Europe; and Sarcocystis sp. (Ryan, Wyand & Nielsen, 1982) from the skeletal muscles of the muskrat Ondatra zibethica in North America.

Effect of lead nitrate on thyroid function of the Indian palm squirrel, Funambulus pennanti (Wroughton).

Some of the known toxic effects of lead in mammals including man are, impaired heme synthesis, anemia, nepatopathy, nephropathy, behavioral disorders and neuropathy. However, very little is known about the effect of lead on endocrine physiology. Some data are available on lead induced impairment of thyroid function in occupationally exposed men and experimental rats. As lead nitrate is largely consumed through water and food, in this study the wild rodents Funambulus pennanti were administered lead through their drinking water and their thyroid structure, radioiodine 131-I percentage uptake and protein bound iodine (PBI) level were assessed.

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

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.

Mammalian Pests of Cocoa in South India

Abstract The Western Ghats squirrel, Funambulus tristriatus Waterhouse; the South Indian palm squirrel, F. palmarum Linnaeus and the black rat, Rattus rattus Linnaeus were observed to be causing much damage to cocoa in South India; the palm civet, Paradoxurus hermaphroditus Pallas and the bonnet monkey, Macaca radiata Geoffroy were causing minor damage. Monthly surveys made for one year in Karnataka showed that the percentage of damage caused by rodents was 29.0; that by civets and monkeys 0.4 and 0.3 respectively. In Kerala and one district of Tamil Nadu rodents were estimated to be causing 15% damage and civets 3%; no monkey damage was found.

Laboratory evaluation of anticoagulant-treated baits for control of the northern palm squirrel, Funambulus pennanti Wroughton.

Individually caged northern palm squirrels, Funambulus pennanti, were fed with bait containing 0.025% warfarin or fumarin, 0.0075% chlorophacinone or 0.005% brodifacoum for a fixed number of days varying from 1 to 14. Brodifacoum (WBA 8119) was found most toxic since 66% and 70% of the animals died after one and two days' feeding respectively. Chlorophacinone killed 70% of the squirrels after three days' feeding. Squirrels were relatively tolerant to warfarin and fumarin since the mortality after a period of 14 days' feeding was only 58% and 75% respectively.

Laboratory evaluation of poison-base for the control ofFunambulus pennanti

Funambulus pennanti, the northern palm squirrel preferred wheat in its different forms out of ten cereals and oil seeds offered. It is revealed that the squirrels are selective feeders since out of eleven forms, i.e., whole, cracked, roasted and flour, wheat was found to be most palatable in seven trials followed by bajra (three trials) and jowar once. The addition of vegetable oils, salt and sugar does not enhance the bait acceptance. However, they preferred sugar in comparison to salt, and arachis and sesame oils. Wheat in its whole form is, therefore, recommended for use as a poison base for the control ofF. pennanti. In the absence of wheat, cracked bajra can also be used, which is the next preferred bait. The calorific requirement ofF. pennanti ranges from 16·18 to 34·98 k cal/100 g body weight/day when the bait is provided in single food choice.

Poison- and Bait-Shyness of Northern Palm Squirrel, Funambulas pennanti pennanti WROUGHTON

Poison- and Bait-Shyness of Northern Palm Squirrel, Funambulas pennanti pennanti WROUGHTON

Pneumocystis carinii infections in zoo animals.

Pneumocystis carinii was found to be present in the lungs of twenty-three zoo animals in the Netherlands. The following species were represented: red kangaroo, common tree shrew, Senegal-Galago, Demidoff's-Galago, brown howler monkey, woolly monkey, long-haired spider monkey, white-eared marmoset, chimpanzee, three-toed sloth, palm squirrel, red panda, fennec fox, tree hyrax and large-toothed hyrax.

Observations of centriole formation in male meiosis.

Centriole formation in male meiosis of the hyrax, Heterohyrax syriacus, and the Berdmore palm squirrel, Memetes berdmorei, was investigated by serial section analysis of selected regions of the seminiferous epithelium and isolated meiotic cells. Two periods of centriole formation were observed, a first in cells in transition between zygotene and pachytene and a second in the secondary spermatocytes. The duplication events before each meiotic division insured the presence of a centriolar duplex at each division pole. The parental member of each duplex of the second division was closely associated, at its distal end, with the plasma membrane. This orientation was established in the secondary spermatocyte and persisted until the completion of telophase II. Subsequently in early spermatids, each duplex assumed a characteristic orientation adjacent to the nucleus.

Reproductive cycle of the female five-striped Indian palm squirrel, Funambulus pennanti (Wroughton).

Summary. The five-striped Indian palm squirrel, Funambulus pennanti, is a seasonal breeder from January to August. Mature females are sexually quiescent from September to December; recrudescence of the gonad starts in late December. The palm squirrel is a reflex ovulator. A mature female may produce two litters of approximately three young each in one breeding season. The period of suckling is 6 weeks. Mature females experience a short period of post-lactational anoestrus during the breeding season prior to the onset of second oestrus. The role of exteroceptive factors in regulating the reproductive cycle of the palm squirrel is discussed.

Role of prolactin in the growth and secretory activity of the prostate and other accessory glands of mammals

Experimental evidence in support of the role of prolactin in the growth and secretory activity of the prostate and other accessory glands of mammals is reviewed. Special attention has been focused on the recent evidences based on the use of chemical indices of secretory activity of the prostate gland. The observed strain differences of the prostate in response to prolactin in rats and the paucity of data in other species is emphasized. The need for studies on mammals with compact prostate gland is stressed. Prolactin synergizes with androgen in stimulating fructose and citric acid secretion by the accessory glands in the Indian palm squirrel. In spite of our basic understanding of the synergistic effects of prolactin, its mechanism of action is still enigmatic. The importance of the use of organ culture techniques in the study of the effects of prolactin has been underscored.

The reproductive cycle of the male Indian palm squirrel, Funambulus pennanti Wroughton.

The reproductive cycle of the male Indian palm squirrel was investigated from a collection of 365 animals during the period May 1963 to May 1965. It breeds from January to the end of July. This is followed by a period of regression (August-September) and the animals are quiescent during October and November. Redevelopment of the reproductive organs is initiated in December and results in the restoration of reproductive activity in late January. Sexual maturity in squirrels is attained by 8 to 9 months of age. The histological changes in the testis, epididymis and vas deferens with age and breeding season are described. The weights of the prostate gland and seminal vesicles show changes that parallel testicular weights and interstitial cell morphology. However, there is a time lag in the response of accessory glands both during the transition from puberal to the adult condition and in adults during the change from recrudescence to breeding condition. The role of exteroceptive factors in regulating the reproductive cycle of the palm squirrel is discussed.