Thyrotropin-releasing hormone (TRH), a hypothalamic orally active neuropeptide, has been manifested in a wide range of biological responses. Besides its central role in regulating the pituitary-thyroid axis by simulating the release of thyrotropin, TRH has considerable influence on the activity of a number of neurobiological systems. Due to the therapeutic potential of TRH to treat several CNS maladies, the development of CNS-selective and metabolically stable TRH analogs is an area of interest. TRH is known to elicit its biological response through two G-protein coupled receptors for TRH (namely, TRH-R1 and TRH-R2). The distinct distribution of TRH receptors in tissues has provided opportunity to discover receptor subtype-specific analogs, which would demonstrate high CNS activities, and are completely free of hormonal activities. In this review, an in-depth analysis of the chemistry and biology of TRH and its analogs is provided. Recent discoveries of TRH-R2 selective analogs, TRH super agonists, metabolically stable TRH analogs, and targeted delivery of TRH analogs have been also discussed.
OBJECTIVE:The aim of the present study was to evaluate the solanesol (SNL)-mediated coenzyme-Q10 restoration to ameliorate 3-nitropropionic (3-NP)-induced behavioral, biochemical, and histological changes which resemble Huntington's disease (HD)-like symptoms in men.MATERIALS AND METHODS:Various behavioral and biochemical parameters were carried out to evaluate the activity of SNL on 3-NP-treated rats. To determine the therapeutic significance of SNL on HD, different behavioral tests such as memory task, locomotor activity, grip strength, and beam cross and some biochemical test along with histopathological findings were done.RESULTS:Chronic 3-NP, 10 mg/kg i.p., caused physical and mental abnormalities in animals, including memory impairment, weak grip strength, abnormal posture, and cognitive deficit. Biochemical analysis of brain homogenate in 3-NP-treated rats showed altered mitochondrial complexes, oxidative stress, and elevated lipid biomarkers. Neurohistological alterations of hippocampus, basal ganglia, and cerebral cortex of 3-NP-treated rats exhibit severe neuronal space, irregular damaged cells, and dense pyknotic nuclei-associated marked focal diffused gliosis. SNL administered for 15 days significantly improved motor performance and cognitive behavior task and restored the histopathological changes. Further, SNL treatment significantly improved mitochondrial complexes such as coenzyme-Q10 enzyme activity and attenuated inflammatory and oxidative damage of rat brain.CONCLUSION:In the present research work, SNL (5, 10, and 15 mg/kg p.o.) provided notable neuroprotective effect, which was confirmed by behavioral paradigms and biochemical test. It restored the behavioral and biochemical alteration caused by 3-NP and confirmed the strong neuroprotective mechanism of SNL in 3-NP-intoxicated memory and cognitive abnormalities.
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