Hypothyroidism is a common disorder that is associated with psychological disturbances such as dementia, depression, and psychomotor disorders. We recently found that chronic treatment with the T-type calcium channel enhancer SAK3 prevents the cholinergic neurodegeneration induced by a single intraperitoneal (i.p.) injection of methimazole (MMI; 75 mg/kg), thereby improving cognition. Here, we evaluated the acute effect of SAK3 on cognitive impairments and its mechanism of action following the induction of hypothyroidism. Hypothyroidism was induced by 2 injections of MMI (75 mg/kg, i.p.) administered once per week. Four weeks after the final MMI treatment, MMI-treated mice showed reduced serum thyroxine (T4) levels and cognitive impairments without depression-like behaviors. Although acute SAK3 (1.0 mg/kg, p.o.) administration failed to ameliorate the decreased T4 levels and histochemical destruction of the glomerular structure, acute SAK3 (1.0 mg/kg, p.o.) administration significantly reduced cognitive impairments in MMI-treated mice. Importantly, the α7 nicotinic acetylcholine receptor (nAChR)-selective inhibitor methyllycaconitine (MLA; 12 mg/kg, i.p.) and T-type calcium channel-specific blocker NNC 55–0396 (25 mg/kg, i.p.) antagonized the acute effect of SAK3 on memory deficits in MMI-treated mice. We also confirmed that acute SAK3 administration does not rescue reduced olfactory marker protein or choline acetyltransferase immunoreactivity levels in the olfactory bulb or medial septum. Taken together, these results suggest that SAK3 has the ability to improve the cognitive decline caused by hypothyroidism directly through activation of nAChR signaling and T-type calcium channels.

Bernal J: Thyroid hormones and brain development. Vitam Horm 2005; 71: 95–122.
Dugbartey AT: Neurocognitive aspects of hypothyroidism. Arch Intern Med 1998; 158: 1413–1418.
Fernandez-Lamo I, Montero-Pedrazuela A, Delgado-Garcia JM, Guadano-Ferraz A, Gruart A: Effects of thyroid hormone replacement on associative learning and hippocampal synaptic plasticity in adult hypothyroid rats. Eur J Neurosci 2009; 30: 679–692.
Breteler MM, van Duijn CM, Chandra V, Fratiglioni L, Graves AB, Heyman A: Medical history and the risk of Alzheimer’s disease: a collaborative re-analysis of case-control studies. Int J Epidemiol 1991; 20(suppl 2):S36–S42.
Ganguli M, Burmeister LA, Seaberg EC, Belle S, DeKosky ST: Association between dementia and elevated TSH: a community-based study. Biol Psychiatry 1996; 40: 714–725
van Osch LA, Hogervorst E, Combrinck M, Smith AD: Low thyroid-stimulating hormone as an independent risk factor for Alzheimer disease. Neurology 2004; 62: 1967–1971.
Tan ZS, Beiser A, Vasan RS, Au R, Auerbach S, Kiel DP, Wolf PA, Seshadri S: Thyroid function and the risk of Alzheimer disease: the Framingham study. Arch Intern Med 2008; 168: 1514–1520.
Cooper DS, Bode HH, Nath B, Saxe V, Maloof F, Ridgway: Methimazole pharmacology in man: studies using a newly developed radioimmunoassay for methimazole. J Clin Endocrinol Metab 1984; 58: 473–479.
Desouza LA, Ladiwala U, Daniel SM, Agashe S, Vaidya RA, Vaidya VA: Thyroid hormone regulates hippocampal neurogenesis in the adult rat brain. Mol Cell Neurosci 2005; 29: 414–426.
Hosseini M, Dastghaib SS, Rafatpanah H, Hadjzadeh MA, Nahrevanian H, Farrokhi I: Nitric oxide contributes to learning and memory deficits observed in hypothyroid rats during neonatal and juvenile growth. Clinics (Sao Paulo) 2010; 65: 1175–1181.
Bergman U, Brittebo EB: Methimazole toxicity in rodents: covalent binding in the olfactory mucosa and detection of glial fibrillary acidic protein in the olfactory bulb. Toxicol Appl Pharmacol 1999; 155: 190–200.
Blanco-Hernandez E, Valle-Leija P, Zomosa-Signoret V, Drucker-Colin R, Vidaltamayo R: Odor memory stability after reinnervation of the olfactory bulb. PLos One 2012; 7:e46338.
HanF, Shioda N, Moriguchi S, Qin ZH, Fukunaga K: The vanadium (IV) compound rescues septohippocampal cholinergic neurons from neurodegeneration in olfactory bulbectomized mice. Neuroscience 2008; 151: 671–679.
