Hirotaka Matsushita

Administration of antisense DNA for ghrelin causes an antidepressant and anxiolytic response in rats

RATIONALE Ghrelin is a peptide of 28 amino acids found in mammals that increases the release of growth hormone, food intake, and body weight. OBJECTIVES We investigated the relationship between ghrelin and the states of anxiety and depression by giving rats either antisense DNA for ghrelin, scrambled DNA or vehicle into the lateral ventricle of rats. RESULTS In forced swimming tests, rats that received antisense DNA decreased the length of time that they were immobile in the water. Ghrelin antisense oligonucleotides produced an anxiolytic-like effects in the elevated plus maze test, black and white test, or conditioned fear tests. Treatment with antisense DNA for ghrelin significantly decreased rat body weight. No significant effect on general locomotor activity was seen. CONCLUSIONS These results suggest that administration of antisense DNA for ghrelin causes an antidepressant and anxiolytic response in rats.

Ghrelin gene polymorphism is associated with depression, but not panic disorder.

Ghrelin, which was identified for the first time by Kojima et al. in rat stomach, is a novel peptide of 28 amino acids, which acts as endogenous ligand for the growth hormone secretagogue receptor (Kojima et al., 1999; Kojima and Kangawa, 2005). Thus, one function of ghrelin is to increase pituitary release of growth hormone (Arvat et al., 2000). Regional distribution of ghrelin receptors suggests that the peptide could be related to emotional processes. Some researchers reported that both central (e.g. intraventricular) and peripheral (e.g. intraperitoneal) administration of ghrelin is a potent inducer of anxiogenic behavior in mice (Asakawa et al., 2001; Carlini et al., 2002). Similar research indicates that ghrelin induces anxiogenesis in rats. Recently, we reported that administration of antisense DNA for ghrelin causes an antidepressant and anxiolytic response in rats (Kanehisa et al., 2006).

Anticipatory anxiety-induced changes in human lateral prefrontal cortex activity.

It has been suggested that frontal brain asymmetry is associated with differences in basic emotional dimensions, particularly in activation of systems underlying avoidance-withdrawal behavior. We examined regional cerebral oxygenated hemoglobin (O2Hb) levels in human medial prefrontal cortex (MPFC) using near-infrared reflection spectroscopy (NIRS) prior to and during anticipatory anxiety to determine if NIRS could detect any anxiety-related changes. Transient anxiety was induced in 56 normal volunteers by anticipation and a painful shock to the right-hands median nerve. Pre- and post-anxiety affective statuses were measured using the State-Trait Anxiety Inventory (STAI) and Temperature Character Inventory (TCI). NIRS recorded from the left and right frontal brain regions. Right MPFC O2Hb was significantly increased relative to left MPFC O2Hb during anticipation of the shock. Right-sided O2Hb increases were significantly correlated with the TCI Harm Avoidance subscale. These results support the hypothesis that O2Hb levels in the right frontal region correlate with anxiety or heightened negative affect.

Reduced anxious behavior in mice lacking the CCK2 receptor gene

Cholecystokinin 2 (CCK2) receptors have been implicated as mediators of anxiety in standard mouse models such as exploratory behavior both in black and white test boxes and in elevated plus-mazes. We investigated the role of the CCK2 receptor in anxiety by evaluating the behavior of mice lacking the gene for this receptor in these standard anxiety models (i.e., exploratory behavior in a black and white test box and exploratory behavior in an elevated plus-maze). In the black and white test box, mice lacking the CCK2 receptor gene showed significantly increased numbers of transitions between the boxes compared to control mice. In the elevated plus-maze, mice lacking the CCK2 receptor gene displayed significantly more head dips than control mice. These results suggest that mice lacking the CCK2 receptor gene are less anxious than normal mice.

Spatial memory impairment in OLETF rats without cholecystokinin - a receptor.

Cholecystokinin (CCK) is one of the most abundant neurotransmitter peptides in the brain. As Otsuka Long-Evans Tokushima Fatty (OLETF) rats lack CCK-A receptor because of a genetic abnormality, we examined whether learning and memory were impaired in these animals using both Morris water maze (MWM) and step-through type passive avoidance (PA) learning test. In the MWM test, memory impairment was observed in OLETF rats. The number of errors was also significantly higher, and that of the correct choices was significantly lower in OLETF rats compared to the controls [Long-Evans Tokushima Otsuka (LETO)] rats. In PA, OLETF rats did not show facilitating response 24 h after training. From these observations, we concluded that a spatial memory was impaired in the OLETF rats.

Anxiolytic suppression of repetitive transcranial magnetic stimulation-induced anxiety in the rats

Repetitive transcranial magnetic stimulation (rTMS) is effective for treatment of several psychiatric disorders such as depression and anxiety disorder. However, some reports suggest that rTMS induced anxiety in normal volunteers. Consistent with this observation, we have reported that chronic rTMS induces anxiety in normal rats which was suppressed by chronic treatment, but not acute paroxetine treatment. The current study evaluates rTMS as animal model of anxiety by investigating the effect of rTMS on anxiety behaviors and the ability of standard anxiolytics to block expression of these behaviors. We found that 10-day rTMS induced anxiety in normal rats, as evidenced by expression of anxiety behaviors in the elevated plus-maze. This anxiety was suppressed by acute treatment with diazepam, alprazolam, or buspirone suggesting that chronic rTMS treatment provides a good animal model for anxiety.

