SAT-545 The Response of the Hypothalamic-Pituitary-Thyroid (HPT) Axis to a Palatable Diet or Exercise Depends on Sex and Housing Conditions in Adult Rats

Fasting down-regulates the hypothalamus-pituitary-thyroid (HPT) axis activity through a reduction of TRH synthesis in neurons of the parvocellular paraventricular nucleus of the hypothalamus (PVN). These TRH neurons project to the median eminence (ME), where TRH terminals are close to the cytoplasmic extensions of β2 tanycytes. Tanycytes express pyroglutamyl peptidase II (PPII), the TRH-degrading ectoenzyme that controls the amount of TRH that reaches the anterior pituitary. We tested the hypothesis that regulation of ME PPII activity is another mechanism by which fasting affects the activity of the HPT axis. Semiquantitative in situ hybridization histochemistry data indicated that PPII and deiodinase 2 mRNA levels increased in tanycytes after 48 hours of fasting. This increase was transitory, followed by an increase of PPII activity in the ME, and a partial reversion of the reduction in PVN pro-TRH mRNA levels and the number of TRH neurons detected by immunohistochemistry. In fed animals, adrenalectomy and corticosterone treatment did not change ME PPII activity 72 hours later. Methimazole-induced hypothyroidism produced a profound drop in tanycytes PPII mRNA levels, which was reverted by 3 days of treatment with T4. The activity of thyroliberinase, the serum isoform of PPII, was increased at most fasting time points studied. We conclude that delayed increases in both the ME PPII as well as the thyroliberinase activities in fasted male rats may facilitate the maintenance of the deep down-regulation of the HPT axis function, despite a partial reactivation of TRH expression in the PVN.

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Prepuberal light phase feeding induces neuroendocrine alterations in adult rats

Journal of Endocrinology ◽

10.1530/joe-16-0402 ◽

2017 ◽

Vol 232 (1) ◽

pp. 15-28 ◽

Cited By ~ 4

Author(s):

C García-Luna ◽

P Soberanes-Chávez ◽

P de Gortari

Keyword(s):

Body Weight ◽

Mrna Expression ◽

Hpa Axis ◽

Energy Homeostasis ◽

Body Weight Gain ◽

Serum Levels ◽

Leptin Resistance ◽

Positive Energy ◽

Adult Rats ◽

Hpt Axis

Feeding patterns are important factors in obesity evolvement. Time-restricted feeding schedules (tRF) during resting phase change energy homeostasis regulation, disrupting the circadian release of metabolism-regulating hormones, such as leptin, insulin and corticosterone and promoting body weight gain. Thyroid (HPT) and adrenal (HPA) axes exhibit a circadian regulation and are involved in energy expenditure, thus studying their parameters in tRF paradigms will elucidate their role in energy homeostasis impairments under such conditions. As tRF in young animals is poorly studied, we subjected prepuberal rats to a tRF either in light (LPF) or in darkness phase (DPF) and analyzed HPT and HPA response when they reach adulthood, as well as their arcuate (ARC) and paraventricular (PVN) hypothalamic nuclei neurons’ sensitivity to leptin in subsets of 10-week-old animals after fasting and with i.p. leptin treatment. LPF group showed high body weight and food intake, along with increased visceral fat pads, corticosterone, leptin and insulin serum levels, whereas circulating T4 decreased. HPA axis hyperactivity was demonstrated by their high PVN Crf mRNA expression; the blunted activity of HPT axis, by the decreased hypophysiotropic PVN Trh mRNA expression. Trh impaired expression to the positive energy balance in LPF, accounted for their ARC leptin resistance, evinced by an increased Npy and Socs3 mRNA expression. We concluded that the hyperphagia of prepuberal LPF animals could account for the HPA axis hyperactivity and for the HPT blocked function due to the altered ARC leptin signaling and impaired NPY regulation on PVN TRH neurons.

