Testosterone affects the allocation of reproductive effort in male birds. Elevated testosterone causes male dark-eyed juncos, Junco hyemalis, to decrease care of dependant offspring, but this generalization is based largely on reduced provisioning rates by males treated with testosterone. Therefore, we used a predator model to explore the relationship between testosterone and nest defence, a mo...

Hormonally induced azoospermia induced by weekly im injections of testosterone enanthate provides effective and reversible male contraception, but more practical regimens are needed. Given our previous findings that six 200-mg pellets implanted subdermally produced more stable, physiological T levels and reduced the delivered T dose by more than 50% while maintaining equally effective suppressi...

introduction: boron possesses widespread properties and is important for human and animal nutrition. since boron is rapidly bioavailable, the objective of the present study was to determine whether acute (hourly or daily), and weekly supplementationcould have any significant biological effects on the synthesis of steroids as well as inflammatory biomarkers. methods: eight male volunteers partic...

Steroid hormones induce rapid membrane receptor-mediated effects that appear to be separate from long-term genomic events. The membrane receptor-mediated effects of androgens on GT1-7 GnRH-secreting neurons were examined. We observed androgen binding activity with a cell-impermeable BSA-conjugated testosterone [testosterone 3-(O-carboxymethyl)oxime (T-3-BSA)] and were able to detect a 110-kDa p...

The impact of exogenic testosterone (T): 1.5 and 3.0 mg/kg.bw) and 19-nortestosterone 17-decanoate (ND): 1.5 and 7.5 mg/kg.bw) in castrated male rats was evaluated based on: (a) weight increase of the androgen target tissues, respecting the Hershberger methodology; (b) the 17α and β-testosterone, 17 α and β-estradiol and 17 α and β-nortestosterone levels using the GC-MS/MS technique; and (c) ob...

The present study examined the effects of the androgen steroid, dihydrotestosterone (DHT), on murine T-cell production of a number of lymphokines. Direct exposure of murine T cells to DHT in vitro was found to reduce the amount of interleukin-4 (IL-4). IL-5, and y-interferon (ylFN) produced after activation with anti-CD3 without affecting the production of IL-2. Exposure of T cells to either an...

BACKGROUND To examine the effect of serum testosterone levels on survival in a consecutive series of men with confirmed coronary disease and calculate the prevalence of testosterone deficiency. DESIGN Longitudinal follow-up study. SETTING Tertiary referral cardiothoracic centre. Patients 930 consecutive men with coronary disease referred for diagnostic angiography recruited between June 200...

Hormones have been suggested as a key proximate mechanism that organize and maintain consistent individual differences in behavioural traits such as aggression. The steroid hormone testosterone in particular has an important activational role in mediating short-term aggressive responses to social and environmental stimuli within many vertebrate systems. We conducted two complementary experiment...

AIMS/INTRODUCTION The present study was designed to investigate the correlations between the serum testosterone level and insulin sensitivity in elderly male type 2 diabetes patients with osteoporosis. MATERIALS AND METHODS A total of 35 elderly male patients with type 2 diabetes (type 2 diabetes group), 30 elderly male type 2 diabetes patients combined with osteoporosis (DO group) and 30 hea...

We previously showed that testosterone, administered in vivo, increases the tone of cerebral arteries. A possible underlying mechanism is increased vasoconstriction through the thromboxane A2 (TxA2) pathway. Therefore, we investigated the effect of chronic testosterone treatment (4 wk) on TxA2 synthase levels and the contribution of TxA2 to vascular tone in rat middle cerebral arteries (MCAs). ...