Noreen H, Yabuki Y, Fukunaga K: Novel spiroimidazopyridine derivative SAK3 improves methimazole-induced cognitive deficits in mice. Neurochem Int 2017; 108: 91–99.
Kojima M, Kim JS, Uchimurea H, Hirano M, Nakahara T, Matsumoto T: Effect of thyroidectomy on choline acetyltransferase in rat hypothalamic nuclei. Brain Res 1981; 209: 227–230.
Oh JD, Butcher LL, Woolf NJ: Thyroid hormone modulates the development of cholinergic terminal fields in the rat forebrain: relation to nerve growth factor receptor. Brain Res Dev Brain Res 1991; 59: 133–142.
Sawin S, Brodish P, Carter CS, Stanton ME, Lau C: Development of cholinergic neurons in rat brain regions: dose-dependent effects of propylthiouracil-induced hypothyroidism. Neurotoxicol Teratol 1998; 20: 627–635.
Moriguchi S, Yamamoto Y, Ikuno T, Fukunaga K: Sigma-1 receptor stimulation by dehydroepiandrosterone ameliorates cognitive impairment through activation of CaM kinase II, protein kinase C and extracellular signal-regulated kinase in olfactory bulbectomized mice. J Neurochem 2011; 117: 879–891.
Yamamoto Y, Shioda N, Han F, Moriguchi S, Fukunaga K: Novel cognitive enhancer ST101 enhances acetylcholine release in mouse dorsal hippocampus through T-type voltage-gated calcium channel stimulation. J Pharmacol Sci 2013; 121: 212–226.
Yabuki Y, Matsuo K, Izumi H, Haga H, Yoshida T, Wakamori M, Kakei A, Sakimura K, Fukuda T, Fukunaga K: Pharmacological properties of SAK3, a novel T-type voltage-gated Ca2+ channel enhancer. Neuropharmacology 2017; 117: 1–13.
Yabuki Y, Jing X, Fukunaga K: The T-type calcium channel enhancer SAK3 inhibits neuronal death following transient brain ischemia via nicotinic acetylcholine receptor stimulation. Neurochem Int 2017; 108: 1–10.
Abe T, Kakehi A, Suga H, Okumura Y, Itoh K: Synthesis of spiro[2-cyclopentene-1, 3’-imidazo[1, 2a ]pyridine] derivatives and their interesting behavior in 1H-NMR spectra in deuteriochloroform. Heterocycles 2010; 81: 2075–2086.
Yabuki Y, Fukunaga K: Oral administration of glutathione improves memory deficits following transient brain ischemia by reducing brain oxidative stress. Neuroscience 2013; 250: 394–407.
Strekalova T, Spanagel R, Bartsch D, Henn FA, Gass P: Stress-induced anhedonia in mice is associated with deficits in forced swimming and exploration. Neuropsychopharmacology 2004; 29: 2007–2017.
Steru L, Chermat R, Thierry B, Simon P: The tail suspension test: a new method for screening antidepressants in mice. Psychopharmacology (Berl) 1985; 85: 367–370.
Shioda N, Beppu H, Fukuda T, Li E, Kitajima I, Fukunaga K: Aberrant calcium/calmodulin-dependent protein kinase II (CaMKII) activity is associated with abnormal dendritic spine morphology in the ATRX mutant mouse brain. J Neurosci 2011; 31: 346–358.
Yabuki Y, Shinoda Y, Izumi H, Ikuno T, Shioda N, Fukunaga K: Dehydroepiandrosterone administration improves memory deficits following transient brain ischemia through sigma-1 receptor stimulation. Brain Res 2015; 1622: 102–113.
Fukunaga K, Goto S, Miyamoto E: Immunohistochemical localization of Ca2+/calmodulin-dependent protein kinase II in rat brain and various tissues. J Neurochem 1988; 51: 1070–1078.
Xie F, Zhou X, Genter MB, Behr M, Gu J, Ding X: The tissue-specific toxicity of methimazole in the mouse olfactory mucosa is partly mediated through target-tissue metabolic activation by CYP2A5. Drug Metab Dispos 2011; 39: 947–951.
Ogawa T, Takezawa K, Shimizu S, Shimizu T: Valproic acid promotes neural regeneration of olfactory epithelium in adult mice after methimazole-induced damage. Am J Rhinol Allergy 2014; 28: 95–99.
Dias GR, Vieira FA, Dobrachinski F, Bridi JC, Balk Rde S, Soares FA, Nogueira CW, Barbosa NB: Diphenyl diselenide diet intake improves spatial learning and memory deficits in hypothyroid female rats. Int J Dev Neurosc 2012; 30: 83–89.