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Size constraints of telemeters in rats

Journal of Applied Physiology ◽

10.1152/jappl.1998.85.4.1564 ◽

1998 ◽

Vol 85 (4) ◽

pp. 1564-1571 ◽

Cited By ~ 12

Author(s):

M. M. Moran ◽

R. R. Roy ◽

C. E. Wade ◽

B. J. Corbin ◽

R. E. Grindeland

Keyword(s):

Phase 1 ◽

Maximum Size ◽

Skin Lesions ◽

Activity Levels ◽

Housing Conditions ◽

Daily Cycle ◽

Adult Rats ◽

Lower Growth ◽

Size Constraints

This study was designed to determine the maximum-size subcutaneous telemeter that would enable long-term and multichannel data collection in a 170-g rat for 90 days. In phase 1, rats with implants weighing 5 (2.5 cm3), 15 (7.5 cm3), 25 (12.5 cm3), 35 (17.5 cm3), or 45 (22.5 cm3) g were compared with sham-operated (SOC) and nonoperated (NOC) control animals. Severe skin lesions, seromas, and lower growth rates were observed in rats having implants ≥35 g. Thus, in phase 2, rats implanted with 23.5 g (17.5 cm3; 11-g active telemeter and 12.5-g implant) were compared with rats implanted with 11 g (6 cm3; telemeter only) and with the SOC and NOC groups. No differences were found among implanted groups in mean arterial pressure (MAP), heart rate (HR), subcutaneous temperature, or spontaneous activity under standard housing conditions. All groups were more active and had a higher MAP during the dark than the light phase of the daily cycle. During 2 h of cold exposure (3°C), both telemetered groups exhibited similar changes in HR, MAP, temperature, and activity levels. Adrenal glands were larger in the 23.5-g group (51 ± 1.6 mg) than in the SOC (46 ± 1.0 mg) and the NOC groups (41 ± 2.0 mg). No other significant differences were found in organ, muscle, or bone weights. These data verify the feasibility of using 23.5-g (17.5 cm3) subcutaneous telemeters for chronic recordings in young adult rats.

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Delayed onset of puberty in male offspring from bisphenol A-treated dams is followed by the modulation of gene expression in the hypothalamic–pituitary–testis axis in adulthood

Reproduction Fertility and Development ◽

10.1071/rd17107 ◽

2017 ◽

Vol 29 (12) ◽

pp. 2496 ◽

Cited By ~ 10

Author(s):

Isabela M. Oliveira ◽

Renata M. Romano ◽

Patricia de Campos ◽

Monica D. Cavallin ◽

Claudio A. Oliveira ◽

...

Keyword(s):

Estrogen Receptor ◽

Bisphenol A ◽

Mrna Expression ◽

Sexual Differentiation ◽

Later Life ◽

World Health ◽

Control Group ◽

Adult Rats ◽

Endocrine Disrupting Chemical ◽

Hpt Axis

Bisphenol A (BPA) is a synthetic endocrine-disrupting chemical of high prevalence in the environment, which may affect the function of the hypothalamic–pituitary–testis (HPT) axis in adult rats. The aim of the present study was to evaluate whether exposure to BPA during hypothalamic sexual differentiation at doses below the reproductive no observable adverse effect level of the World Health Organization causes changes in the regulation of the HPT axis. For this, 0.5 or 5 mg kg−1 BPA was injected subcutaneously to the mothers from gestational day 18 to postnatal day (PND) 5. In adulthood (PND90), the mRNA expression of genes related to HPT axis was evaluated in hypothalamus, pituitary and testis. Hypothalamic expression of gonadotrophin-releasing hormone (Gnrh) and estrogen receptor 2 (Esr2) mRNA was increased in both BPA-treated groups compared to control group. In the pituitary, follicle stimulating hormone beta subunit (Fshb) and androgen receptor (Ar) mRNA expression was increased compared to control group in rats treated with 0.5 mg kg−1 of BPA, whereas estrogen receptor 1 (Esr1) mRNA expression was only increased in the group treated with 5 mg kg−1 of BPA, compared to control group. In the testis, there was increased expression of FSH receptor (Fshr) and inhibin beta B subunit (Inhbb) transcripts only in rats treated with 0.5 mg kg−1 of BPA. Serum testosterone and LH concentrations were increased in the group treated with 5 mg kg−1 of BPA. The results of the present study demonstrate for the first time that perinatal exposure to low doses of BPA during the critical period of hypothalamic sexual differentiation modifies the activity of the HPT axis in the offspring, with consequences for later life in adult rats.

