Protocol for reversible induction of hyposmia in rats using intranasal gadolinium chloride administration

Here, we present a protocol for intranasal administration of gadolinium chloride in adult rats to induce transient olfactory dysfunction. We describe steps for preparing gadolinium chloride solution, bilateral intranasal infusion under isoflurane anesthesia, and post-infusion stabilization. We then detail procedures for animal monitoring and behavioral assessment using the hidden cookie test. The procedure produces reproducible impairment in olfactory-guided food-seeking behavior, detectable the day after administration and lasting 7 days. Behavioral performance then returns to baseline, indicating recovery of olfactory-guided function.