Krishnan V, Nestler EJ: Animal models of depression: molecular perspectives. Curr Top Behav Neurosci 2011; 7: 121–147.
Overstreet DH: Modeling depression in animal models. Methods Mol Biol 2012; 829: 125–144.
American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders. DSM-V. Washington, American Psychiatric Association, 2013.
Margolis FL: A brain protein unique to the olfactory bulb. Proc Natl Acad Sci U S A 1972; 69: 1221–1224.
Lee AC, He J, Ma M: Olfactory marker protein is critical for functional maturation of olfactory sensory neurons and development of mother preference. J Neurosci 2011; 31: 2974–2982.
Xie F, Zhou X, Genter MB, Behr M, Gu J, Ding X: The tissue-specific toxicity of methimazole in the mouse olfactory mucosa is partly mediated through target-tissue metabolic activation by CYP2A5. Drug Metab Dispos 2011; 39: 947–951.
Uranagase A, Katsunuma S, Doi K, Nibu K: BDNF expression in olfactory bulb and epithelium during regeneration of olfactory epithelium. Neurosci Lett 2012; 516: 45–49.
Brittebo EB: Metabolism-dependent toxicity of methimazole in the olfactory nasal mucosa. Pharmacol Toxicol 1995; 76: 76–79.
Lisman J, Schulman H, Cline H: The molecular basis of CaMKII function in synaptic and behavioural memory. Nat Rev Neurosci 2002; 3: 175–190.
Sherrin T, Blank T, Todorovic C: c-Jun N-terminal kinases in memory and synaptic plasticity. Rev Neurosci 2011; 22: 403–410.
Giese KP: Long-term potentiation and memory; in Giese KP (ed): Memory Mechanisms in Health and Disease. Singapore, World Scientific Publishing, 2012, pp 1–7.
Alzoubi KH, Gerges NZ, Alkadhi KA: Levothyroxin restores hypothyroidism-induced impairment of LTP of hippocampal CA1: electrophysiological and molecular studies. Exp Neurol 2005; 195: 330–341.
Usenko VS, Lepekhin EA, Lyzogubov VV, Kornilovska IN, Apostolov EO, Tytarenko RG, Witt M: The influence of maternal hypothyroidism and radioactive iodine on rat embryonal development: thyroid C-cells. Anat Rec 1999; 256: 7–13.
Cano-Europa E, Blas-Valdivia V, Franco-Colin M, Gallardo-Casas CA, Ortiz-Butron R: Methimazole-induced hypothyroidism causes cellular damage in the spleen, heart, liver, lung and kidney. Acta Histochem 2011; 113: 1–5.
Safayee S, Karbalaei N, Noorafshan A, Nadimi E: Induction of oxidative stress, suppression of glucose-induced insulin release, ATP production, glucokinase activity, and histomorphometric changes in pancreatic islets of hypothyroid rat. Eur J Pharmacol 2016; 791: 147–156.
Demet MM, Ozmen B, Deveci A, Boyvada S, Adigüzel H, Aydemir O: Depression and anxiety in hyperthyroidism. Arch Med Res 2002; 33: 552–556.
Chaalal A, Poirier R, Blum D, Gillet B, Le Blanc P, Basquin M, Buee L, Laroche S, Enderlin V: PTU-induced hypothyroidism in rats leads to several early Neuropathological signs of Alzheimer's disease in the -hippocampus and spatial memory -impairments. Hippocampus 2014; 24: 1381–1393.
Bernal J, Guadano-Ferraz A, Morte B: Thyroid hormones transporters-functions and clinical implications. Nat Rev Endocrinol 2015; 11: 406–417.
Genter MB, Deamer NJ, Blake BL, Wesley DS, Levi PE: Olfactory toxicity of methimazole: dose-response and structure-activity studies and characterization of flavin-containing monooxygenase activity in the Long-Evans rat olfactory mucosa. Toxicol Pathol 1995: 23: 477–486.
Mizutani T, Yoshida K, Murakami M, Shirai M, Kawazoe S: Evidence for the involvement of N-methylthiourea, a ring cleavage metabolite, in the hepatotoxicity of methimazole in glutathione-depleted mice: structure-toxicity and metabolic studies. Chem Res Toxicol 2000; 13: 170–176.
Bergman U, Östergren A, Gustafson AL, Brittebo B: Differential effects of olfactory toxicants on olfactory regeneration. Arch Toxicol 2002: 76: 104–112.
Sieck MH, Gordon B: Selective olfactory bulb lesions: reactivity changes and avoidance learning in rats. Physiol Behav 1972; 9: 545–552.
Koss E: Olfactory dysfunction in Alzheimer disease. Dev Neuropsychol 1986; 2: 89–91.
