K Nagai et al Autonomic Neuroscience:Basic and Clinical 185 (2014)29-35 33 RSNA and BP(Tanida et al,2006),3)intracranial administration of di- olfactory stimulation with GFO and LVO scents.Consequently,the fol- phenhydramine eliminated the suppressing actions of either GFO or lowing results were observed:1)bilateral lesions of the SCN abolished R-(+)-limonene on GVNA(Tanida et al.,2005b),and 4)intracranial in- changes in the plasma glycerol concentration induced by olfactory stim- jection of thioperamide abolished the enhancing actions of either LVO ulation with either GFO or LVO scents in rats (Shen et al.,2007),2)bilat- or ()-linalool on GVNA (Tanida et al,2006). eral lesions of the SCN eliminated the changes in RSNA,BP and GVNA These findings suggest the following things:1)the histamine H1 re- elicited by olfactory stimulation with either GFO or LVO scents in rats ceptor is implicated in the mechanisms underlying the GFO-mediated (Tanida et al.,2005b,2006).and 3)bilateral lesions of the SCN abolished increase in RSNA and BP.2)the histamine H3 receptor is involved in the changes in BAT-SNA and BT caused by olfactory stimulation with ei- the mechanisms underlying LVO-mediated decrease in RSNA and ther GFO or LVO scents in rats(Tanida et al,2008b). BP,3).the histamine H1 receptor in the mechanisms underlying the These findings suggest that the SCN is implicated in the changes in GFO-mediated decrease in GVNA,and 4)the histamine H3 receptor in autonomic neurotransmission and physiological phenomena that the mechanisms underlying the LVO-mediated increase in GVNA. were caused by olfactory stimulation with either GFO or LVO scents. These findings suggest that olfactory stimulation with the GFO scent The findings described above implicate the SCN in the changes in au- increases BP and decreases appetite through the histamine H1 receptor tonomic neurotransmission and body functions induced by olfactory via the elevation in RSNA and the reduction in GVNA and other efferent stimulation with GFO and LVO scents.However,when electrolytic le- vagal nerves innervating the gut,and that olfactory stimulation with the sions of the SCN are made,the neural fibers pass through the lesioned LVO scent lowers BP and increases appetite through the histamine H3 area are also cut,and this denervation might be responsible for the dis- receptor via the suppression in RSNA and stimulation of GVNA and appearances of the autonomic and physiological responses to GFO and other efferent vagal nerves innervating the gut. LVO.In consideration of this possibility,we tried to examine the changes in autonomic neurotransmission and physiological phenomena that 5.Roles of circadian clock mechanism in changes in autonomic were due to olfactory stimulation with GFO and LVO scents in mice lack- neurotransmission and physiological phenomena due to GFO and LVO ing the ability to form circadian rhythms due to genetic manipulation. We used gene-knockout(KO)mice including the chryptochrome 1 In mammals,the hypothalamic suprachiasmatic nucleus(SCN)func- (Cry1)and chryptochrome 2(Cry2)double KO mice and Clock-mutant tions as a master circadian clock that forms circadian rhythms in phys- mice,which have no electrolytic brain lesions.Before starting this iological phenomena and behaviors (Lowrey and Takahashi,2004).The study,the authors confirmed the changes in the autonomic neurotrans- authors observed that the hyperglycemia induced by the intracranial mission and BP induced by olfactory stimulation with GFO and LVO administration of 2DG,an inhibitor of glucose utilization,is associated scents in intact control mice and obtained changes that were similar with the excitation of the sympathetic nerves innervating the pancreas. to those found in rats (Tanida et al.,2007a).That is,in urethane- liver and adrenal glands,a reduction in the blood insulin level and ele- anesthetized mice,olfactory stimulation with the GFO scent enhanced vations in the blood glucagon and adrenaline levels in rats (Nagai