Related Experiment Video

Updated: May 20, 2026

Measuring Sperm Guidance and Motility within the Caenorhabditis elegans Hermaphrodite Reproductive Tract
10:07

Measuring Sperm Guidance and Motility within the Caenorhabditis elegans Hermaphrodite Reproductive Tract

Published on: June 6, 2019

Autocrine regulation of human sperm motility by the met-enkephalin opioid peptide

Nerea Subirán1, Luz Candenas, Francisco M Pinto

  • 1Department of Physiology, Faculty of Medicine and Dentistry, University of the Basque Country, Leioa, Bizkaia. nerea.subiran@ehu

Fertility and Sterility
|July 4, 2012
PubMed
Abstract

Insights

Met-enkephalin and its precursor PENK are present in human sperm, influencing motility. This opioid system regulation offers new insights into male fertility and potential male contraception targets.

Area of Science:

  • Reproductive Biology
  • Molecular Endocrinology
  • Sperm Physiology

Background:

  • The role of endogenous peptides in sperm function is not fully understood.
  • Opioid peptides, like enkephalins, are known to have diverse physiological roles.

Purpose of the Study:

  • To investigate the presence of met-enkephalin and its precursor pro-enkephalin (PENK) in human spermatozoa.
  • To determine the impact of endogenous and exogenous enkephalins on sperm motility.

Main Methods:

  • Expression analysis using RT-PCR, Western blot, and immunofluorescence.
  • Sperm motility assessment after incubation with enzyme inhibitors and naloxone.
  • Met-enkephalin secretion analysis via flow cytometry.

Main Results:

  • Met-enkephalin and PENK were detected in the head of human sperm cells.
  • Endogenous met-enkephalin enhanced sperm motility.
  • Exogenous met-enkephalin exhibited a biphasic effect on motility, suggesting receptor subtype involvement.

Conclusions:

  • Met-enkephalin acts as an endogenous mediator of human sperm motility.
  • This autocrine regulation by the opioid system impacts male factor fertility.
  • The findings suggest potential targets for male contraception development.

More Related Videos

Two Types of Assays for Detecting Frog Sperm Chemoattraction10:02

Two Types of Assays for Detecting Frog Sperm Chemoattraction

Published on: December 27, 2011

Phosphopeptide Analysis of Rodent Epididymal Spermatozoa09:30

Phosphopeptide Analysis of Rodent Epididymal Spermatozoa

Published on: December 30, 2014

Related Concept Videos

Male Sexual Response: Erection & Ejaculation01:17

Male Sexual Response: Erection & Ejaculation

Sexual stimulation can take various forms, such as physical touch and visual or auditory cues. When this happens, the parasympathetic reflex in the sacral portion of the spinal cord is activated. This reflex stimulates the release of nitric oxide (NO), which then dilates the arterioles in the penis, increasing blood flow to the erectile tissues - the corpora cavernosa and corpus spongiosum.
The blood filling the erectile tissues compresses the veins, which helps to prevent blood from leaving...
Sperm Transport01:15

Sperm Transport

The journey of sperm from its origin to the point of ejaculation begins within the seminiferous tubules of the testis. Here, Sertoli cells produce fluid that propels non-motile sperm through a series of conduits, starting with the straight tubules leading to the rete testis. This interconnected network of tubules acts as the initial pathway for sperm, guiding them into the efferent ductules and then into the epididymis for maturation.
The maturation phase occurs in the epididymis, where sperm...
Opioid Receptors: Overview01:22

Opioid Receptors: Overview

Opioid receptors, including the mu (μ, MOR), delta (δ, DOR), and kappa (κ, KOR) types, belong to the rhodopsin family of G protein-coupled receptors. These receptors are located throughout the central and peripheral nervous systems and in non-neuronal tissues such as macrophages and astrocytes. Opioid receptor ligands can be categorized into agonists or antagonists. Highly selective agonists include [d-Ala2, MePhe4, Gly(ol)5]-enkephalin or DAMGO for MOR, [D-Pen2, D-Pen5]-enkephalin or DPDPE for...
Hormonal Regulation of the Menstrual Cycle01:22

Hormonal Regulation of the Menstrual Cycle

The ovarian cycle regulates endometrial changes throughout a single menstrual cycle via the coordinated action of gonadotrophin-releasing hormone (GnRH) and gonadotrophins.
At puberty, GnRH begins a pulsatile release pattern, which triggers the anterior pituitary gland to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The frequency and amplitude of GnRH pulses vary across the menstrual cycle, with faster pulses favoring LH release and slower pulses favoring FSH release.
Feedback Regulation of Calcium Concentration01:27

Feedback Regulation of Calcium Concentration

Calcium is an essential signaling molecule required for various cellular functions. Calcium pumps and ion channels on cell and organellar membranes, such as those on the endoplasmic reticulum (ER), regulate calcium concentrations inside the cell. They remain closed, keeping the cytosolic calcium levels low at a resting state.
Various transmembrane receptors, such as G protein-coupled receptors (GPCRs), elicit a response to extracellular signals by increasing cytosolic calcium. Activated GPCRs...
Regulation of Food Intake01:30

Regulation of Food Intake

Short-term regulation of food intake primarily involves neural signals from the gastrointestinal (GI) tract, blood nutrient levels, and GI tract hormones. Communication between the gut and brain via vagal nerve fibers plays a significant role in evaluating the contents of the gut. Clinical studies have shown that protein ingestion produces a more prolonged response in these nerve fibers compared to an equivalent amount of glucose. Additionally, the activation of stretch receptors caused by GI...