Esiri MM, Wilcock GK: The olfactory bulbs in Alzheimer’s disease. J Neurol Neurosurg Psychiatry 1984; 47: 56–60.
Senut MC, Menetrey D, Lamour Y: Cholinergic and peptidergic projections from the medial septum and the nucleus of the diagonal band of Broca to dorsal hippocampus, cingulate cortex and olfactory bulb: a combined wheatgerm agglutinin-apohorseradish peroxidase-gold immunohistochemical study. Neuroscience 1989; 30: 385–403.
Bobkova NV, Nesterova IV, Nesterov VV: The state of cholinergic structures in forebrain of bulbectomized mice. Bull Exp Biol Med 2001; 131: 427–431.
Machado DG, Cunha MP, Neis VB, Balen GO, Colla A, Grando J, Brocardo PS, Bettio LE, Capra JC, Rodrigues AL: Fluoxetine reverses depressive-like behaviors and increases hippocampal acetylcholinesterase activity induced by olfactory bulbectomy. Pharmacol Biochem Behav 2012; 103: 220–229.
Yamamoto Y, Fukunaga K: Donepezil rescues the medial septum cholinergic neurons via nicotinic ACh receptor stimulation in olfactory bulbectomized mice. Adv Alzheimer Dis 2013; 2: 161–170.
Talley EM, Cribbs LL, Lee JH, Daud A, Perez-Reyes E, Bayliss DA: Differential distribution of three members of a gene family encoding low voltage-activated (T-type) calcium channels. J Neurosci 1999; 19: 1895–1911.
Nevian T, Sakmann B: Spine Ca2+ signaling in spike-timing-dependent plasticity. J Neurosci 2006; 26: 11001–11013.
Schmidt-Hieber C, Jonas P, Bischofberger J: Enhanced synaptic plasticity in newly generated granule cells of the adult hippocampus. Nature 2004; 429: 184–187.
Lee S, Ahmed T, Lee s, Kim H, Choi S, Kim DS, Kim SJ, Cho J, Shin HS: Bidirectional modulation of fear extinction by mediodorsal thalamic firing in mice. Nat Neurosci 2011; 15: 302–314.
Kawai H, Lazar R, Metherate R: Nicotinic control of axon excitability regulates thalamocortical transmission. Nat Neurosci 2007; 10: 1168–1175.
Pieschl RL, Miller R, Jones KM, Post-Munson DJ, Chen P, Newberry K, Benitex Y, Molski T, Morgan D, McDonald IM, Macor JE, Olson RE, Asaka Y, Digavalli S, Easton A, Herrington J, Westphal RS, Lodge NJ, Zaczek R, Bristow LJ, Li YW: Effects of BMS-902483, an α7 nicotinic acetylcholine receptor partial agonist, on cognition and sensory gating in relation to receptor occupancy in rodents. Eur J Pharmacol 2017; 807: 1–11.
Young JW, Crawford N, Kelly JS, Kerr LE, Marston HM, Spratt C: Impaired attention is central to the cognitive deficits observed in alpha 7 deficient mice. Eur Neuropsychopharmacol 2007; 17: 145–155.
Adams JP, Sweatt JD: Molecular psychology: roles for the ERK MAP kinase cascade in memory. Annu Rev Pharmacol Toxicol 2002; 42: 135–163.
Tsien RW, Tsien RY: Calcium channels, stores, and oscillations. Annu Rev Cell Biol 1990; 6: 715–760.
Szabo SI, Zelles T, Lendvai B: Intracellular Ca2+ dynamics of hippocampal interneurons following nicotinic acetylcholine receptor activation. Neurochem Int 2008; 52: 135–141.
Copyright / Drug Dosage / Disclaimer
Copyright: All rights reserved. No part of this publication may be translated into other languages, reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying, recording, microcopying, or by any information storage and retrieval system, without permission in writing from the publisher.
Drug Dosage: The authors and the publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accord with current recommendations and practice at the time of publication. However, in view of ongoing research, changes in government regulations, and the constant flow of information relating to drug therapy and drug reactions, the reader is urged to check the package insert for each drug for any changes in indications and dosage and for added warnings and precautions. This is particularly important when the recommended agent is a new and/or infrequently employed drug.
Disclaimer: The statements, opinions and data contained in this publication are solely those of the individual authors and contributors and not of the publishers and the editor(s). The appearance of advertisements or/and product references in the publication is not a warranty, endorsement, or approval of the products or services advertised or of their effectiveness, quality or safety. The publisher and the editor(s) disclaim responsibility for any injury to persons or property resulting from any ideas, methods, instructions or products referred to in the content or advertisements.
You do not currently have access to this content.