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Singh O, Pradhan DR, Nagalakashmi B, Kumar S, Mitra S, Sagarkar S, Sakharkar AJ, Lechan RM, Singru PS. Thyrotropin-releasing hormone (TRH) in the brain and pituitary of the teleost, Clarias batrachus and its role in regulation of hypophysiotropic dopamine neurons. J Comp Neurol 2018; 527:1070-1101. [PMID: 30370602 DOI: 10.1002/cne.24570] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 10/18/2018] [Accepted: 10/23/2018] [Indexed: 11/11/2022]
Abstract
Thyrotropin-releasing hormone (TRH) regulates the hypothalamic-pituitary-thyroid axis in mammals and also regulates prolactin secretion, directly or indirectly via tuberoinfundibular dopamine neurons. Although TRH is abundantly expressed in teleost brain and believed to mediate neuronal communication, empirical evidence is lacking. We analyzed pro-TRH-mRNA expression, mapped TRH-immunoreactive elements in the brain and pituitary, and explored its role in regulation of hypophysiotropic dopamine (DA) neurons in the catfish, Clarias batrachus. Partial pro-TRH transcript from C. batrachus transcriptome showed six TRH progenitors repeats. Quantitative real-time polymerase chain reaction (qRT-PCR) identified pro-TRH transcript in a number of different brain regions and immunofluorescence showed TRH-immunoreactive cells/fibers in the olfactory bulb, telencephalon, preoptic area (POA), hypothalamus, midbrain, hindbrain, and spinal cord. In the pituitary, TRH-immunoreactive fibers were seen in the neurohypophysis, proximal pars distalis, and pars intermedia but not rostral pars distalis. In POA, distinct TRH-immunoreactive cells/fibers were seen in nucleus preopticus periventricularis anterior (NPPa) that demonstrated a significant increase in TRH-immunoreactivity when collected during preparatory and prespawning phases, reaching a peak in the spawning phase. Although tyrosine hydroxylase (TH)-immunoreactive neurons in NPPa are hypophysiotropic, none of the TRH-immunoreactive neurons in NPPa accumulated neuronal tracer DiI following implants into the pituitary. However, 87 ± 1.6% NPPa TH-immunoreactive neurons were surrounded by TRH-immunoreactive axons that were seen in close proximity to the somata. Superfused POA slices treated with TRH (0.5-2 μM) significantly reduced TH concentration in tissue homogenates and the percent TH-immunoreactive area in the NPPa. We suggest that TRH in the brain of C. batrachus regulates a range of physiological functions but in particular, serves as a potential regulator of hypophysiotropic DA neurons and reproduction.
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Affiliation(s)
- Omprakash Singh
- School of Biological Sciences, National Institute of Science Education and Research (NISER)-Bhubaneswar, Jatni, India.,Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, India
| | - Dipti R Pradhan
- School of Biological Sciences, National Institute of Science Education and Research (NISER)-Bhubaneswar, Jatni, India.,Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, India
| | - B Nagalakashmi
- Department of Biotechnology, Savitribai Phule Pune University, Pune, India
| | - Santosh Kumar
- School of Biological Sciences, National Institute of Science Education and Research (NISER)-Bhubaneswar, Jatni, India.,Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, India
| | - Saptarsi Mitra
- School of Biological Sciences, National Institute of Science Education and Research (NISER)-Bhubaneswar, Jatni, India.,Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, India
| | - Sneha Sagarkar
- Department of Biotechnology, Savitribai Phule Pune University, Pune, India
| | - Amul J Sakharkar
- Department of Biotechnology, Savitribai Phule Pune University, Pune, India
| | - Ronald M Lechan
- Division of Endocrinology, Diabetes and Metabolism, Department of Medicine, Tupper Research Institute, Tufts Medical Center, Boston, Massachusetts.,Department of Neuroscience, Tufts University School of Medicine, Boston, Massachusetts
| | - Praful S Singru
- School of Biological Sciences, National Institute of Science Education and Research (NISER)-Bhubaneswar, Jatni, India.,Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, India
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Wecht JM, Weir JP, Radulovic M, Bauman WA. Effects of midodrine and L-NAME on systemic and cerebral hemodynamics during cognitive activation in spinal cord injury and intact controls. Physiol Rep 2016; 4:4/3/e12683. [PMID: 26869679 PMCID: PMC4758920 DOI: 10.14814/phy2.12683] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
We previously showed that increases in mean arterial pressure (MAP) following administration of midodrine hydrochloride (MH) and nitro‐L‐arginine methyl ester (L‐NAME) resulted in increased mean cerebral blood flow velocity (MFV) during head‐up tilt in hypotensive individuals with spinal cord injury (SCI) and question if this same association was evident during cognitive activation. Herein, we report MAP and MFV during two serial subtraction tasks (SSt) given before (predrug) and after (postdrug) administration of MH; (10 mg), L‐NAME (1 mg/kg) or no drug (ND) in 15 subjects with SCI compared to nine able‐bodied (AB) controls. Three‐way factorial analysis of variance (ANOVA) models were used to determine significant main and interaction effects for group (SCI, AB), visit (MH, L‐NAME, ND), and time (predrug, postdrug) for MAP and MFV during the two SSt. The three‐way interaction was significant for MAP (F = 4.262; P = 0.020); both MH (30 ± 26 mmHg; P < 0.05) and L‐NAME (27 ± 22 mmHg; P < 0.01) significantly increased MAP in the SCI group, but not in the AB group. There was a significant visit by time interaction for MFV suggesting an increase from predrug to postdrug following L‐NAME (6 ± 8 cm/sec; P < 0.05) and MH (4 ± 7 cm/sec; P < 0.05), regardless of study group, with little change following ND (3 ± 3 cm/sec). The relationship between change in MAP and MFV was significant in the SCI group following administration of MH (r2 = 0.38; P < 0.05) and L‐NAME (r2 = 0.32; P < 0.05). These antihypotensive agents, at the doses tested, raised MAP, which was associated with an increase MFV during cognitive activation in hypotensive subjects with SCI.
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Affiliation(s)
- Jill M Wecht
- VA RR&D National Center for the Medical Consequences of Spinal Cord Injury, James J. Peters VAMC, Bronx, New York The Medical Service, James J. Peters VAMC, Bronx New York Department of Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York Department of Rehabilitation Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York
| | - Joseph P Weir
- Department of Health, Sport and Exercise Sciences, The University of Kansas, Lawrence, Kansas
| | - Miroslav Radulovic
- VA RR&D National Center for the Medical Consequences of Spinal Cord Injury, James J. Peters VAMC, Bronx, New York The Medical Service, James J. Peters VAMC, Bronx New York Department of Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York Department of Rehabilitation Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York
| | - William A Bauman
- VA RR&D National Center for the Medical Consequences of Spinal Cord Injury, James J. Peters VAMC, Bronx, New York The Medical Service, James J. Peters VAMC, Bronx New York Department of Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York Department of Rehabilitation Medicine, The Icahn School of Medicine at Mount Sinai, New York, New York
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