Scratching Behavior

DERMATOLOGY

Dermatological diseases represent a major health problem due to the substantial patient population that is affected. Psoriasis, Allergic Contact Dermatitis (ACD) and Atopical Dermatitis (Allergic or Irritant Contact Dermatitis) are the major skin diseases of immunological origin.

Scratching Behavior

Itch is a sensation that provokes a desire to scratch. Itch accompanies various skin diseases such as atopic dermatitis and urticaria.
Mouse models are widely used for understanding molecular and neuronal mechanisms of itch circuit, because this reflex can be easily observed and quantified in this species.

Evaluation of the inhibitory effects of drugs on various pruritogen-induced scratching behaviors in mice.

- Promethazine (H1 Histamine receptor antagonist) and of U-50488H (K-opioid agonist) to antagonize itching behavior induced by an intradermal injection of histamine in the mouse.

- Promethazine (H1 Histamine receptor antagonist), U-50488H (K-opioid agonist) and of HC-030031 (selective TRPA1 channel blocker) to antagonize itching behavior induced by an intradermal injection chloroquine in the mouse.

> Histamine (200 µg/mouse i.d.) induced a clear itching behavior. →

> Both Promethazine (5 mg/kg i.p.) and U-50488H (10 mg/kg i.p.) significantly reduced histamine-induced itching.    ↓

Itching behavior induced by histamine, chloroquine and serotonine in the rat

> Serotonine (50 µg/rat i.d.) induced a clear itching behavior in the rat, while neither histamine (200 µg/rat) nor chloroquine (100 µg/rat i.d.) showed clear effects.     →

> Serotonin-induced scratching behavior in the rat was only moderately reduced by naltrexone given i.p. at 5 mg/kg, while it was markedly reduced when naltrexone was given s.c. at 1 mg/kg. ↓