the activities of the sympathetic nerves innervating the adrenal glands et al.,1996a).Because a daily rhythm was observed in the hyperglyce- (ASNA).kidney (RSNA)and brown adipose tissue(BAT-SNA)and sup- mia induced by 2DG (Nagai et al.,1982),the effects of bilateral electro- pressed GVNA,and olfactory stimulation with the LVO scent reduced lytic lesions of the SCN on the 2DG-hyperglycemia were examined. ASNA,RSNA and BAT-SNA and increased GVNA (Tanida et al.,2007a). Consequently,it was found that SCN lesions eliminated the hyperglyce- Olfactory stimulation with GFO and LVO scents increased and lowered mia (Yamamoto et al.,1984;Nagai et al.,1996a),autonomic changes BP,respectively,in urethane-anesthetized mice (Tanida et al.,2007a) (Nagai et al.,1996b)and endocrine changes (Nagai et al.,1996a)due Furthermore,it was observed that bilateral electrolytic lesions of the to 2DG. SCN eliminated all changes in RSNA,GVNA and BP that were elicited Because of this background,the authors examined the effects of bi- by olfactory stimulation with either GFO or LVO scents in urethane- lateral electrolytic lesions of the SCN on the changes induced by anesthetized mice (Tanida et al.,2007a).After confirming these WAT-SNA&Lipolysis个 BAT-SNA BT Scent of 个 GFO ASNA BP 个 HI receptor RSNA BP 个 Oifactory Hypothalamic Hypothalamic GVNA Appetite epithelium TMN SCN H3 receptor WAT-SNA&Lipolysis↓ Scent of LVO BAT-SNA BT ASNA BP RSNA BP GVNA Appetite 个 Fig.2.Schematic figure summarizing the contents of the review.Scent stimulation of grapefruit oil(GFO)and lavender oil (LVO)are sensed by the olfactory epithelium,and the informa- tion of the olfactory epithelium send signals probably through limbic system to the hypothalamic tuberomammillary nucleus (TMN).Then,this signal is sent to the hypothalamic supra- chiasmatic nucleus(SCN).Finally,these information elicits changes in autonomic nerve activities(WAT-SNA.BAT-SNA.ASNA.RSNA and GVNA)and these changes caused alteration of physiological phenomena such as lipolysis,the body temperature(BT).blood pressure (BP)and appetite.RSNA and BP (Tanida et al., 2006), 3) intracranial administration of di￾phenhydramine eliminated the suppressing actions of either GFO or R-(+)-limonene on GVNA (Tanida et al., 2005b), and 4) intracranial in￾jection of thioperamide abolished the enhancing actions of either LVO or (±)-linalool on GVNA (Tanida et al., 2006). These findings suggest the following things: 1) the histamine H1 re￾ceptor is implicated in the mechanisms underlying the GFO-mediated increase in RSNA and BP, 2) the histamine H3 receptor is involved in the mechanisms underlying LVO-mediated decrease in RSNA and BP, 3) .the histamine H1 receptor in the mechanisms underlying the GFO-mediated decrease in GVNA, and 4) the histamine H3 receptor in the mechanisms underlying the LVO-mediated increase in GVNA. These findings suggest that olfactory stimulation with the GFO scent increases BP and decreases appetite through the histamine H1 receptor via the elevation in RSNA and the reduction in GVNA and other efferent vagal nerves innervating the gut, and that olfactory stimulation with the LVO scent lowers BP and increases appetite through the histamine H3 receptor via the suppression in RSNA and stimulation of GVNA and other efferent vagal nerves innervating the gut. 5. Roles of circadian clock mechanism in changes in autonomic neurotransmission and physiological phenomena due to GFO and LVO In mammals, the hypothalamic suprachiasmatic nucleus (SCN) func￾tions as a master circadian clock that forms circadian rhythms in phys￾iological phenomena and behaviors (Lowrey and Takahashi, 2004). The authors observed that the hyperglycemia induced by the intracranial administration of 2DG, an inhibitor of glucose utilization, is associated with the excitation of the sympathetic nerves innervating the pancreas, liver and adrenal glands, a reduction in the blood insulin level and ele￾vations in the blood glucagon and adrenaline levels in rats (Nagai et al., 