Biomaterial Database

Median raphe injections of 8-OH-DPAT lower frequency thresholds for lateral hypothalamic self-stimulation. 1995

P J Fletcher, and M Tampakeras, and J S Yeomans

Section of Biopsychology, Clarke Institute of Psychiatry, Toronto, Ontario, Canada.

The selective 5-HT1A agonist 8-hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) reduces the activity of brain 5-HT neurons via somatodendritic autoreceptors located in the midbrain raphe nuclei. This action of 8-OH-DPAT results in reduced 5-HT synthesis and release of 5-HT in terminal regions. Previous studies have shown that injecting 8-OH-DPAT into the raphe nuclei stimulates feeding, sexual behaviour, and locomotor activity, and serves as an unconditioned stimulus for inducing a conditioned place preference. This behavioural profile suggests that raphe injections of 8-OH-DPAT facilitate reward-related behaviour. The present study tested this hypothesis by investigating the effects of median raphe injections of 8-OH-DPAT on sensitivity to lateral hypothalamic (LH) self-stimulation. Frequencies required to sustain half-maximal rates of responding were determined following injection of saline or various doses of 8-OH-DPAT (0.2-5 micrograms) into the median raphe. In four rats with accurate injection sites 8-OH-DPAT dose-dependently lowered frequency thresholds by up to 40%. In the remaining rats injection sites were located outside the median raphe, and 8-OH-DPAT either slightly raised or failed to lower frequency thresholds. These results show that 8-OH-DPAT injected into the median raphe facilitates brain stimulation reward, and suggest that acute reductions in 5-HT neurotransmission may enhance sensitivity to rewarding stimuli. The possible interactions between 5-HT neurons and efferent systems utilizing dopamine and acetylcholine as neurotransmitters in mediating this effect are discussed.

UI	MeSH Term	Description	Entries
D007026	Hypothalamic Area, Lateral	Area in the hypothalamus bounded medially by the mammillothalamic tract and the anterior column of the FORNIX (BRAIN). The medial edge of the INTERNAL CAPSULE and the subthalamic region form its lateral boundary. It contains the lateral hypothalamic nucleus, tuberomammillary nucleus, lateral tuberal nuclei, and fibers of the MEDIAL FOREBRAIN BUNDLE.	Lateral Hypothalamic Area,Lateral Hypothalamic Nucleus,Tuberomammillary Nucleus,Accessory Nucleus of the Ventral Horn,Area Hypothalamica Lateralis,Area Lateralis Hypothalami,Lateral Hypothalamus,Lateral Tuberal Nuclei,Lateral Tuberal Nucleus,Area Hypothalamica Laterali,Area Lateralis Hypothalamus,Area, Lateral Hypothalamic,Areas, Lateral Hypothalamic,Hypothalami, Area Lateralis,Hypothalamic Areas, Lateral,Hypothalamic Nucleus, Lateral,Hypothalamica Laterali, Area,Hypothalamica Lateralis, Area,Hypothalamus, Area Lateralis,Hypothalamus, Lateral,Lateral Hypothalamic Areas,Laterali, Area Hypothalamica,Lateralis Hypothalami, Area,Lateralis Hypothalamus, Area,Lateralis, Area Hypothalamica,Nuclei, Lateral Tuberal,Nucleus, Lateral Hypothalamic,Nucleus, Lateral Tuberal,Nucleus, Tuberomammillary,Tuberal Nuclei, Lateral,Tuberal Nucleus, Lateral
D007267	Injections	Introduction of substances into the body using a needle and syringe.	Injectables,Injectable,Injection
D008297	Male		Males
D011903	Raphe Nuclei	Collections of small neurons centrally scattered among many fibers from the level of the TROCHLEAR NUCLEUS in the midbrain to the hypoglossal area in the MEDULLA OBLONGATA.	Caudal Linear Nucleus of the Raphe,Interfascicular Nucleus,Nucleus Incertus,Rostral Linear Nucleus of Raphe,Rostral Linear Nucleus of the Raphe,Superior Central Nucleus,Central Nucleus, Superior,Incertus, Nucleus,Nuclei, Raphe,Nucleus, Interfascicular,Nucleus, Raphe,Nucleus, Superior Central,Raphe Nucleus
D003216	Conditioning, Operant	Learning situations in which the sequence responses of the subject are instrumental in producing reinforcement. When the correct response occurs, which involves the selection from among a repertoire of responses, the subject is immediately reinforced.	Instrumental Learning,Learning, Instrumental,Operant Conditioning,Conditionings, Operant,Instrumental Learnings,Learnings, Instrumental,Operant Conditionings
D004305	Dose-Response Relationship, Drug	The relationship between the dose of an administered drug and the response of the organism to the drug.	Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012201	Reward	An object or a situation that can serve to reinforce a response, to satisfy a motive, or to afford pleasure.	Rewards
D012653	Self Stimulation	The act or process of inducing or increasing the level of arousal in oneself. It can be observed in various situations; for example, infants who are understimulated may explore their surroundings or babble to themselves.(https://dictionary.apa.org/self-stimulation accessed 12/30/2020)	ICSS Intracranial Self-Stimulation,Intracranial Self Stimulation,Self-Stimulation,Intracranial Self Stimulations,Self Stimulation, Intracranial,Self Stimulations,Self Stimulations, Intracranial,Self-Stimulations,Stimulation, Self,Stimulations, Self
D017208	Rats, Wistar	A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.	Wistar Rat,Rat, Wistar,Wistar Rats