A young woman with visual hallucinations, delusions of persecution and a history of performing arson with possible three‐generation Fahr disease

Objective:  Fahr disease (FD) is a rare neurological and psychiatric disorder. The disease is classified by intracranial calcification of the basal ganglia with the globus pallidus region being particularly affected. We examined a young woman with visual hallucinations, delusions of persecution and a history of performing arson with possible third‐generation FD.

Anxiolytic Effect of Hepatocyte Growth Factor Infused into Rat Brain

Background: Hepatocyte growth factor (HGF) has the capacity to selectively direct thalamocortical projections into an intermediate target, the pallidum, and eventually to their final cortical destination. HGF may have a role in the mediation of anxiety. Very little is known about other central behavioral effects of HGF. Objective: Our aim was to determine what effect HGF has on anxiety in rats. Methods: HGF was infused at a constant rate into cerebral lateral ventricles and its effect on anxiety in rats was monitored. Results: In the elevated plus maze test and the black and white box test, HGF administration caused all indicators of anxiety to increase. No significant effect on general locomotor activity was seen. Conclusion: HGF infusion into the brain produces an anxiolytic effect.

Association between the obestatin and BDNF gene polymorphism and panic disorder, and depressive disorder.

Panic disorder (PD) is an anxiety disorder characterized by unexpected and repeated episodes of intense fear accompanied by physical symptoms including difficulty breathing. Obestatin, hormone derived from the preproghrelin gene, affects memory performance and causes anxiolytic effects in rats (Carlini et al., 2007). In this study, we examined the association of an obestatin polymorphism (Gln90Leu) with major depressive disorder (MDD) and PD. We also examined the association of the BDNF Val66Met variant, the obestatin Gln90Leu with MDD and PD (Hong et al., 2003; Lam et al., 2004; Shimizu et al., 2005). The participants in this study consisted of 138 patients diagnosed with PD and 275 patients with MDD from Oita University Faculty of Medicine. Control participants were 242. Written informed consent was obtained from all of the participants before the donation of their blood samples. The diagnoses were based on Diagnostic and Statistical Manual of Mental Disorders, fourth edition (American Psychiatric Association). This study was approved by the ethics community of Oita University Faculty of Medicine. Genomic DNA was extracted from the leukocytes with a DNA Extraction Kit (Wako Pure Chemical Industries, Osaka, Japan). The obestatin gene was genotyped by amplifying the region encoding the Gln15Leu locus using primers 50-AACCTGGCTGAGGTGTCACT-30 and 50-ctggctgtgctgcaggta-30, which was followed by digestion with A1wNI. PCR conditions are available by request. In the BDNF gene, the region that encodes Val66Met was genotyped using the primers 50-actctggagagcgtgaatgg30 and 50-actactgagcatcaccctgga-30, followed by digestion with Eco72I. All restriction enzyme digests were separated on 3% agarose gels. The w test-based Hardy– Weinberg equilibrium program was used to perform the Hardy–Weinberg equilibrium test for all single nucleotide polymorphisms in this study. We used Fisher’s exact test for the PD group versus control group. The genotypic frequencies of BDNF G196A were 30.5% (G/G), 40.2% (G/A), and 29.3% (A/A) in PD patients (P = 0.011); 32.8% (G/G), 53.7% (G/A), and 13.5% (A/A) in MDD patients (P = 0.082); and 23.0% (G/G), 59.8% (G/A), and 17.2% (A/A) in the controls. The allelic frequencies were 50.6% (G) and 49.4% (A) in PD patients (P = 0.63), 59.6% (G) and 40.4% (A) in MDD patients (P = 0.052), and 52.9% (G) and 47.1% (A) in the controls. We also investigated the association between the presence of an obestatin gene polymorphism and PD and depression. Mutant frequencies were 1% in PD patients, 9.2% in MDD patients, and 5% in the controls. There was no significant difference in single nucleotide polymorphism distribution between the healthy controls and the PD and MDD patients. This investigation of an association between polymorphisms in two genes produced two major findings. First, the Val66Met mutation in BDNF is associated with PD, a finding that is not consistent with reports by Lam et al. (2004). One possible explanation for the discrepancy could be the different methodologies that were employed in the studies. Second, the Gln90Leu obestatin variant has no association with PD and MDD. This finding suggests that this polymorphism does not contribute to genetic susceptibility to PD and MDD. Further studies are needed to determine the role played by obestatin in the etiology of depressive disorder. These results suggest that BDNF polymorphism is connected to PD.

Administration of antisense DNA for hepatocyte growth factor causes an depressive and anxiogenic response in rats

Hepatocyte growth factor (HGF) is induced in neurons during ischemia and is neuroprotective against post-ischemic delayed neuronal death in the hippocampus. HGF might play an important role in the maturation and functioning of these neurons in the hippocampus. Our aim was to determine what effect HGF antisense has on depression and anxiety in rats. HGF antisense was infused at a constant rate into cerebral lateral ventricles and its effect on anxiety in rats was monitored. In forced swimming test, rats that received antisense DNA increased the length of time that they were immobile in the water. In the elevated plus maze test, the black and white box test and conditioned fear test, HGF antisense administration caused all indicators of anxiety to increase. Number of HGF-positive cells in C1 of hippocampus was significantly decreased in the HGF antisense-infused group compared to the vehicle- and scrambled oligonucleotide-treated group. No significant effect on general locomotor activity was seen. These results indicate that inhibition of HGF induces an increase in depression and anxiety-related behaviors suggesting a depressive and anxiogenic-like effect.