1996a). Because a daily rhythm was observed in the hyperglyce￾mia induced by 2DG (Nagai et al., 1982), the effects of bilateral electro￾lytic lesions of the SCN on the 2DG-hyperglycemia were examined. Consequently, it was found that SCN lesions eliminated the hyperglyce￾mia (Yamamoto et al., 1984; Nagai et al., 1996a), autonomic changes (Nagai et al., 1996b) and endocrine changes (Nagai et al., 1996a) due to 2DG. Because of this background, the authors examined the effects of bi￾lateral electrolytic lesions of the SCN on the changes induced by olfactory stimulation with GFO and LVO scents. Consequently, the fol￾lowing results were observed: 1) bilateral lesions of the SCN abolished changes in the plasma glycerol concentration induced by olfactory stim￾ulation with either GFO or LVO scents in rats (Shen et al., 2007), 2) bilat￾eral lesions of the SCN eliminated the changes in RSNA, BP and GVNA elicited by olfactory stimulation with either GFO or LVO scents in rats (Tanida et al., 2005b, 2006), and 3) bilateral lesions of the SCN abolished the changes in BAT-SNA and BT caused by olfactory stimulation with ei￾ther GFO or LVO scents in rats (Tanida et al., 2008b). These findings suggest that the SCN is implicated in the changes in autonomic neurotransmission and physiological phenomena that were caused by olfactory stimulation with either GFO or LVO scents. The findings described above implicate the SCN in the changes in au￾tonomic neurotransmission and body functions induced by olfactory stimulation with GFO and LVO scents. However, when electrolytic le￾sions of the SCN are made, the neural fibers pass through the lesioned area are also cut, and this denervation might be responsible for the dis￾appearances of the autonomic and physiological responses to GFO and LVO. In consideration of this possibility, we tried to examine the changes in autonomic neurotransmission and physiological phenomena that were due to olfactory stimulation with GFO and LVO scents in mice lack￾ing the ability to form circadian rhythms due to genetic manipulation. We used gene-knockout (KO) mice including the chryptochrome 1 (Cry1) and chryptochrome 2 (Cry2) double KO mice and Clock-mutant mice, which have no electrolytic brain lesions. Before starting this study, the authors confirmed the changes in the autonomic neurotrans￾mission and BP induced by olfactory stimulation with GFO and LVO scents in intact control mice and obtained changes that were similar to those found in rats (Tanida et al., 2007a). That is, in urethane￾anesthetized mice, olfactory stimulation with the GFO scent enhanced the activities of the sympathetic nerves innervating the adrenal glands (ASNA), kidney (RSNA) and brown adipose tissue (BAT-SNA) and sup￾pressed GVNA, and olfactory stimulation with the LVO scent reduced ASNA, RSNA and BAT-SNA and increased GVNA (Tanida et al., 2007a). Olfactory stimulation with GFO and LVO scents increased and lowered BP, respectively, in urethane-anesthetized mice (Tanida et al., 2007a). Furthermore, it was observed that bilateral electrolytic lesions of the SCN eliminated all changes in RSNA, GVNA and BP that were elicited by olfactory stimulation with either GFO or LVO scents in urethane￾anesthetized mice (Tanida et al., 2007a). After confirming these Fig. 2. Schematic figure summarizing the contents of the review. Scent stimulation of grapefruit oil (GFO) and lavender oil (LVO) are sensed by the olfactory epithelium, and the informa￾tion of the olfactory epithelium send signals probably through limbic system to the hypothalamic tuberomammillary nucleus (TMN). Then, this signal is sent to the hypothalamic supra￾chiasmatic nucleus (SCN). Finally, these information elicits changes in autonomic nerve activities (WAT-SNA, BAT-SNA, ASNA, RSNA and GVNA) and these changes caused alteration of physiological phenomena such as lipolysis, the body temperature (BT), blood pressure (BP) and appetite. K. Nagai et al. / Autonomic Neuroscience: Basic and Clinical 185 (2014) 29–35 33