Table 4.

Animal models of the effect of thyroid hormones of sexual functioning

Study	N	Findings
Amadi et al29	40 (10 status post thyroidectomy alone, 10 status post thyroidectomy and repleated with thyroxine, 10 thryoxine treate alone, 10 contol)	Penile tissue from thyroidectomized rabbits had no response to PGE1 and decreased response to sildenafil. Thyroidectomized rabbits treated with thyroxine had normal response to PGE1 and decreased response to sildenafil. Rabbits who were treated with thyroxine but did not undergo thryoidectomy did not differ from control rabbits.
Yildirim et al.30	20 (10 status post thyroidectomy, 10 contol)	Relaxation of penile smooth muscle from hypothyroid rabbits was diminished when compared to controls (p<0.05). When adenosine, which increases NO release from endothelial cells, was added to the rabbit penile tissue, no difference in smooth muscle relaxation was observed (p>0.05).
Cihan et al.39	28 (7 thyroxine injected, 7 thyroxine injected + washout period, 7 saline injected, 7 with no injections)	Ejaculation model was based on seminal vesicle pressure and bulbospongiosus muscle contractility in response to para-chloramphetamine. Latency period between para-chloroamphetamine injection and ejaculation was significantly shorter in hyperthyroid group compared to other groups (202 vs 480, 465, 444 seconds, p<0.001 for all). The number of SV contractions, which studied the emission phase, was higher in hyperthyroid group than other 3 groups (p<0.05). In hyperthyroid rats, the number of SV contractions was inversely correlated with TSH (p=0.012, r=−0.94). However, all other emission phase parameters were the same in all 4 groups: baseline SV pressure, increase pressure from baseline after PCA, max amplitude of SV pressure in contractions (all p>0.05). The EMG activity area under the curve modeled expulsion and was greater in hyperthyroid group than other 3 groups (p<0.001). It also correlated with TSH values (p=0.016, r=−.094). Time separating first SV pressure increase (emission phase) and first organized BS EMG activity (expulsion phase) was not different between any of the groups (p>0.05
Shifren et al.40	31,581	A positive correlation between all domains of sexual dysfunction and a history of thyroid disorder was observed: desire (OR=1.18, p<0.05), orgasm (OR=1.22, p<0.05), and arousal (OR=1.19, p<0.05)