Olfactory bulbectomy and raphe nucleus relationship: a new vision for well-known depression model

Abstract

Background/aim: The olfactory bulbectomy (OBX) technic is a well-known animal model for depression. According to serotonin hypothesis of depression, one of the possible explanations to this mechanism is the destroying effect of OBX on raphe nuclei which especially include serotonergic neurons. In this study, we aimed to explore histopathological findings in raphe nuclei in OBX rats.

Materials and methods: Forty-eight rats (8 control group, 10 sham group, and 30 as the study group) were used. No procedure was applied to the control group. Only frontal burr holes were performed at the level of olfactory bulbs (OBs) on the sham group. Mechanical OBX by compression was applied to 20 rats and the OBs of 10 rats were cauterized. Their OBs, olfactory cortices, raphe nuclei were extracted, tissue specimens were taken than examined by using histopathological methods including hematoxylin and eosin, S-100, and TUNEL staining. Physical dissector method was used to evaluate the number of living and apoptotic neurons in the raphe nuclei.

Results: Prominent neuronal loss and morphological changes in the dorsal raphe nuclei were detected in study groups.

Conclusion: Raphe nuclei degeneration, related alterations in neurotransmitter system activities and functional brain connectivity might be related to neurobiology of depression.

Keywords:

• Depression
• olfactory bulbectomy
• raphe nuclei
• neurodegeneration
• rat

Disclosure statement

The authors have no conflicts of interest to declare.

Additional information

Notes on contributors

Halil Ozcan

Halil Ozcan was born in Elazig/Turkey in 1980. Graduated from Istanbul University Medical Faculty in 2004. He practised Psychiatry Residency İn Hacettepe University Medical Faculty. He is married with 3 kids, interested in Biological Psychiatry and eclectic psychotherapy.

Nazan Aydın

Nazan Aydin was born in Erzurum. Graduated from Ataturk University Medical Faculty and practised Psychiatry Residency Program at the same hospital. Married with 2 daughters, interested in Biological Psychiatry and also an experinced applier of Interpersonal Psychotherapy.

Mehmet Dumlu Aydın

Mehmet Dumlu Aydin is professor of neurosurgery in Ataturk University. Interested in Behavioral Neurology and Brain Tumors. He has more than 100 papers especially in the field of behavioral neuroscience , has a booklet about olfactory system and behavior relation.

Elif Oral

Elif Oral is a psychiatry specialist and professor in Izmir/Turkey. She worked in Ataturk University Psychiatry Department for 12 years. Married with 3 kids, interested in sleep biology and women mental health.

Cemal Gündoğdu

Cemal Gundogdu is a professor of pathology, worked in Ataturk University for more than 30 years, interested in general pathology and bone marrow biology, he was retired and works in private practice.

Sare Şipal

Sare Sipal is professor of pathology in Ataturk University Medical School, interested in neuropathology and gynecological pathology.

Zekai Halıcı

Zekai Halici is professor of medical pharmacology in Ataturk University, he is an experienced researcher on animal researches has more than 150 paper in qualified journals works in different fields of pharmacology, he owns patents.