ABSTRACT
The possible role of thyroid hormones in the Nitric Oxide (NO)-mediated response to sexual stimulation, and on prostaglandin E1 (PGE1) and Sildenafil in the treatment of erectile dysfunction was investigated using the corpus cavernosum of the New Zealand rabbit animal model. The parameters studied were penile erection monitored as contractile force of the erectile tissue, sperm count and motility; in parallel with the haematocrit, red cell count or rheology, Heart Rate (HR), Mean Arterial Pressure (MAP), Thyroid Stimulating Hormones (TSH) and Thyroxine levels. Hypothyroidism or thyroidectomy was found to cause depletion of Endothelium Derived Relaxant Factor (EDRF) thereby causing very feeble contraction of the cavernosum muscle, in both prostaglandin E1 (PGE1) and sildenafil, oligospermia and less than 45 % motile sperms. Thyroxine treatment produced contraction proportionate to the concentrations of PGE1 and Sildenafil; providing evidence that the erectogenic actions of both PGE1 and Sildenafil are possible only in the presence of adequate thyroid hormone level.
Subject(s)
Penile Erection/drug effects , Thyroid Hormones/pharmacology , Alprostadil/pharmacology , Animals , Blood Pressure/drug effects , Erythrocyte Count , Heart Rate/drug effects , Hematocrit , Male , Muscle Contraction/drug effects , Muscle, Smooth/drug effects , Penile Erection/physiology , Piperazines/pharmacology , Purines/pharmacology , Rabbits , Sildenafil Citrate , Sperm Count , Sperm Motility/drug effects , Sulfones/pharmacology , Thyroid Hormones/blood , Thyroid Hormones/physiology , Thyroidectomy , Thyrotropin/blood , Thyrotropin/pharmacology , Thyrotropin/physiology , Thyroxine/blood , Thyroxine/pharmacology , Thyroxine/physiology , Vasodilator Agents/pharmacology , omega-N-Methylarginine/pharmacologyABSTRACT
Recently, the thyroid hormone has been shown to cause increase in Ca2+ concentration by mobilizing intracellular Ca2+. The mobilization of intracellular Ca2+ in the absence of transmembrane Ca2+ influx has been accepted as evidence for a cell-surface Ca2+- receptor. The possible role of thyroid hormone in the regulation of cellular functions by Ca2+-channel was investigated using parameters proven to indispensably involve Ca2+: Bleeding and clotting times and rat uterine muscle activity in Ca2+-free Tyrode's solution. Adult female Wistar rats divided into four groups, namely; (i) Control, (ii) Thyroidectomized, (iii) Throidectomized-treated with thyroxine and (iv) Thyroxine-treated; were fed on rat chow. While groups i and ii were allowed access to tap water ad libitum for 60 days, groups iii and iv received tyroxine (10mg/kg body weight) every alternate day and tap water ad libitum for 60 days. All groups were kept in an air-conditioned room till they were euthanized. The results showed that thyroxine elicited biphasic contraction in Ca2+ - depletion and potentiated uterine contraction during Ca2+- loading (P<0.001). Inhibition of contractions in thyroidectomy, showed dependency of Ca2+ on thyroid hormones for the regulation of cellular functions.
Subject(s)
Calcium/metabolism , Muscle Contraction/drug effects , Muscle, Smooth/drug effects , Thyroxine/pharmacology , Administration, Oral , Animals , Bleeding Time , Calcium/blood , Female , Injections, Intravenous , Muscle, Smooth/metabolism , Muscle, Smooth/physiology , Rats , Rats, Wistar , Thyroidectomy , Thyroxine/administration & dosage , Thyroxine/blood , Uterus/drug effects , Uterus/physiology , Whole Blood Coagulation TimeABSTRACT
Recently, the thyroid hormone has been shown to cause increase in calcium ion (Ca(2+)) concentration by mobilizing intracellular calcium((2+)). The mobilization of intracellular calcium((2+)) in the absence of transmembrane calcium((2+)) influx has been accepted as evidence for a cell-surface Ca((2+))-receptor. The possible role of thyroid hormone in the regulation of cellular functions by ca((2+)-channel was investigated using parameters proven to indispensably involve Ca(2+). Bleeding and clotting times and rat uterine muscle activity in Ca(2+)-free Tyrode's solution. Adult female Wistar rats divided into four groups, namely; (i) Control, (ii) Thyroidectomized, (iii) Throidectomized-treated with thyroxine and (iv) Thyroxine-treated; were fed on rat chow. While groups i and ii were allowed access to tap water ad libitum for 60 days, groups iii and iv received tyroxine (10 mg/kg body weight) every alternate day and tap water ad libitum for 60 days. All groups were kept in an air-conditioned room till they were euthanized. The results showed that thyroxine elicited biphasic contraction in Ca (2+)-depletion and potentiated uterine contraction during Ca(2+)-loading (P < 0.001). Inhibition of contractions in thyroidectomy, showed dependency of Ca (2+) on thyroid hormones for the regulation of cellular functions.