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Further Studies on the Ultrastructure of Harderian Gland in Adult Rats

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100051451 ◽

1974 ◽

Vol 32 ◽

pp. 288-289

Author(s):

Alfredo Feria-Velasco ◽

Guadalupe Tapia-Arizmendi

Keyword(s):

Fine Structure ◽

Domestic Fowl ◽

Animal Species ◽

Acinar Cells ◽

Harderian Gland ◽

Myoepithelial Cells ◽

The Other ◽

Albino Rats ◽

Adult Rats ◽

Cell Components

The fine structure of the Harderian gland has been described in some animal species (hamster, rabbit, mouse, domestic fowl and albino rats). There are only two reports in the literature dealing on the ultrastructure of rat Harderian gland in adult animals. In one of them the author describes the myoepithelial cells in methacrylate-embbeded tissue, and the other deals with the maturation of the acinar cells and the formation of the secretory droplets. The aim of the present work is to analize the relationships among the acinar cell components and to describe the two types of cells located at the perifery of the acini.

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Biodegradable polyester neuroprostheses promote the reconnection of separated peripheral nerve stubs

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100130109 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1094-1095

Author(s):

Beverly L. Giammara ◽

Jennifer S. Stevenson ◽

Peggy E. Yates ◽

Robert H. Gunderson ◽

Jacob S. Hanker

Keyword(s):

Image Analysis ◽

Basement Membrane ◽

Periodic Acid ◽

Light And Electron Microscopy ◽

Computer Assisted ◽

Type Iii Collagen ◽

Image Analysis System ◽

Biodegradable Polyester ◽

Adult Rats ◽

Type Iv

An 11mm length of sciatic nerve was removed from 10 anesthetized adult rats and replaced by a biodegradable polyester Vicryl™ mesh sleeve which was then injected with the basement membrane gel, Matrigel™. It was noted that leg sensation and movement were much improved after 30 to 45 days and upon sacrifice nerve reconnection was noted in all animals. Epoxy sections of the repaired nerves were compared with those of the excised segments by the use of a variation of the PAS reaction, the PATS reaction, developed in our laboratories for light and electron microscopy. This microwave-accelerated technique employs periodic acid, thiocarbohydrazide and silver methenamine. It stains basement membrane or Type IV collagen brown and type III collagen (reticulin), axons, Schwann cells, endoneurium and perineurium black. Epoxy sections of repaired and excised nerves were also compared by toluidine blue (tb) staining. Comparison of the sections of control and repaired nerves was done by computer-assisted microscopic image analysis using an Olympus CUE-2 Image Analysis System.

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High-voltage EM description of the types and distribution of sensory endings in the inner conical body of the rat vibrissal follicle-sinus complex

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010015959x ◽

1990 ◽

Vol 48 (3) ◽

pp. 410-411

Author(s):

Tony M. Mosconi ◽

Min J. Song ◽

Frank L. Rice

Keyword(s):

Mammalian Species ◽

Dorsal Side ◽

Hair Shaft ◽

Sensory Innervation ◽

Conical Body ◽

Adult Rats ◽

Perpendicular Plane ◽

Ultrastructural Studies ◽

Unmyelinated Axons ◽

Sensory Endings

Whiskers or vibrissal follicle-sinus complexes (F-SCs) on the snouts of many mammalian species are structures that have complex, dense sensory innervation. The innervation of F-SCs is remarkably similar in all species with the exception of one site - the inner conical body (ICB). The ICB is an elongated cylindrical structure that encircles the hair shaft near the neck of the follicle. This site has received only cursory attention in ultrastructural studies of the F-SCAdult rats were perfused after the method of Renehan and Munger2. F-SCs were quartered longitudinally and embedded separately in Epon-Araldite. Serial 0.25 μm sections were cut in either the longitudinal or perpendicular plane through the ICB and examined with an AEI EM7 1.2 MV HVEM (Albany, NY) at 1000 KV. Sensory endings were reconstructed from serial micrographs through at least 20 μm in the longitudinal plane and through 10 μm in the perpendicular plane.From two to six small superficial vibrissal nerves converge upon the neck of the F-SC and descend into the ICB. The nerves branch into smaller bundles of myelinated and unmyelinated axons along the dorsal side of the hair shaft.

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